MULTIPLE ANTIBIOTIC RESISTANCE OPERON ASSAYS

Abstract: An isolated and cloned region of a bacterial chromosome containing a multiple antibiotic resistance operon is disclosed. A description of the structure and function of the operon is provided as are assorted recombinant DNA constructs involving the operon or portions thereof. The diagnostic, therapeutic and experimental uses of these constructs are also disclosed. Methods of evaluating the antibiotic effectiveness of compositions are disclosed and methods of treatment employing effective compositions are provided.

Description: MULTIPLE ANTIBIOTIC RESISTANCE OPERON ASSAYS FIELD OF THE INVENTION This invention relates generally to the field of antimicrobial therapy. In particular, the present invention relates to methods and products useful in inhibiting the growth of bacteria or other microbes. In addition, this invention relates to identifying loci in bacteria or other microbes which affect antibiotic or antimicrobial susceptibility and to the production of bacterial strains useful in the field of antimicrobial therapy. BACKGROUND OF THE INVENTION Antibiotic or antimicrobial substances have long been used to inhibit the growth of bacteria or other microbes and to treat bacterial or microbial infections in humans, other animals, and in tissue culture. The use of antibiotics or antimicrobials in a treatment regimen, however, has the undeεireable effect of selecting for bacteria or other microbes which are resistant to those antibiotics or antimicrobials administered or applied. As a result, treatment regimens can be adversely affected or, in some cases, rendered ineffective. This necessitates a continual search for new antibiotics and antimicrobials. Of particular interest is the discovery of bacteria which express a multiple antibiotic resistance phenotype (Mar) . This phenotype entails simultaneous resistance to a multiplicity of antibiotics which are unrelated in chemical structure, ,'he appearance cf such bacteria and infections by such bacteria greatly increase the difficulty of identifying effective a-tibictics and treating infections in humans or other animals. Multiple antibiotic resistance in bacteria is most commonly associated with the presence of plasmids which contain one or more resistance genes, each encoding a single antibiotic resistance phenotype (Clewell 1981; Foster 1983). Multiple antibiotic resistance associated with the chromosome, however, has also been reported in Klebsiella, Enterobacter, Serratia (Gutmann et al. 1985), Neisseria (Johnson and Morse 1988), and Escherichia (George and Levy 1983a) . Bacteria expressing the multiple antibiotic resistance phenotype can be isolated by selecting bacteria with a single antibiotic and then screening for cross-resistance to structurally unrelated antibiotics. For example, George and Levy initially described a chromosomal multiple antibiotic resistance system which existed in Escherichia coli and which could be selected by a single drug, e.g., tetracycline or chloramphenicol (George and Levy 1983a) . In addition to resistance to the selective agents, the Mar phenotype included resistance to structurally unrelated agents, including nalidixic acid, rifampin, penicillins, and cephalosporins (George and Levy 1983); more recently, resistance to the fluoroguinolones has been described (Cohen et al. 1989) . The expression of a Mar phenotype, conferring substantially increased, simultaneous and coordinated resistance to a multiplicity of structurally unrelated compounds, appears to involve coordinated changes in the expression of a multiplicity of loci. This has been demonstrated in Mar phenotype bacteria of the species E. coli (Cohen et al . 1989). Such coordinated control of the expression of a multiplicity of loci implies the existence of an operon, or operon, which directly or indirectly regulates the expression of the multiplicity of loci directly responsible for the Mar phenotype. One locus in one such operon was identified in E. coli and named marA by George and Levy (George and Levy 1983b). Prior to the present invention, however, no multiple antibiotic resistance ooeron had been isolated or cloned. In addition, no Mar operon had been characterized as to its structure and operation so as to enable the use of such an operon or its fragments for diagnostic, therapeutic or experimental purposes. Finally, the several other contributions to the field of antibacteriology in the claims were unavailable to those skilled in the art prior to the present invention. SUMMARY OF THE INVENTION The present invention relates generally to developing and evaluating antibiotic treatments effective against bacteria possessing a multiple antibiotic resistance operon. Because the expression of such an operon may cause bacteria to become simultaneously resistant to a multiplicity of structurally unrelated antibiotics, it is a general object of the present invention to provide methods and compositions useful in combating bacteria possessing a Mar operon or exhibiting a Mar phenotype. It is one particular object of the present invention to provide tests for compositions which are effective against bacteria expressing a Mar phenotype, which do not induce the expression of a Mar operon, or which inhibit the expression of a Mar operon. To this end, it is also an object of the present invention to provide cloned oligonucleotide sequences, as well as bacterial cells expressing such sequences, which are useful in performing such tests and in investigating bacterial multiple antibiotic resistance operonε. The present invention provides cloned bacterial Mar operonε and cloned portions thereof. In particular, a cloned represser locus and a cloned activator locus of a Mar operon, as well as cloned loci encoding anti-sense transcripts to the represεor and activator loci, are provided. Using such clones, substantially pure represser protein and substantially pure activator protein are provided. In addition, using such clones, substantially pure oligonucleotide sequences, either sense or anti-sense to those loci, are provided. These sequences are useful as probes for substantially homologous loci in other species including bacteria, fungi, parasites, and animal cells and for altering the expression of a Mar phenotype in bacteria, either by encoding repressor or activator proteins or by encoding anti-sense transcripts which inhibit the expression of either a Mar repressor or Mar activator locus. The present invention also provides cloned oligonucleotide sequences in which the regulatory region of a Mar operon has been operably joined to a marker locus. Such sequences are useful in assaying the effect of compositions on the transcription of a Mar operon. The present invention also provides methods for evaluating the antibiotic effectiveness of compositions by assaying their effects upon the transcription of a Mar operon or upon the activity of proteins encoded by a mar operon. In particular, the present invention provides methods for assessing the ability or inability of a composition to inhibit the activity of a Mar repressor, to enhance the activity of a Mar repressor, or to inhibit the activity of a Mar activator. Compositions which enhance the activity of a Mar repressor or inhibit the activity of a Mar activator will be useful either alone or in combination with antibiotics to combat bacteria. A method of treatment for bacterial infections using a combination of such compositions along with antibiotics is thus provided. The present invention also provides methods for evaluating the antibiotic effectiveness of compositions by asεaying their effects on bacteria in which the expression of a Mar operon has been substantially increased and on bacteria in which the expression of a Mar operon has been substantially decreased. To this end, methods of producing εuch bacteria and such bacteria themselves are provided. The present invention also provides tests for identifying loci in bacteria which are subject to regulation, directly or indirectly, by a Mar operon. Because such loci may be involved in the expression of a Mar phenotype, their identification will be useful in developing antibiotic compositions which affect the products or expression of those loci. BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a schematic diagram of SEQ ID NO. 1. DETAILED DESCRIPTION OF THE INVENTION By a locus is understood an oligonucleotide sequence encoding a peptide. A locus consists of a start codon, a stop codon and at least one codon encoding an amino acid residue in between. Typically, a locus is transcribed to produce an mRNA transcript and that transcript is translated to produce a peptide. By regulatory region is understood an oligonucleotide sequence involved in regulating the transcription of one or more loci. Regulatory regions will include a promoter sequence at which an RNA polymerase may bind and, typically, an operator sequence which may be bound by a repressor protein. Additionally, regulatory regions may include enhancers of transcription. By operon is understood one or more loci operably joined to a regulatory region such that, under appropriate conditions, RNA polymerase may bind at a promoter sequence in the regulatory region and proceed to transcribe the loci. The loci within an operon share a common regulatory region and, therefore, are substantially regulated as a unit. Amongst the