bluuebunny/crossref_metadata_2025 huggingface dataset:
Protein composition of Rhodopseudomonas sphaeroides outer membrane
Authors: Baumgardner D , Deal C , Kaplan S
Published: January 2020

The outer membrane polypeptide profile of Rhodopseudmonas sphaeroides was characterized. Solubilization of the outer membrane at 75 or 100 degrees C as opposed to room temperature resulted in the dissociation of 75-, 72-, and 68-kilodalton (kdal) polypeptide aggregates into 29-, 26.5-, and 21.5-kdal polypeptides, respectively, and a shared 47-kdal subunit. Similarly, an 88.5-kdal polypeptide dissociates into a 45-kdal monomeric form, and the electrophoretic mobility of a 58.5-kdal polypeptide was altered to 83 kdal.Lysozyme treatment of outer membrane fractions altered the 21.5-kdal polypeptide mobility to 23 kdal. The presence of lipid in both the 47-kdal polypeptide and an 8- to 10-kdal polypeptide was demonstrated by lipid staining and [14C]acetate incorporation. The lipid component of the 47-kdal polypeptide was neither lipopolysaccharide nor phospholipid. The 8- to 10-kdal polypeptide may be the equivalent of the Braun lipoprotein. Outer membrane fractions isolated from R. sphaeroides-specific phage RS1-resistant mutants were deficient in several of the high-molecular-weight aggregates involving the 47-kdal polypeptide.
Genetic control of tyramine oxidase, which is involved in derepressed synthesis of arylsulfatase in Klebsiella aerogenes
Authors: Oka M , Murooka Y , Harada T
Published: January 2020

Mutants of Klebsiella aerogenes with three types of mutations affecting regulation of tyramine oxidase were isolated by a simple selection method. In the first type, the mutation (tynP) was closely linked to the structural gene for tyramine oxidase tynA). The order of mutation sites was atsA-tynP-tynA. In the second type, the mutation that relieves catabolite repression of the syntheses of several catabolite repression-sensitive enzymes are not linked to the tyn gene by P1 transduction. These strains contained high levels of cyclic adenosine 5'-monophosphate when grown on glucose. The third type of mutation, in which tyramine oxidase was synthesized constitutively, was shown by genetic analysis to involve mutations of tynP and tynR. The tynR gene was not linked to tynA. Results using the constitutive mutants showed that the constitutive expression of the tynA gene resulted in depression of arylsulfatase synthesis in the absence of tyramine.
Conservation and variation of nucleotide sequences within related bacterial genomes: Escherichia coli strains
Authors: Anilionis A , Riley M
Published: January 2020

Changes in the patterns produced by annealing restriction endonuclease digests of bacterial genomes with probe deoxyribonucleic acids (DNAs) containing small portions of a bacterial genome provide sensitive indicator of the degree of nucleotide sequence relatedness that exists in localized regions of the genomes of closely related bacteria. We have used five probe DNAs to explore the relatedness of parts of the genomes of six laboratory Escherichi coli strains. A range in in the amount of variability in the positions of restriction enzyme cleavage sites in the selected portions of the genomes was found. Portions of the genome that are believed to be inacative were more variable than portions that contained functional genes: the sites in and near regions of homology to phage lambda DNA in the genome showed the greatest variability. These regions probably represent remnants of cryptic prophages. Variability was assessed pairwise among four of the E. coli strains and ranged from 5 to > 25% base pair substitutions in the lambda-related regions. In contrast, the endonuclease cleavage sites in the trp, tna, lac, thy regions, and one other as-yet-unidentified segment of the genome were more highly conserved. It seems likely that these sites lie in genetic locations that are subject to functional constraints.
Encapsidation of yeast killer double-stranded ribonucleic acids: dependence of M on L
Authors: Bostian K A , Sturgeon J A , Tipper D J
Published: January 2020

Virus-like particles containing either L or M double-stranded ribonucleic acid (dsRNA) were isolated from a killer toxin-producing strains of Saccharomyces cerevisiae (K+ R+). At least 95% of M- and 87% of L-dsRNA were recovered in virus-like particle-containing fractions. The major capsid polypeptides (ScV-P1) of both L and M virus-like particles were shown to be identical, and 95% of the cellular ScV-P1 was found in the virus-like particle-containing fractions. Since L-dsRNA encodes ScV-P1, provision of this protein for encapsidation of M-dsRNA defines at least one functional relationship between these dsRNA genomes and associates the L-dsRNA with the killer character. If encapsidation of M-dsRNA is essential for its replication or expression, then L-dsRNA plays an essential role in maintenance or expression of the killer phenotype. The relationship between the L- and M-dsRNA genomes would be analogous to that between a helper and a defective virus. The presence of only minor quantities or uncomplexed dsRNA and ScV-P1 suggests that their production is stringently coupled.
Unit Cell Hypothesis for
Streptococcus faecalis
Authors: Edelstein Eugene M. , Rosenzweig Martin S. , Daneo-Moore Lolita , Higgins Michael L.
Published: January 2020