loci in an operon may be a represεor locus which encodes a repressor protein which, under appropriate conditions, binds to the operator of the operon so as to substantially decrease transcription. By a bacterial multiple antibiotic resistance operon is understood a bacterial operon which, by its expression, affects the expression of one or more different loci, operons or proteins so as to substantially increase resistance to a multiplicity of antibiotics, at least some of which are structurally unrelated. Amongst the loci in a bacterial multiple antibiotic resistance operon, there is at least one locus encoding an activator of a bacterial multiple antibiotic resistance operon. Amongst the loci in a bacterial multiple antibiotic resistance operon, there may also be a locus encoding a repressor of a bacterial multiple antibiotic resistance operon. By a repressor of a bacterial multiple antibiotic resistance operon is understood a protein which, under appropriate conditions, binds to the operator of the operon so as to substantially inhibit the transcription of the operon. Repressor proteins are encoded by repressor loci of bacterial multiple antibiotic resistance operons. By an activator of a bacterial multiple antibiotic resistance operon is understood a protein encoded by a locus within the operon which, under appropriate conditions, affects the expression of one or more loci in different operons or one or more proteins so as to cause expression of a bacterial multiple antibiotic resistance phenotype. By an enhancer of a bacterial multiple antibiotic resistance operon is understood a protein encoded by a locus within the operon which, under appropriate conditions, enhances the expression or activity of an activator of a bacterial multiple antibiotic resistance operon so as to increase expression of a bacterial multiple antibiotic resistance phenotype. By a bacterial multiple antibiotic resistance phenotype is understood simultaneous and coordinated resiεtance to a multiplicity of antibioticε, at leaεt some of which are structurally unrelated, which is substantially increased relative to typical or wild-type bacteria. The antibiotic resistance is coordinated in that the resistance to the multiplicity of antibiotics increases or arises simultaneously and may be decreased or lost simultaneously. By an inducer of a bacterial multiple antibiotic resistance operon is understood a composition which, under appropriate conditions, directly or indirectly inhibits the binding of a repressor of a bacterial multiple antibiotic resistance operon to the regulatory regions of that operon so as to substantially increase the expression of that operon and the expression of a multiple antibiotic resistance phenotype. By a marker locus is understood a locus whose expression is easily assayed. A marker locus is typically a locus encoding an enzyme and the assay may include a substance which changes color in the presence of a product of the enzyme's activity. Alternatively, a marker locus may encode a protein which directly or indirectly affects a visually apparent phenotype of an organism such as color or colony type in bacteria. Alternatively, a marker locus may encode a protein which directly or indirectly confers substantial resistance to, sensitivity to, or dependence upon a particular composition. By the expression of a locus is understood the transcription of the locus to produce mRNA and the translation of the mRNA transcript to produce a peptide. By operable is understood capable of transcription under appropriate conditions in vivo or in vitro. A locus or oligonucleotide sequence is operably joined to a regulatory region if, under appropriate conditions, an RNA polymerase may bind to the promoter of the regulatory region and proceed to transcribe the locus or oligonucleotide sequence in an appropriate reading frame. A locus or oligonucleotide sequence operably joined to a regulatory region is operable. By homology of oligonucleotide sequences is understood a correlation in the nucleotide composition and ordering of the sequences. If the composition and ordering of the nucieotides are the same or substantially the same, the sequences are characterized by "sense" homology. If the composition and ordering of the nucieotides of the sequences are substantially complementary such that the sequences may, under appropriate conditions, hydrogen bond in the manner of complementary strands of DNA, the sequences are characterized by "anti-sense" homology. Sequences characterized by sense homology to the mRNA transcript of a locus may, under appropriate conditions, bind to the DNA of that locus so as to inhibit further transcription. Sequences characterized by antisense homology to the mRNA transcript of a locus may, under appropriate conditions, bind to the DNA of that locus so as to inhibit further transcription or bind to the mRNA transcript of that locus so as to inhibit translation. By an anti-sense locus is understood a locus which encodes an mRNA transcript characterized by substantial anti-sense homology to the mRNA encoded by a specified locus. An anti-sense locus to an activator locus of a bacterial multiple antibiotic resistance operon, for example, will encode an mRNA transcript characterized by substantial anti-sense homology to the mRNA transcript encoded by the activator locus. The anti-sense mRNA may bind to the DNA of the activator locus so as to inhibit further transcription or it may bind to the mRNA transcript of the activator locus so as to inhibit translation. By antibiotic is understood a composition which decreases the viability or which inhibits the growth or reproduction of microbes. As used in this disclosure, for simplicity of exposition, antibiotic is intended to include the term antimicrobial. Thus, antibiotics are intended to embrace antiviral, antifungal and, generally, antimicrobial compositions. The present invention in one aspect provides cloned bacterial multiple antibiotic resistance operons. A bacterial Mar operon may be isolated and cloned from any of a number of species according to the following method. A strain of bacteria is first subjected to selection on solid or in fluid medium containing an antibiotic. The selection may be step-wise, with incrementally increasing concentrations of the antibiotic. Amongst the surviving cells will be spontaneous Mar operon mutants which express the Mar phenotype. Such Mar mutants may be identified by their cross-resistance to a multiplicity of antibiotics structurally unrelated to the selective agent. The approximate map position of the operon may then be determined by mating transfer experiments as are well known in the art. The Mar phenotype bacteria may then be mutagenized with a transposon and cells reverting to the wild-type (non-Mar) phenotype can be isolated by selecting for antibiotic susceptibility on replicated plates. A high percentage of the revertants will be the result of inactivation of the Mar operon by insertion of the transposon within the operon. Using a restriction enzyme known to recognize a site within the transposon, portions of the transposon joined to segments of chromosomal DNA can be cloned into vectors. These clones may, in turn, be used to probe a genomic library of the cells to identify clones bearing at least a portion of the Mar operon. Finally, these clones may be tested for their ability to complement cells in which there is a large deletion around the approximate Mar map position. Clones capable of providing Mar operon activity to the deletantε will contain an operable Mar operon and may be sequenced by standard techniques. (See Example 1. ) In one particular aspect, the present invention provides the cloned wild-type Mar operon of E. coli. One sequence containing a wild-type Mar operon is presented as SEQ ID NO. 1. This sequence has been entered into GenBank with Accesεion 8M96235 and correεpondε to the 7.8kbp fragment isolated in Example l. This sequence or any portion of it may, of course, be cloned into any of a number of vectors which are known to those of ordinary skill in the art. Conservative variations on the DNA sequence SEQ ID NO.l exist which will have no substantial effect on the expression of the operon. The substitution of synonymous codons is one example. A small deletion or insertion which does not disrupt the reading frame is another. Substantially homologous sequences from a Mar operon in a species other than E. coli are another example, particularly when such operons are identified by the methods and compositions disclosed herein. Such conservative variations would be obvious to one of ordinary skill in the art and fall within the spirit and scope of the claims. The sequence of SEQ ID NO. 1 includes three regions. These regions are depicted in Figure 1. The E. coli Mar operon is located in Region II. Analysis of the Mar operon sequence reveals a regulatory region with a promoter-operator sequence, designated marO, and three coding regions designated marR, marA, and marB. The regulatory region marO extends approximately from nucleotide 1231 of SEQ ID NO. l to nucleotide 1502. The first locus, marR, encodes a protein of 125 amino acids, designated the Mar repressor. The marR locus extends from nucleotide 1502 of SEQ ID NO. 1 to nucleotide 1879. The second locus, marA, encodes a protein of 129 amino acids, designated the Mar activator. The marA locus extends from nucleotide 1893 of SEQ ID NO. 1 to nucleotide 2282. The third locus, marB, encodes a protein of 72 amino acids, designated the Mar enhancer. The marB locus extends from nucleotide 2314 of SEQ ID NO. 1 to nucleotide 2531. The Mar repressor acts to repress expression of the operon by binding at marO. The Mar activator acts directly or indirectly to alter the expreεεion of other operonε, loci or proteinε which are directly involved with the expreεεion of the Mar phenotype. The Mar enhancer augmentε the expreεεion of the Mar phenotype. Hybridization εtudieε, disclosed more fully below, indicate that subεtantially homologous sequences are included in the genomes of other bacterial specieε and that bacterial Mar operonε may share a common ancestry and evolutionarily conserved structure. Preliminary investigations have revealed that transcription of Region I proceeds from marO and that the Mar repressor also regulates the levels of expression of Region I. The functions of the putative proteins of Region I are not yet determined. Region III is not under the control of the Mar regulatory region and its expression does not appear to be affected by the Mar repressor. Although the function of the putative protein encoded by Region III is not yet determined, it is clear that Region III is crucial to the expresεion of the Mar phenotype. This has been shown in deletion mutants which possess Regions I and II but not Region III. Such cells cannot express the Mar phenotype. The present invention thus provides cloned portions of these various regions including either regulatory regions, protein coding sequences or both. Particular examples include cloned Mar repressor, Mar activator, and Mar enhancer loci of bacterial Mar operons. The particular examples provided are the cloned E. coli marR, mar , and marB loci. Such loci are cloned preferably so as to be operably joined to a regulatory region so that they may be expressed under conditions wherein the regulatory region is not blocked by a repressor. The loci may be operably joined to a Mar regulatory region or to other regulatory regions depending upon the desired manner of regulation and levels of expression. In addition, the invention provides vectors containing an operably cloned Mar repreεεor locuε without a Mar activator locus and with or without a Mar enhancer locus (see Example 2), an operably cloned Mar activator locus without a Mar repressor locus and with or without a Mar enhancer locus (see Example 3), and an operably cloned Mar enhancer locuε without a Mar repressor locuε and with or without a Mar activator locuε (see Example 3). Given the sequences disclosed herein, as well as the methods provided for identifying subεtantially homologous Mar operons in other species, one of ordinary skill in the art is enabled to produce εuch cloned loci. In addition, anti-sense clones of these loci can be as easily produced and are also an aspect of the present invention. Conservative variations on SEQ ID NO. 1 exist which will have no substantial effect on the expression of these loci. The substitution of synonymous codons is one example. A small deletion or insertion which does not disrupt the reading frame is another. Sequences from a Mar operon in a species other than E. coli are another example, particularly when such operons are identified by the methods and compositions disclosed herein. Such conservative variations would be obviouε to one of ordinary εkill in the art and fall within the spirit and scope of the claims. The present invention also provides probes useful in identifying Mar operons in species other than E. coli. A cloned Mar operon or cloned fragment of a Mar operon from one species can be used to screen a DNA library of another species to identify potential Mar operons by methods which are known to those of ordinary skill in the art. In one preferred embodiment, the cloned E. coli Mar operon disclosed as SEQ ID NO. 1 or a fragment thereof is used to produce probes which are radioactively labeled with 32 P (see Example 4). In a particularly preferred embodiment, the probe is at least a substantial portion of the E. coli marA locus. Such probes may be found to hybridize with DNA extracted from a wide variety of bacteria and perhaps species other than bacteria and may reveal an ancient and highly evolutionarily conserved family of loci and operons. Conservative variations on the disclosed DNA εequence exiεt which will not substantially impair the effectiveness of such probeε. The εubεtitution of a small percentage of the baεes, small insertions, and small deletions are examples. Sequences from a Mar operon in a specieε other than E. coli are another example, particularly when εuch operonε are identified by the methodε and compositions disclosed herein. Such conservative variations would be obvious to one of ordinary skill in the art and fall within the spirit and scope of the claims . The present invention in another aspect provides subεtantially pure Mar repreεsor protein, substantially pure the anti-sense locus is operably joined to a strong promoter and on a high copy-number plasmid such that the anti-sense transcripts are expressed at high levels. For some uses, aε disclosed below, a temperature sensitive plasmid may be preferred. Given the sequences diεcloεed herein, aε well aε the methods provided for identifying subεtantially homologous Mar operons in other species, one of ordinary skill in the art iε enabled to produce such oligonucleotide εequenceε and vectorε operably expressing such sequences. In a preferred embodiment, a strain is created which has a deletion, insertion or substitution in the chromosomal Mar represεor locus such that functional Mar represεor iε not produced but the Mar activator locuε is expressed. In a particularly preferred embodiment, a deletion is introduced. This is achieved by cloning the Mar operon into a temperature senεitive plasmid which replicates at lower temperatures but does not replicate at higher temperatures. Using appropriate restriction enzymes, any one of numerous possible deletions is introduced into the Mar represεor locuε on the plasmid. The plasmid is then introduced into bacterial cells and the cells are grown at the lower temperature to allow for homologous recombination to introduce the partially deleted Mar represεor locuε into the bacterial chromoεome. The bacteria are then grown at the higher temperature εo that, at cell division, the temperature sensitive plaεmid iε loεt from the daughter cells. Cells in which the deletion was introduced into the chromoεome may then be selected with antibiotics. In another preferred embodiment, a Mar activator locus iε introduced within the cells on a vector. In one embodiment, the Mar activator locus iε operably joined to the Mar regulatory region on a plasmid which does not include an operable Mar repressor locus. Homologous recombination is employed, as discloεed above, to inactivate the Mar represεor locus on the chromoεome by partial deletion, insertion, or substitution, so that functional Mar repressor is not levelε. For some uses, as disclosed below, a temperature sensitive plasmid may be preferred. Given the sequences disclosed herein, as well as the methods provided for identifying subεtantially homologous Mar operonε in other species, one of ordinary skill in the art iε enabled to produce such oligonucleotide sequenceε and vectorε operably expreεεing such sequenceε. In another embodiment, a chromoεomal deletion, inεertion or substitution is introduced which iε not in the Mar activator locus but which entails a frameshift upεtream of the locuε such that functional Mar activator protein is not produced. In another preferred embodiment, a strain is created which has a deletion, insertion or substitution in the chromosomal Mar activator locus such that functional Mar activator cannot be produced. In another preferred embodiment, the entire Mar operon or a substantial part of it may be deleted (see Example 7). As discloεed above, such deletions, insertions or substitutionε may be achieved by homologouε recombination between the chromoεomal Mar operon and a properly constructed plasmid. In a most preferred embodiment, a Mar repreεεor locuε is introduced within the cellε on a vector. In thiε embodiment, the Mar repreεεor locuε iε operably joined to a regulatory region other than a Mar regulatory region εuch that it iε expreεεed irreεpective of its own presence. Preferably, the regulatory region will contain a strong promoter and the vectors are high copy-number plasmidε. For some useε, aε disclosed below, it may be preferable that the plasmid be temperature senεitive. Given the εequenceε diεcloεed herein, as well aε the methods provided for identifying subεtantially homologouε Mar operonε in other species, one of ordinary skill in the art iε enabled to produce εuch vectors (see Examples 2 and 3). The present invention also provides an assay for compositionε which induce a Mar phenotype by interfering with the activity of a Mar repressor or which increase the senεitivity of cells to antibiotic compositionε by enhancing the activity of a Mar repressor. In each embodiment, cells which are not characterized by the Mar phenotype are expoεed to a compoεition and then the level of expreεεion of a locuε under the control of a Mar regulatory region iε assayed. The locus may be contained within a Mar operon or may be operably joined to a Mar