The mass doubling times of exponential-phase cultures of
Streptococcus faecalis
were varied from 30 to 110 min by omitting glutamine from a defined growth medium and providing different concentrations of glutamate (ranging from 300 to 14 μg/ml). After Formalin fixation, cells were dried by the critical point method, and carbon-platinum replicas were prepared. The surface area and volume of cell poles seen in these replicas were estimated by a computer-assisted, three-dimensional reconstruction technique. It was found that the amount of surface area and volume of poles seen in these replicas were independent of the growth rate of culture from which the samples were taken. These observations were consistent with the unit cell model hypothesis of Donachie and Begg, in which a small number of surface sites would produce a constant amount of new cell surface regardless of the mass doubling time of the culture. However, measurements of the thickness of the cell wall taken from thin sections of the same cells showed that the cell wall increased in thickness as a function of the increase in cellular peptidoglycan content which occurs when the growth rate of this organism is slowed down by a decrease in glutamate concentration. Thus, it would seem that although the size of polar shells made by
S. faecalis
is invariant with growth rate, the amount of wall precursors used to construct these shells is not.
Ultraviolet light induction of recA protein in a recB uvrB mutant of Escherichia coli
Authors: Bockrath R C , Hanawalt P C
Published: January 2020

Full and persistent ultraviolet light induction of recA protein with minimal bacterial deoxyribonucleic acid degradation implicates blocked replication sites rather than degradation products as the inducing signals.
Growth of Salmonella bacteriophage P22 in Escherichia coli dna(Ts) mutants
Authors: Schanda-Mulfinger U E , Schmieger H
Published: January 2020

Salmonella bacteriophage P22 grows in two deoxyribonucleic acid initiation mutants of Escherichia coli under nonpermissive conditions, dnaA and dnaC. Functional products of genes dnaE, dnaZ, lig, dnaK, and dnaG are indispensable for deoxyribonucleic acid replication of P22. In 11 E. coli dnaB mutants belonging to all phenotypic groups, phage were produced at 42 degrees C.
Continuous monitoring, by mass spectrometry, of H2 production and recycling in Rhodopseudomonas capsulata
Authors: Jouanneau Y , Kelley B C , Berlier Y , Lespinat P A , Vignais P M
Published: January 2020

Hydrogen evolution and consumption by cell and chromatophore suspensions of the photosynthetic bacterium Rhodopseudomonas capsulata was measured with a sensitive and specific mass spectrometric technique which directly monitors dissolved gases. H2 production by nitrogenase was inhibited by acetylene and restored by carbon monoxide. An H2 evolution activity coupled with HD formation and D2 uptake (H-D exchange) was unaffected by C2H2 and CO. Cultures lacking nitrogenase activity also exhibited H-D exchange activity, which was catalyzed by a membrane-bound hydrogenase present in the chromatophores of R. capsulata. A net hydrogen uptake, mediated by hydrogenase, was observed when electron acceptors such as CO2, O2, or ferricyanide were present in the medium.
Polyprenyl p-hydroxybenzoate carboxylase in flagellation of Salmonella typhimurium
Authors: Howlett B J , Bar-Tana J
Published: January 2020

Flagellation of Salmonella typhimurium was found to require a functional pathway for ubiquinone biosynthesis as well as growth in the presence of appropriate carboxylic acids. Induction of flagellation by carboxylic acids was shown to induce incorporation of p-hydroxybenzoic acid into polyprenylphenol. Constitutive flagellation was found to correlate with constitutive incorporation of p-hydroxybenzoic acid into polyprenylphenol. A novel pathway for polyprenyl p-hydroxybenzoic acid decarboxylation to polyprenylphenol was implicated in flagellation of S. typhimurium.
tif-Stimulated deoxyribonucleic acid repair in Escherichia coli K-12
Authors: Castellazzi M , Jacques M , George J
Published: January 2020

Bacterial survival is significantly increased after ultraviolet irradiation in tif sfi cells, provided that the thermosensitive tif mutation has been expressed at 41 degrees C before irradiation. This tif-mediated "reactivation of ultraviolet irradiated bacteria" needs de novo protein synthesis, as is the case for the tif-mediated reactivation of ultraviolet-irradiated phage lambda. However, in striking contrast to the phage reactivation process, this tif-mediated reactivation is no longer associated with mutagenesis. It also requires the presence of the uvrA+ excision function. These results strongly suggest the existence in Escherichia coli K-12 of a repair pathway acting on bacterial deoxyribonucleic acid which is inducible, error free, and uvr dependent.
Microcalorimetric study of Escherichia coli aerobic growth: theoretical aspects of growth on succinic acid
Authors: Dermoun Z , Belaich J P
Published: January 2020