regulatory region and introduced into the cellε on a vector. In one embodiment, the level of a protein product of a locuε under the control of a Mar regulatory region iε directly measured. This may be accomplished by polyacrylamide gel electrophoresis aε well as other means which are known to those of ordinary skill in the art. In another embodiment, the levels of the mRNA transcript of a locus under the control of a Mar regulatory region are directly measured. This may be accomplished, aε is well known in the art, by performing a Northern hybridization with a probe which has been radioactively labeled with 32P and measuring the level of radioactive probe bound. In a preferred embodiment, the locus is a Mar operon activator locus (see Example 8). Probes for εuch a locuε are disclosed above. In addition, in another preferred embodiment, the locus is at least one of the open reading frames of the E. coli Region I (εee Figure 1) diεcloεed in SEQ ID NO. 1. In a preferred embodiment, a fuεion of a marker locuε to a Mar regulatory region is introduced within the cells. One such fusion is diεcloεed in Example 6. In one embodiment, the marker fuεion of Example 6 iε introduced within cellε and the cellε are then grown in LB broth at 30°C for one hour in the preεence of the compound to be tested. The level of activity of the β-D-galactosidaεe marker can be determined by the O-nitrophenyl-β-D-galactoside assay described in Maniatis, et al . (1982). In each of these embodiments, it is further preferred that a vector bearing an operable Mar repreεεor locuε be introduced within the cells. This will cause increased repreεεion of the Mar operon and improve the ability of the assay to detect inducers of the Mar phenotype. The Mar represεor locuε is preferably introduced into the chromosome by homologous recombination and iε operably joined to a regulatory region other than a Mar regulatory region such that it does not represε it own expression. Such vectors are discloεed above. The moεt preferred embodiment iε an aεεay employing cellε into which have been introduced both a marker locus fused to a Mar regulatory region and an operable Mar represεor locuε which is not controlled by a Mar regulatory region. The present invention also provides assays for compositionε which act to prevent the expression of a Mar phenotype or which cause cells to become even more sensitive to certain compounds than wild-type cells, by acting aε inhibitors of Mar operon expresεion. In each embodiment, cellε which poεεeεε an operable Mar activator locus are exposed to a compoεition and then the level of expreεεion of a locuε, the expreεεion of which is at least in part controlled by Mar operon expreεεion, iε aεεayed. The locus may be naturally occurring in the cells or may be operably joined to a regulatory region influenced by Mar operon expression. Aε discloεed above, the aεεay may be a direct aεεay for a translation product of the locus by, for example, electrophoresis of cellular proteins, for a transcription product of the locus by, for example, a Northern blot of cellular mRNA or, in a preferred embodiment, the locuε iε a marker locuε, the activity of which is easily aεεayed. In a moεt preferred embodiment, a marker locuε is operably joined to the regulatory region of an operon which is affected by Mar operon expreεεion. Meanε of identifying εuch loci are diεclosed below. The fusion of the regulatory region and marker is then introduced into cells. After the cells have been exposed to a composition, changes in the level of expresεion of the marker locuε can be assayed as an within a transpoεon and inεerted within a phage, for example λ: :TnphoA or λ: :TnlacZ, iε introduced into the cells and allowed to randomly integrate into the genome. In addition, it is deεireable that the transpoεon also include a locus conferring resiεtance to kanamycin or another appropriate antibiotic. A number of colonieε, preferably at leaεt five thouεand and, more preferably, at leaεt ten thouεand, are then isolated on plates containing kanamycin or another appropriate antibiotic. These colonies are then examined for expression of the marker locus. If the marker is phoA or lacZ and the cells are grown on plates with 5-bromo-4-chloro-3-indolyl phosphate (XP plates) or 5-bromo-4-chloro-3-indolyl β-D-galactoside (XG plateε), colonieε in which the marker operably inεerted into an actively expreεsed locus will be blue whereas colonies in which the marker failed to insert, inserted inoperably, or inserted operably into a repressed locus will appear white. The colonieε in which the marker iε not expressed are then isolated and the cellε are grown in the preεence of a known inducer of the Mar operon (e.g. εalicylate or tetracycline for E. coli) . Subsequent to such treatment, colonies which expresε the marker (and, in the example, turn blue) are isolated. These colonies contain the marker operably inserted in a locus that is subject to regulation by a Mar operon. The DNA of these colonies may then be fragmented and cloned. Those clones which confer reεistance to kanamycin or another appropriate antibiotic will contain the marker in the tranεpoεon as well as DNA adjacent to the insertion site. The genomic DNA adjacent to the insertion site of the transposon can then be isolated and the locuε into which the tranεposon inserted can be identified by techniques known to those of ordinary εkill in the art. That locuε will, by this method, be identified as one which is involved in the expression of the Mar phenotype. In a most preferred version of the above embodiment, the cells initially express the Mar phenotype but can easily be cauεed to expreεε the non-Mar phenotype. Aε above, a promoterleεε marker in a tranεposon is introduced within the cells and allowed to randomly integrate into the chromoεome. And, as above, the tranεposon also encodeε a locuε conferring reεiεtance to kanamycin or another appropriate antibiotic. A temperature sensitive plaεmid, εuch aε pMAK705 (Hamilton, et al. 1989), bearing an operable Mar activator locuε is introduced within the cells. The plasmid may bear the activator locus operably joined to a Mar regulatory region but without the Mar repressor locus or, preferably, may contain an activator locuε operably joined to a regulatory region other than a Mar regulatory region such that its level of expression iε high. If the Mar activator locus is operably joined to a Mar regulatory region, the chromosomal Mar represεor locuε muεt be inactivated by any of the meanε disclosed above. In addition, the chromosomal Mar activator locus is inactivated by any of the means diεclosed above εo that the expreεεion of the Mar phenotype is dependent upon the plasmid, and the cellε are recombination deficient (e.g. recA ) εo that the activator locus on the plasmid cannot be introduced into the chromoεome. Initially, the cells are grown at a temperature at which the temperature sensitive plasmid replicateε (e.g. 30°C for pMA 705) and in the preεence of kanamycin or another appropriate antibiotic. In this embodiment, a number of colonies, preferably at leaεt five thousand and, more preferably, at least ten thouεand, are then iεolated and examined for expreεεion of the marker locuε. If the marker is phoA or lacZ and the cells are grown on X-P or X-G plateε, for example, colonies in which the marker operably inserted into an actively expreεεed locus will be blue whereas colonies in which the marker failed to insert, inεerted inoperably, or inεerted operably into a repreεεed locuε will appear white. The colonieε in which the marker iε expreεεed are then isolated and the cells are grown at an elevated temperature (e.g. 42°C for pKAK705) such that the temperature εenεitive plaεmid and, consequently, the pUC18. Two clones, designated pKanl and pKan2 (see Hachler, Cohen and Levy, 1991), were isolated which contained the 3.2kbp of Tn5 upstream of its internal BamHI site. A 2kbp Hpal fragment of pKanl, containing only 187bp from the IS50L of Tn5 and 1.85kbp of chromoεomal DNA was used as a probe to screen a λ phasmid library derived from partial Sau3A digestε of the E. coli K12 derivative W3110 (εee Elledge and Walker, 1985). Iεolation was performed in host strain PLK1738 in which the marA region has been deleted. Two phasmidε identified by the probe were introduced by tranεduction into a deletion strain HH84 in which the region including the Mar operon had been deleted from the chromosome. These phasmids were capable of reεtoring Mar operon activity. One of the fragments, 13. lkbp in length, was used for subcloning into the low copy-number vector pHSG415. Mar activity waε teεted in CH164, a ΔmarA εtrain genetically related to the original AG100 Mar mutants. Subcloneε containing either the 9kbp Pεtl or 7.8kbp Hpal-PstI fragment, but none containing any smaller fragments, produced Mar mutants. (For detail on the genotypes of the strains and vectors, see Hachler, Cohen, and Levy, 1991, incorporated herein by reference.) Example 2 The Mar represεor locuε, marR, was cloned from the wild-type plasmid pHHM183 (εee Hachler, Cohen and Levy, 1991) aε an 818bp Dral fragment into the Smal site of the high copy-number cloning vector pUC18. The plasmid was designated pl25WT. A mutant Mar represεor locus causing expreεεion of the Mar phenotype waε cloned on a 850bp Dral-Hpal fragment from plaεmid pKanl (see Hachler, Cohen and Levy, 1991) into pUC18. This plaεmid waε deεignated pl25Mar. Theεe plaεmids have been introduced into a number of E. coli K12 εtrainε εuch aε the wild-type AG100 and Mar mutant AG102. The full genotypeε of theεe strains may be found in Cohen et al . , 1988, incorporated herein by reference. Example 3 The entire E. coli Mar operon, marA, and marB have been cloned into various vectors and introduced within various hostε uεing the diεclosed sequences and the polymerase chain reaction to generate the fragments diεcloεed below. In particular, for cloning the entire operon, the PCR primers at the 5' end were nucieotides 1311-1328 of SEQ ID NO. 1 and nucieotides 2575-2592 at the 3' end. In addition Pεtl linkerε were included at both endε. For cloning the marA locus, the PCR primers were nucleotideε 1893-1908 at the 5' end and nucleotideε 2265-2282 at the 3' end with EcoRI linkers at both ends. For cloning the marB locuε, the PCR primerε were nucleotideε 2314-2331 at the 5' end and nucieotides 2515-2532 at the 3' end with EcoRI linkerε at both ends. The PCR synthesized genes have been cloned into εeveral plasmid vectors at appropriate single restriction enzyme sites: pUC18, a multicopy ColEl derivative; pMAK705, a temperature-senεitive plasmid described in Hamilton et al. , 1989; and pMAL-C2, a plasmid used for expressing the protein fused to MalE (New England BioLabs, Beverly, Mass., product #800). The plasmidε have been introduced in wild-type E. coli K12; AG102, a Mar mutant described in George and Levy, 1983b; AG1025, a marA: :Tn5 Mar revertant deεcribed in George and Levy 1983b; and CH164, a Mar deleted εtrain deεcribed in Hachler, Cohen and Levy, 1991. Example 4 Cloned copieε of SEQ ID NO. 1 were digeεted with BεpHI . A reεulting 1.24kbp fragment, correεponding to nucieotides 1073 to 2314 of SEQ ID NO. 1 waε uεed to produce 32P labelled probes. DNA extracted from a large number of bacterial species were tested for homology to this probe under stringent DNA: :DNA hybridization techniqueε uεing dot blotε and Southern hybridization methodε, aε are well known to thoεe of ordinary εkill in the art (εee, e.g., Maniatiε, Fritch and Sambrook, 1982, incorporated herein by reference). DNA from the following gram-negative genera were found to hybridize with the probe: Citrobacter, Enterobacter, Eεcherichia, Hafnia, Klebsiella, Salmonella, and Shiqella. Two species, Enterobacter agqlomerans and Salmonella sp. , were further tested. Theεe were found to produce Mar phenotype mutantε when εelected by the same regime employed with E. coli and to produce a 1.4kb mRNA transcript at heightened levels. The 1.4kb transcripts were the same size as and homologous to the mRNA produced at heightened levels in E. coli expresεing the Mar phenotype. Example 5 The E. coli marA fragment deεcribed in Example 3 waε cloned into pMAL-C2, a vector bearing the maltose binding protein locus, MalE. This vector is commercially available as part of a kit for protein purification ("Protein fusion and purification system," New England BioLabs, Beverly, Mass., product #800). The clone, including the marA fragment, encoded a fusion product comprising the Mar activator protein and the maltose binding protein linked by a peptide which is cleavable by protease Xa. The fuεion protein waε made in E. coli TB1 (ara, Δ(lac pro AB) rpεL (Φ8Q lacZ AMI5) hεdR) . The fuεion protein waε then εubstantially purified by amylose column chromatography. The peptide linking the Mar activator protein and the maltoεe binding protein waε cleaved and the εubεtantially purified Mar protein collected. Example 6 A 405bp Thai fragment containing the E. coli marO region was ligated into the Smal site of pMLB1109, a lacZ transcriptional fuεion plaεmid. The reεulting plaεmid conεtruct had lacZ gene expreεεion under the control of the marO promoter. The fuεion was introduced into the chromosome of a wild type cell and a Mar operon deleted εtrain. Thiε waε accompliεhed by firεt introducing the marO-lacZ region of the fuεion plaεmids, by homologous recombination, into the genome of phage λRZ5 by infecting an E. coli K12 strain designated SPC103 (M4100 (Mac U169 araD, rpsL, relA, thi, fibB) deleted of 39kbp εurrounding the Mar operon) bearing one of the fuεion plaεmidε, with λRZ5. The resulting lysate waε used to transduce plasmid-less SPC103. Amp R, Lac+ lysogens were εelected on LB agar containing ampicillin (50 μg/ml) and 5-bromo-4-chloro-3-indolyl β-D-galactoεidaεe. Lyεateε from theεe purified lyεogenε were then uεed to infect E. coli MC4100 or SPC103 and Amp R, Lac+ lyεogenε were again isolated. The resulting strains, SPC104, SPC105, SPC106, and SPC107 were confirmed to have a single copy of the fusion region located in the εame εite on the chromoεome (likely the att εite) by Southern hybridization of Pstl-digested chromosomal DNA from the strains with a 405bp EcoRI/BamHI fragment. Lysogenε of MC4100 (SPC104, SPC105) had 2 bands which hybridized with a 9kb fragment representing the naturally occurring marO-marA sequence and a larger fragment (>15kb) representing the inεertion of the marO-lacZ fuεion phage into the chromoεome. The lysogens of the Mar deletion strain SPC103 (SPC106, SPC107) contained only chromosomal sequences corresponding to the larger band. DNA manipulations and analyseε were performed according to Maniatiε et al . (1982). Aεsays for β-galactosidaεe activity were performed on cellε grown for one hour to mid-logarithmic phaεe in LB broth in the preεence of known and potential inducerε of the Mar phenotype at 30° C. The β-galactosidase activity of these cells was compared to cells grown εimilarly but in the abεence of known inducerε of the Mar phenotype. Example 7 A 9kbp Pεtl fragment of E. coli K12 chromosomal DNA containing the Mar operon waε cloned into temperature- sensitive plasmid pMA 705. The plaεmid replicateε at 30°C but iε loεt from daughter cellε during cellε diviεion at 42°C. Uεing BspHI , a 1.24kbp deletion corresponding to nucleotide 1073 to nucleotide 2314 of SEQ ID NO. 1 and including all of the marO region, the marR and marA loci, and part of the marB locus was made within the Mar operon on the plasmid. The plaεmid was then introduced within E. coli K12 AG100 (see George and Levy, 1983b for genotype information). The plasmid and chromosome were then allowed to undergo homologouε recombination and the cellε were cured of the plaεmid at 42 C. A recombinant εtrain with the 1.24kbp deletion in the chromosomal Mar operon was isolated and deεignated AG100 Δ15. Example 8 About 10 8 E. coli which were not expreεεing the Mar phenotype were grown at 30°C, collected at the end of logarithmic phase and reεuεpended in freεh broth containing εalicylate, a known Mar operon inducer, for one hour at 30°C. The mRNA waε extracted from theεe cellε and εeparated by gel electrophoreεiε. A 1.24kb BspHI fragment from within the Mar operon which includes the marA locuε was labeled with 32 P by random priming and used as a probe in a Northern hybridization to aεεay for increaεed expression of the marA locuε. SEQUENCE LISTING (1) GENERAL INFORMATION (i) APPLICANT (A) NAME: TRUSTEES OF TUFTS COLLEGE (B) STREET: Blue Hall, 4th Floor (C) CITY: Medford (D) STATE: Massachusetts (E) COUNTRY: United States of America (F) ZIP: 02155 (G) TELEPHONE: 617-627-3320 (ii) TITLE OF INVENTION: MULTIPLE ANTIBIOTIC RESISTANCE OPERON ASSAYS (iii) NUMBER OF SEQUENCES: 1 (iv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: Wolf, Greenfield & Sacks, P.C. (B) STREET: 600 Atlantic Avenue (C) CITY: Boston (D) STATE: Massachusetts (E) COUNTRY: United States of America (F) ZIP: 02210 (v) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Diskette, 3.50 inch (B) COMPUTER: IBM-compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: WordPerfect 5.1 (vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER: not available (B) FILING DATE: herewith (vii) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: 07/938,085 (B) FILING DATE: 28 AUGUST 1992 (viii) ATTORNEY/AGENT INFORMATION: (A) NAME: GATES, Edward R. (B) REGISTRATION NUMBER: 31,616 (C) REFERENCE/DOCKET NUMBER: T0359/7001WO (ix) TELECOMMUNICATION INFORMATION: (A) TELEPHONE: (617) 720-3500 (B) TELEFAX: (617) 720-2441 (C) TELEX: 92-1742 EZEKIEL (2) INFORMATION FOR SEQ ID NO: 1: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7876 base pairs (B) TYPE: nucleotide (C) STRANDEDNESS: double (D) TOPOLOGY: circular (ii) MOLECULE TY?E: Genomic DNA (iii) HYPOTHETICAL: no (iv) ANTI-SENSE: no (vi) ORIGINAL SOURCE: (A) ORGANISM: Escherichia coli (B) STRAIN: K-12 (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1: AGC ATT TTG GAC TGG ATC GAG GAC AAC CTG GAA TCG CCA CTG TCA CTG 1982 Ser He Leu Asp Trp He Glu Asp Asn Leu Glu Ser Pro Leu Ser Leu 15 20 25 30 GAG AAA GTG TCA GAG CGT TCG GGT TAC TCC AAA TGG CAC CTG CAA CGG 2030 Glu Lys Val Ser Glu Arg Ser Gly Tyr Ser Lys Trp His Leu Gin Arg 35 40 45 ATG TTT AAA AAA GAA ACC GGT CAT TCA TTA GGC CAA TAC ATC CGC AGC 2078 Met Phe Lys Lys Glu Thr Gly His Ser Leu Gly Gin Tyr He Arg Ser 50 55 60 CGT AAG ATG ACG GAA ATC GCG CAA AAG CTG AAG GAA AGT AAC GAG CCG 2126 Arg Lys Met Thr Glu He Ala Gin Lys Leu Lys Glu Ser Asn Glu Pro 65 70 75 ATA CTC TAT CTG GCA GAA CGA TAT GGC TTC GAG TCG CAA CAA ACT CTG 2174 He Leu Tyr Leu Ala Glu Arg Tyr Gly Phe Glu Ser Gin Gin Thr Leu 80 85 90 ACC CGA ACC TTC AAA AAT TAC TTT GAT GTT CCG CCG CAT AAA TAC CGG 2222 Thr Arg Thr Phe Lys Asn Tyr Phe Asp Val Pro Pro His Lys Tyr Arg 95 100 105 110 ATG ACC AAT ATG CAG GGC GAA TCG CGC TTT TTA CAT CCA TTA AAT CAT 2270 Met Thr Asn Met Gin Gly Glu Ser Arg Phe Leu His Pro Leu Asn His 115 120 125 TAGTTGAAAA CGTGACAACG TCACTGAGGC AATC ATG AAA CCA 2322 Met Lys Pro 1 GCA ATA GCA GCT GCG CTT ATT CTC TTT TCC GCG CAG GGC 2370 Ala He Ala Ala Ala Leu He Leu Phe Ser Ala Gin Gly 10 15 CAG CCA GTT GTT ACT TCT TGT GCC AAT GTC 2418 Gin Pro Val Val Thr Ser Cys Ala Asn Val 30 35 CAG GAA CAC CCA CCG TTT GAT TTA AAT CAC 2466 Gin Glu His Pro Pro Phe Asp Leu Asn His 45 50 AAG TCG GAT GCG CTC GGC GTG CCC TAT TAT 2514 Lys Ser Asp Ala Leu Gly Val Pro Tyr Tyr 60 65 AAT CAA CAC GCT ATG TAGTTTGTTC TGGCCCCGAC ATCTCGGGGC TTATTAACTT 2569 Asn Gin His Ala Met 70 CCCACCTTTA CCGCTTTACG CCACCGCAAG CCAAATACAT TGATATACAG CCCGGTCATA 2629 ATGAGCACCG CACCTAAAAA TTGCAGACCC GTTAAGCGTT CATCCAACAA TAGTGCCGCA 2689 CTTGCCAGTC CTACTACGGG CACCAGTAAC GATAACGGTG CAACCCGCCA GGTTTCATAG 2749 GTCCCAGTA ACGTCCCCCA GATCCCATAA CCAACAATTG TCGCCACAAA CGCCAGATAC 2809 ATCAGAGACA AGATGGTGGT CATATCGATA GTAACCAGAC TGTGAATCAT GGTTGCGGAA 2869 CATCGAGAA TCAGCGAGG AACAAAGAAG GGAATGATTG GGATTAAAGC GCTCCAGATT 2929 ACCAGCGACA TCACCGCCGG ACGCGTTGAG TGCGACATGA TCTTTTTATT GAAGATGTTG 2989 CCACACGCCC AACTAAATGC TGCCGCCAGG GTCAACATAA AGCCGAGCAT CGCCACATGC 3049 TGACCGTTCA GACTATCTTC GATTAACACC AGTACGCCAA AAATCGCTAA GGCGATCCCC 3109 GCCAATTGTT TGCCATGCAG TCGCTCCCCG AAAGTAAACG CGCCAAGCAT GATAGTAAAA 3169 AACGCCTGTG CCTGTAACAC CAGCGAAGCC AGTCCAGCAG GCATACCGAA GTTAATGGCA 3229 CAAAAAAGAA AAGCAAACTG CGCAAAACTG ATGGTTAATC CATACCCCAG CAGCAAATTC 3289 AGTGGTACTT TCGGTCGTGC GACAAAAAAG ATAGCCGGAA AAGCGACCAG CATAAAGCGC 3349 AAACCGGCCA GCATCAGCGT GGCATGTTAT GAAGCCCCAC TTTGATGACC ACAAAATTTA 3409 GCCCCCATAC GACCACTACC AGTAGCGCCA ACACCCCATC TTTTCGCGAC ATTCTACCGC 3469 CTCTGAATTT CATCTTTTGT AAGCAATCAA CTTAGCTGAA TTTACTTTTC TTTAACAGTT 3529 GATTCGTTAG TCGCCGGTTA CGACGGCATT AATGCGCAAA TAAGTCGCTA TACTTCGGAT 3589 TTTTGCCATG CTATTTCTTT ACATCTCTAA AACAAAACAT AACGAAACGC ACTGCCGGAC 3649 AGACAAATGA ACTTATCCCT ACGACGCTCT ACCAGCGCCC TTCTTGCCTC GTCGTTGTTA 3709 TTAACCATCG GACGCGGCGC TACCGTGCCA TTTATGACCA TTTACTTGAG TCGCCAGTAC 3769 AGCCTGAGTG TCGATCTAAT CGGTTATGCG ATGACAATTG CGCTCACTAT TGGCGTCGTT 3829 TTTAGCCTCG GTTTTGGTAT CCTGGCGGAT AAGTTCGACA AGAAACGCTA TATGTTACTG 3889 GCAATTACCG CCTTCGCCAG CGGTTTTATT GCCATTACTT TAGTGAATAA CGTGACGCTG 3949 GTTGTGCTCT TTTTTGCCCT CATTAACTGC GCCTATTCTG TTTTTGCTAC CGTGCTGAAA 4009 GCCTGGTTTG CCGACAATCT TTCGTCCACC AGCAAAACGA AAATCTTCTC AATCAACTAC 4069 ACCATGCTAA ACATTGGCTG ACCATCGGTC CGCCGCTCGG CACGCTGTTG GTAATGCAGA 4129 GCATCAATCT GCCCTTCTGG CTGGCAGCTA TCTGTTCCGC GTTTCCCATG CTTTTCATTC 4189 AAATTTGGGT AAAGCGCAGC GAGAAAATCA TCGCCACGGA AACAGGCAGT GTCTGGTCGC 4249 CGAAAGTTTT ATTACAAGAT AAAGCACTGT TGTGGTTTAC CTGCTCTGGT TTTCTGGCTT 4309 CTTTTGTAAG CGGCGCATTT GCTTCATGCA TTTCACAATA TGTGATGGTG ATTGCTGATG 4369 GGGATTTTGC CGAAAAGGTG GTCGCGGTTG TTCTTCCGGT GAATGCTGCC ATGGTGGTTA 4429 CGTTGCAATA TTCCGTGGGC CGCCGACTTA ACCCGGCTAA CATCCGCGCG CTGATGACAG 4489 CAGGCACCCT CTGTTTCGTC ATCGGTCTGG TCGGTTTTAT TTTTTCCGGC AACAGCCTGC 4549 TATTGTGGGG TATGTCAGCT GCGGTATTTA CTGTCGGTGA AATCATTTAT GCGCCGGGCG 4609 AGTATATGTT GATTGACCAT ATTGCGCCGC CAGAAATGAA AGCCAGCTAT TTTTCCGCCC 4669 AGTCTTTAGG CTGGCTTGGT GCCGCGATTA ACCCATTAGT GAGTGGCGTA GTGCTAACCA 4729 GCCTGCCGCC TTCCTCGCTG TTTGTCATCT TAGCGTTGGT GATCATTGCT GCGTGGGTGC 4789 TGATGTTAAA AGGGATTCGA GCAAGACCGT GGGGGCAGCC CGCGCTTTGT TGATTTAAGT 4849 CGAACACAAT AAAGATTTAA TTCAGCCTTC GTTTAGGTTA CCTCTGCTAA TATCTTTCTC 4909 ATTGAGATG AAATTAAGGT AAGCGAGGAA ACACACCACA CCATAAACGG AGGCAAATAA 4969 TGCTGGGTAA TATGAATGTT TTTATGGCCG TACTGGGAAT AATTTTATTT TCTGGTTTTC 5029 TGGCCGCGTA TTTCAGCCAC AAATGGGATG ACTAATGAAC GGAGATAATC CCTCACCTAA 5089 CCGGCCCCTT GTTACAGTTG TGTACAAGGG GCCTGATTTT TATGACGGCG AAAAAAAACC 5149 GCCAGTAAAC CGGCGGTGAA TGCTTGCATG GATAGATTTG TGTTTTGCTT TTACGCTAAC 5209 AGGCATTTTC CTGCACTGAT AACGAATCGT TGACACAGTA GCATCAGTTT TCTCAATGAA 5269 TGTTAAACGG AGCTTAAACT CGGTTAATCA CATTTTGTTC GTCAATAAAC ATGCAGCGAT 5329 TTCTTCCGGT TTGCTTACCC TCATACATTG CCCGGTCCGC TCTTCCAATG ACCACATCCA 5389 GAGGCTCTTC AGGAAATGCG CGACTCACAC CTGCTGTCAC GGTAATGTTG ATATGCCCTT 5449 CAGAATGTGT GATGGCATGG TTATCGACTA ACTGGCAAAT TCTGACACCT GCACGACATG 5509 CTTCTTCATC ATTAGCCGCT TTGACAATAA TGATAAATTC TTCGCCCCCG TAGCGATAAA 5569 CCGTTTCGTA ATCACGCGTC CAACTGGCTA AGTAAGTTGC CAGGGTGCGT AATACTACAT 5629 CGCCGATTAA ATGCCCGTAG TATCATTAAC CAATTTAAAT CGGTCAATAT CCAACAACAT 5689 TAAATAAAGA TTCAGAGGCT CAGCGTTGCG TAACTGATGA TCAAAGGATT CATCAAGAAC 5749 CCGACGACCC GGCAATCCCG TCAAAACATC CATATTGCTA CGGATCGTCA GCAAATAAAT 5809 TTTGTAATCG GTTAATGCCG CAGTAAAAGA AAGCAACCCC TCCTGAAAGG CGTCGAAATG 5869 CGCGTCCTGC CAGTGATTTT CAACAATAGC CAGCATTAAT TCCCGACCAC AGTTATGCAT 5929 ATGTTGATGG GCAGAATCCA TTAGCCGAAC GTAAGGTAAT TCATCGTTAT CGAGTGGCCC 5989 CAGATGATCA ATCCACCGAC CAAACTGGCA CAGTCCATAA GAATGGTTAT CCGTTATTTC 6049 TGGCTTACTG GCATCTCTCG CGACCACGCT GTGAAACATA CTCACCAGCC ACTGGTAGTG 6109 GGCATCGATA GCCTTATTGA GATTTAACAA GATGGCATCA ATTTCCGTTG TCTTCTTGAT 6169 CATTGCCACT CCTTTTTCAC AGTTCCTTGT GCGCGCTATT CTAACGAGAG AAAAGCAAAA 6229 TTACGTCAAT ATTTTCATAG AAATCCGAAG TTATGAGTCA TCTCTGAGAT AACATTGTGA 6289 TTTAAAACAA AATCAGCGAA TAAAAAAGTG TTTAATTCTG TAAATTACCT CTGCATTATC 6349 GTAAATAAAA GGATGACAAA TAGCATAACC CAATACCCTA ATGGCCCAGT AGTTCAGGCC 6409 ATCAGGCTAA TTTATTTTTA TTTCTGCAAA TGAGTGACCC GAACGACGGC CGGCGCGCTT 6469 TTCTTATCCA GACTGCCACT AATGTTGATC ATCTGGTCCG GCTGAACTTC TCGTCCATCA 6529 AAGACGGCCG CAGGAATAAC GACATTAATT TCACCGCTCT TATCGCGAAA AACGTAACGG 6589 TCCTCTCCTT TGTGAGAAAT CAAATTACCG CGTAGTGAAA CCGAAGCGCC ATCGTGCATG 6649 GTTTTTGCGA AATCAACGGT CATTTTTTTT GCATCATCGG TTCCGCGATA GCCATCTTCT 6709 ATTGCATGAG GCGGCGGTGG CGCTGCATCC TGTTTTAAAC CGCCCTGGTC ATCTGCCAAC 6769 GCATAAGGCA TGACAAGAAA ACTTGCTAAT ACAATGGCCT GAAATTTCAT ACTAACTCCT 6829 TAATTGCGTT TGGTTTGACT TATTAAGTCT GGTTGCTATT TTTATAATTG CCAAATAAGA 6889 ATATTGCCAA TTGTTATAAG GCATTTAAAA TCAGCCAACT AGCTGTCAAA TATACAGAGA 6949 ATTTAACTCA CTAAAGTTAA GAAGATTGAA AAGTCTTAAA CATATTTTCA GAATAATCGG 7009 ATTTATATGT TTGAAAATTA TTATATTGGA CGAGCATACA GAAAAAGCAA ATCACCTTTA 7069 CATATAAAAG CGTGGACAAA AAACAGTGAA CATTAATAGA GATAAAATTG TACAACTTGT 7129 AGATACCGAT ACTATTGAAA ACCTGACATC CGCGTTGAGT CAAAGACTTA TCGCGGATCA 7189 ATTACGCTTA ACTACCGCCG AATCATGCAC CGGCGGTAAG TTGGCTAGCG CCCTGTGTGC 7249 AGCTGAAGAT ACACCCAAAT TTTACGGTGC AGGCTTTGTT ACTTTCACCG ATCAGGCAAA 7309 GATGAAAATC CTCAGCGTAA GCCAGCAATC TCTTGAACGA TATTCTGCGG TGAGTGAGAA 7369 AGTGGCAGCA GAAATGGCAA CCGGTGCCAT AGAGCGTGCG GATGCTGATG TCAGTATTGC 7429 CATTACCGGC TACGGCGGAC CGGAGGGCGG TGAAGATGGT ACGCCAGCGG GTACCGTCTG 7489 GTTTGCGTGG CATATTAAAG GCCAGAACTA CACTGCGGTT ATGCATTTTG CTGGCGACTG 7549 CGAAACGGTA TTAGCTTTAG CGGTGAGGTT TGCCCTCGCC CAGCTGCTGC AATTACTGCT 7609 ATAACCAGGC TGGCCTGGCG ATATCTCAGG CCAGCCATTG GTGGTGTTTA TATGTTCAAG 7669 CCACGATGTT GCAGCATCGG CATAATCTTA GGTGCCTTAC CGCGCCATTG TCGATACAGG 7729 CGTTCCAGAT CTTCGCTGTT ACCTCTGGAA AGGATCGCCT CGCGAAAACG CAGCCCATTT 7789 TCACGCGTTA ATCGCCCTGC TCAACAAACC ACTGATAACC ATCATCGGCC AACATTTGCG 7849 TCCACAGATA AGCGTAATAA CCTGCAG 7876

Claims: CLAIMS 1. A method for predicting the antibiotic effectiveness of a composition comprising exposing bacteria to said composition and assaying the effect of said exposure on the expresεion of a genetic locus wherein said expresεion iε regulated at leaεt in part and at leaεt indirectly by at least a portion of a regulatory region of a bacterial multiple antibiotic resistance operon within said bacteria. 2. A method as in claim 1 wherein said assay comprises a determination of the levels of a transcription product of said genetic locus. 3. A method as in claim 1 wherein said assay compriseε a determination of the levelε of a tranεlation product of εaid genetic locus. 4. A method as in claim 1 further comprising introducing within said bacteria an oligonucleotide sequence, εaid sequence including at least a portion of a regulatory region of a bacterial multiple antibiotic reεiεtance operon operably joined to a marker locuε εuch that the expreεsion of said marker locus is subεtantially dependent upon said portion of said regulatory region, and wherein εaid genetic locuε iε εaid marker locuε and said asεay iε for the expression of said marker locuε. 5. A method aε in claim 4 wherein εaid marker locuε is a sequence encoding an enzyme. 6. A method aε in claim 5 wherein εaid marker locuε iε a sequence encoding at least a portion of a bacterial beta-galactosidase. 7. A method as in claim 4 further comprising introducing within said bacteria an operable oligonucleotide sequence encoding at least a portion of a repressor of said bacterial multiple antibiotic resistance operon, wherein said portion of said repressor is capable of substantially inhibiting the expression of a bacterial multiple antibiotic resistance operon, and wherein said asεay is for increased expression of said genetic locus. 8. A method as in claim 4 wherein, prior to said exposure, said bacteria effectively express a multiple antibiotic resistance phenotype and wherein said asεay is for decreased expression of said genetic locuε. 9. A method of predicting the antibiotic effectiveneεε of a compoεition compriεing expoεing a strain of bacteria to said composition and determining the effects of said compoεition on the growth of εaid bacteria wherein, prior to εaid exposure, said εtrain of bacteria haε been treated so as to subεtantially decreaεe expreεsion of a multiple antibiotic resistance operon. 10. A method as in claim 9 wherein εaid operon haε been at leaεt partially deleted in εaid bacteria εuch that the expreεsion of an activator locuε of εaid operon iε εubstantially decreased. 11. A method as in claim 9 wherein said strain of bacteria has been genetically altered, said alteration comprising introducing within said bacteria an operable oligonucleotide sequence encoding at least a portion of a represεor of εaid operon wherein said portion of said repressor is capable of substantially inhibiting the expresεion of said operon. 12. A method as in claim 9 wherein said strain of bacteria has been genetically altered, said alteration comprising introducing within said bacteria an operable oligonucleotide sequence encoding an mRNA transcript characterized by substantial homology to a least a portion of an activator locus of said operon such that said mRNA transcript substantially inhibits the expression of εaid activator locuε. 13. A method aε in claim 9 wherein said strain of bacteria has been genetically altered, said alteration comprising, introducing within εaid bacteria a transposon such that εaid tranεpoεon insertε within an activator locuε of εaid operon. 14. A method of predicting the antibiotic effectiveness of a composition comprising expoεing a εtrain of bacteria to εaid compoεition and determining the effects of said composition on said bacteria wherein, prior to said exposure, said strain of bacteria has been treated so as to subεtantially increase the expression of a bacterial multiple antibiotic resistance operon. 15. A method as in claim 14 wherein said operon has been at least partially deleted in εaid bacteria. 16. A method as in claim 14 wherein said strain of bacteria has been genetically altered, said alteration comprising introducing within said bacteria an operable oligonucleotide sequence encoding at least a portion of an activator of εaid operon wherein said portion is capable of substantially increasing the expression of a bacterial multiple antibiotic reεiεtance phenotype. 17. A method aε in claim 14 wherein said strain of bacteria haε been genetically altered, said alteration compriεing introducing within εaid bacteria an operable oligonucleotide sequence encoding an mRNA transcript that iε characterized by substantial homology to a least a portion of a repressor locus of said operon such that said mRNA transcript substantially inhibits the expression of said represεor locuε. 18. A method aε in claim 1 further compriεing introducing within εaid bacteria an oligonucleotide sequence, said sequence including a marker locus operably joined to at least a portion of a regulatory region of a bacterial operon such that the expresεion of said marker locuε iε εubεtantially dependent upon said portion of a regulatory region of εaid bacterial operon, wherein the expreεεion of εaid bacterial operon iε regulated at leaεt in part by expreεεion of a bacterial multiple antibiotic resistance operon. 19. A method aε in claim 18 wherein said bacteria express a multiple antibiotic resistance phenotype. 20. A method as in claim 18 wherein at least a portion of a represεor locuε of εaid operon haε been deleted such that εaid bacteria express a multiple antibiotic resistance phenotype. 21. A method as in claim 18 further comprising introducing within said bacteria an operable oligonucleotide sequence encoding at least a portion of an activator of said bacterial multiple antibiotic resiεtance operon wherein εaid portion iε capable of substantially increasing the expression of a bacterial multiple antibiotic resiεtance phenotype. 22. A method aε in claim 21 wherein at leaεt a portion of a repreεsor locus of said operon has been deleted such that said bacteria expreεε a multiple antibiotic resistance phenotype. 23. A method as in claim 18 further compriεing introducing within εaid bacteria an operable oligonucleotide εequence encoding an mRNA tranεcript characterized by subεtantial homology to at leaεt a portion of a repreεεor locuε of εaid operon εuch that said mRNA tranεcript substantially inhibits the expreεεion of said repreεεor locus. 24. A method as in claim 22 wherein said marker locus encodes at least a portion of a bacterial beta-galactoεidase and said bacterial operon is at least a portion of a bacterial micF operon. 25. A method of inhibiting the growth of bacteria comprising expoεing εaid bacteria to a compoεition including amount of an antibiotic composition and amount of a substance which inhibits the expreεsion of a multiple antibiotic resistance phenotype by said bacteria. 26. A method as in claim 25 wherein said substance is an oligonucleotide sequence compriεing at leaεt a portion of a repreεsor locus of a bacterial multiple antibiotic resistance operon operably joined to a regulatory region such that the expression of said represεor locus is substantially dependent upon εaid portion of a regulatory region and said sequence is free from operable sequences encoding an activator of a bacterial multiple antibiotic resiεtance operon. 27. A method as in claim 25 wherein said subεtance iε an oligonucleotide εequence characterized by substantial homology to at least a portion of an activator locus of a bacterial multiple antibiotic resistance operon. 28. A method as in claim 25 wherein said subεtance iε an inhibitor of the activity of an activator of a bacterial multiple antibiotic reεiεtance operon. 29. A method of identifying bacterial loci which affect reεiεtance to antibiotic compoεitions comprising allowing an activator of a bacterial multiple antibiotic resistance operon to bind to a bacterial DNA molecule and asεaying for εiteε on said DNA to which said activator bindε . 30. A method aε in claim 29 wherein εaid DNA haε been fragmented and εaid assay is in vitro. 31. A method of identifying bacterial loci which affect resistance to antibiotic compositions comprising introducing within said bacteria an operable oligonucleotide εequence encoding at least a portion of an activator of a bacterial multiple antibiotic resistance operon wherein said portion of εaid activator iε capable of εubεtantially increaεing the expreεεion of a bacterial multiple antibiotic reεistance phenotype, and asεaying for changes in the levels of expreεεion of genetic loci within εaid bacteria. 32. A method of identifying bacterial loci which affect resiεtance to antibiotic compoεitions comprising subjecting bacteria to a first set of conditions such that said bacteria express a multiple antibiotic resiεtance phenotype, introducing within said bacteria an oligonucleotide sequence including a marker locus and free of a regulatory region operably joined to said marker locuε, permitting said sequence to integrate at random siteε within a chromoεome of εaid bacteria, aεεaying for expression of said marker locus, subjecting a subset of said bacteria which expresε εaid marker locuε to a second set of conditions such that said subεet of bacteria do not expreεε said phenotype; asεaying for bacteria in εaid subset of bacteria which do not expresε εaid marker locuε under εaid second set of conditions, and determining said site of integration of said marker locus in εaid subset of bacteria which expresε said marker locus under said first set of conditions and which do not expreεε εaid marker locuε under said second set of conditionε 33. A method aε in claim 32 wherein said first set of conditionε compriεeε introducing within εaid bacteria a temperature εenεitive plaεmid including an operable oligonucleotide εequence encoding at leaεt a portion of an activator of a bacterial multiple antibiotic reεiεtance operon, wherein εaid portion of εaid activator iε capable of εubεtantially increaεing the expreεεion of a bacterial multiple antibiotic reεiεtance phenotype, wherein εaid εecond εet of conditions compriεeε increaεing the temperature under which εaid bacteria are cultured εuch that the replication of said temperature senεitive plaεmid iε εubstantially inhibited, wherein said bacteria are free of an operable activator locus of a bacterial multiple antibiotic resistance operon on a chromosome of said bacteria, and wherein said bacteria are recombination deficient. 34. A method aε in claim 32 wherein εaid firεt εet of conditionε comprises introducing within said bacteria a temperature sensitive plasmid including an operable oligonucleotide sequence encoding an mRNA transcript characterized by substantial homology to at least a portion of a repreεεor locus of a bacterial multiple antibiotic resistance operon such that said tranεcript substantially inhibits the expresεion of εaid repreεεor locuε, and wherein said second set of conditions compriseε increasing the temperature under which said bacteria are cultured such that the replication of said temperature senεitive plaεmid iε εubεtantially inhibited, wherein εaid bacteria poεεeεε an operable bacterial multiple antibiotic reεiεtance operon on a chromoεome of said bacteria, and wherein said bacteria are recombination deficient. 35. A method as in claim 32 wherein εaid εecond set of conditions compriseε expoεing εaid bacteria to a tranεpoεon such that said transposon enters εaid bacteria and inactivateε an activator locuε of a bacterial multiple antibiotic reεiεtance operon by inεertion within said locus. 36. A method as in claim 33 wherein εaid marker locuε iε a εequence encoding an enzyme. 37. A method aε in claim 36 wherein εaid marker locuε iε a εequence encoding at least a portion of a bacterial beta-galactoεidaεe. 38. A method as in claim 36 wherein εaid marker locuε iε a sequence encoding at least a portion of a bacterial alkaline phoεphataεe. 39. A method of identifying bacterial loci which affect reεistance to antibiotic compositionε compriεing subjecting bacteria to a first set of conditionε εuch that εaid bacteria do not express a multiple antibiotic resistance phenotype, introducing within said bacteria an oligonucleotide sequence including a marker locus and free of a regulatory region operably joined to said marker locus, permitting said sequence to integrate within a chromosome of said bacteria, assaying for expression of said marker locus, subjecting a subset of said bacteria which do not expresε said marker locus to a second set of conditions such that said subset of bacteria expresε said phenotype; asεaying for bacteria in said subset of bacteria which expresε εaid marker locuε under εaid second set of conditions, and determining the site of integration of εaid marker locuε in said subset of bacteria which do not expresε εaid marker locuε under said first εet of conditionε and which expreεε εaid marker locuε under εaid second εet of conditionε 40. A method aε in claim 39 wherein εaid firεt set of conditionε comprises growing said bacteria in a culture subεtantially free of inducerε of a bacterial multiple antibiotic reεiεtance operon, wherein εaid εecond εet of conditions compriεeε exposing said bacteria to an inducer of a bacterial multiple antibiotic resiεtance operon εuch that εaid inducer enterε said bacteria and induces expresεion of a multiple antibiotic resistance phenotype in said bacteria. 41. A method as in claim 40 wherein said marker locus is a sequence encoding an enzyme. 42. A method aε in claim 41 wherein εaid marker locuε iε a sequence encoding at least a portion of a bacterial beta-galactosidaεe. 43. A method aε in claim 41 wherein said marker locuε iε a sequence encoding at least a portion of a bacterial alkaline phosphatase. 44. A composition comprising an isolated oligonucleotide sequence, including at least a portion of a regulatory region of a bacterial multiple antibiotic resistance operon operably joined to a marker locus such that the expression of said marker locus is substantially dependent upon said portion, wherein said marker locus is a locus other than a bacterial multiple antibiotic resistance operon locuε. 45. The composition of claim 44 wherein said marker locus iε a εequence encoding an enzyme. 46. The compoεition of claim 45 wherein εaid marker locuε iε a sequence encoding at least a portion of a bacterial beta-galactosidaεe. 47. A compoεition comprising an isolated oligonucleotide εequence, wherein εaid εequence iε sufficiently homologous to a bacterial multiple antibiotic resistance operon so as to be capable of binding in a sequence specific manner to said operon, and wherein said εequence iε of sufficient length such that said binding distinguiεheε εaid operon from loci other than bacterial multiple antibiotic resistance operon loci. 48 . A composition compris ing a cloned oligonucleotide sequence including at least a substantial portion of a bacterial multiple antibiotic resistance operon. 49. The composition of claim 47 wherein said sequence comprises at least a portion of a represεor locuε of a bacterial multiple antibiotic reεistance operon operably joined to at least a portion of a regulatory region such that the expresεion of said repressor is substantially dependent upon said portion of a regulatory region, and said sequence is free from operable sequences encoding an activator of a bacterial multiple antibiotic resiεtance operon. 50. The compoεition of claim 47 wherein εaid sequence comprises an anti-sense locus operably joined to at least a portion of a regulatory region such that the expreεεion of εaid anti-sense locus is subεtantially dependent upon εaid portion of a regulatory region, said anti-εenεe locuε encodeε an mRNA transcript characterized by subεtantial anti-εenεe homology to at leaεt a portion of a DNA or mRNA of an activator locuε of εaid bacterial multiple antibiotic reεiεtance operon and εaid sequence is free of operable sequences encoding a represεor locuε of εaid bacterial multiple antibiotic reεiεtance operon. 51. The composition of claim 47 wherein said sequence compriseε at leaεt a portion of an activator locuε of a bacterial multiple antibiotic reεistance operon operably joined to at least a portion of a regulatory region such that the expression of said activator gene is substantially dependent upon said portion of said regulatory region and said sequence is free of operable sequences encoding a repressor of a bacterial multiple antibiotic resistance operon. 52. The composition of claim 47 wherein said sequence compriseε an anti-senεe locuε operably joined to at leaεt a portion of a regulatory region such that the expresεion of said anti-sense locus is substantially dependent upon said portion of a regulatory region, said anti-sense locus encodes an mRNA transcript characterized by substantial homology to at least a portion of a repressor locus of said bacterial multiple antibiotic resistance operon and said sequence is free of operable sequences encoding an activator of said bacterial multiple antibiotic resiεtance operon. 53. The composition of claim 51 wherein said εequence is included in a temperature sensitive plasmid. 54. The compoεition of claim 52 wherein εaid εequence iε included in a temperature sensitive plasmid. 55. An antibacterial composition compriεing an antibiotic compoεition and a εubεtance which inhibits the expreεεion of a bacterial multiple antibiotic reεiεtance operon. 56. An antibacterial compoεition aε in claim 55 wherein the εubεtance iε an oligonucleotide εequence, εaid sequence comprising at leaεt a portion of a repreεεor locuε of a bacterial multiple antibiotic resiεtance operon operably joined to at least a portion of a regulatory region such that the expression of said represεor locuε iε substantially dependent upon said portion of a regulatory region and said sequence is free from operable sequenceε encoding an activator of a bacterial multiple antibiotic reεiεtance operon. 57. An antibacterial compoεition aε in claim 55 wherein the substance is an oligonucleotide sequence characterized by substantial homology to at least a portion of an activator locus of a bacterial multiple antibiotic resistance operon such that said composition is capable of substantially inhibiting the expression of said locus. 58. An antibacterial compoεition aε in claim 55 wherein the εubεtance is an inhibitor of the activity of an activator of a bacterial multiple antibiotic resistance operon. 59. A composition comprising substantially pure represεor of a bacterial multiple antibiotic resistance operon. 60. A composition as in claim 59 wherein εaid represεor iε labeled. 61. A compoεition compriεing εubεtantially pure activator of a bacterial multiple antibiotic reεiεtance operon. 62. A compoεition aε in claim 61 wherein said activator iε labeled. 63. A compoεition compriεing εubεtantially pure oligonucleotide characterized by εubεtantial homology to at leaεt a portion of a repressor locus of a bacterial multiple antibiotic resiεtance operon wherein said oligonucleotide has sufficient homology εo as to be capable of binding in a sequence specific manner to said portion of said repressor locus, and wherein said oligonucleotide is of εufficient length such that such binding distinguisheε said portion of εaid repreεεor locuε from loci other than bacterial multiple antibiotic reεiεtance operon repressor loci. 64. A composition as in claim 63 wherein said oligonucleotide is labeled. 65. A compoεition compriεing substantially pure oligonucleotide characterized by substantial homology to at least a portion of an activator locus of a bacterial multiple antibiotic resistance operon wherein said oligonucleotide has sufficient homology so aε to be capable of binding in a sequence specific manner to said portion of said activator locus, and wherein said oligonucleotide is of εufficient length such that such binding distinguisheε said portion of said activator locuε from loci other than bacterial multiple antibiotic reεistance operon activator loci. 66. A compoεition aε in claim 65 wherein εaid oligonucleotide iε labeled. 67. Bacterial cellε into which have been introduced a compoεition εelected from the group conεiεting of the compoεition of claim 44, the composition of claim 45, the compoεition of claim 46, the composition of claim 47, the compoεition of claim 48, the compoεition of claim 49, the compoεition of claim 50, the compoεition of claim 51, and the compoεition of claim 52. 68. Bacterial cellε into which have been introduced the compoεition of claim 53. 69. Bacterial cells of claim 68 wherein said bacteria are recombination deficient. 70. Bacterial cellε of any one of claims 68 or 69 wherein said bacteria are free of an operable multiple antibiotic resiεtance operon on a chromoεome. 71. Bacterial cells into which have been introduced the compoεition of claim 54. 72. Bacterial cells of claim 71 wherein said bacteria are recombination deficient. 73. An iεolated oligonucleotide sequence comprising SEQ ID NO. 1.

Inventors: LEVY STUART B, LEVY, STUART, B.
Applicants: TUFTS COLLEGE, TRUSTEES OF TUFTS COLLEGE
Application year: 1993
Main classification: C12Q1
IPC codes: C12N15, C12Q1