Two methods of investigation were used to evaluate the heat quantity associated with anabolic processes (qan) during the aerobic growth of Escherichia coli in a minimal medium containing succinic acid as the sole energy and carbon source. The study of the contribution of biosynthetic reactions from succinic acid and ammonia were investigated by both methods. The two qan values obtained were in excellent agreement and were found to be significant. Thus it was demonstrated that the contribution of anabolism strongly influenced the quantity of heat associated with microbial aerobic growth. The qan calculated as above explained the experimental enthalpy change which was recently reported.
Locations of the opp and supX genes of Salmonella typhimurium and Escherichia coli
Authors: Lenny A B , Margolin P
Published: January 2020

The chromosomal locations of the supX and opp loci of Salmonella typhimurium LT2 and Escherichia coli K-12 were identified and found to result in the same gene sequence in both species, namely, pyrF-cysB-supX-trpPOLEDCBA-tonB(chr)-opp. These results differ from a previously reported location of the opp gene on the E. coli chromosome. Evidence indicates that the opp gene lies between chr(tonB) and galU in S. typhimurium.
Effect of ssbA1 and lexC113 mutations on lambda prophage induction, bacteriophage growth, and cell survival
Authors: Vales L D , Chase J W , Murphy J B
Published: January 2020

Escherichia coli strains containing mutations (ssbA1 and lexC113) which affect single-strand deoxyribonucleic acid binding protein have been examined. Among the properties studied were: sensitivity to ultraviolet irradiation and methyl methane sulfonate, temperature sensitivity, induction of prophage lambda by ultraviolet light, temperature, and mitomycin C, and deoxyribonucleic acid synthesis. Strains containing the ssbA1 and lexC113 mutations differ significantly in several of these properties.
Approach to Recognition of Regulatory Mutants of Cyanobacteria
Authors: Hall Geraldine , Flick Maryann B. , Jensen Roy A.
Published: January 2020

Antimetabolite analogs of essential amino acids are useful as selective agents for isolation of regulatory mutants of cyanobacteria, although we observed striking microbiological differences from other widely used eubacterial systems. Regulatory mutants shown to overproduce and excrete tryptophan, phenylalanine, tyrosine, methionine, or arginine were isolated from four cyanobacteria:
Anabaena
sp. 29151,
Synechococcus
sp. 602,
Synechococcus
sp. AN Tx20, and
Synechocystis
sp. 29108. Surprisingly, regulatory-mutant colonies did not support a halo of cross-fed wild-type growth on selective medium. Since regulatory mutants were shown to excrete substantial levels of amino acids, it was deduced that poor cross-feeding must reflect a generally low nutritional responsiveness of the cyanobacterial background. This conclusion was confirmed by results which showed that regulatory-mutant cells of cyanobacteria dispersed among wild-type populations of
Bacillus subtilis
did produce halo colonies on solid analog-containing medium. Cross-feeding between one cyanobacterial pair (a phenylalanine excretor and a phenylalanine auxotroph) was successfully demonstrated in the absence of the analog under conditions in which relatively large masses of each cell population type were spread near one another on agar plates. These results suggest that amino acid excreted by regulatory mutants of cyanobacteria on analog-containing selective medium is transported into nearby wild-type cells too inefficiently to overcome the antimetabolite effects of the analog, thereby failing to generate halos of physiologically resistant background cells. Consistent with this interpretation was the finding that the
pheA1
auxotroph from
Synechococcus
sp. 602 exhibited a linearly proportional dependence of growth rate upon exogenous concentration of
l
-phenylalanine (below 20 μM). Wild-type
B. subtilis
serves as a convenient and sensitive test lawn for screening obvious regulatory mutants from among collections of analog-resistant cyanobacterial mutants. Appropriate
B. subtilis
auxotrophs can be used as convenient indicator strains for the identification of regulatory mutants in cyanobacteria through the observation of syntrophic growth responses.
Treponema innocens lipids and further description of an unusual galactolipid of Treponema hyodysenteriae
Authors: Matthews H M , Yang T K , Jenkin H M
Published: January 2020

The lipids of Treponema innocens, type strain B256, formerly considered a nonpathogenic isolate of T. hyodysenteriae, have been analyzed and compared with the lipids of T. hyodysenteriae. The lipids of T. innocens comprised 16% of the cell dry weight. Polar lipids amounted to about two-thirds of the total lipids and consisted of 61.9% phospholipids and 38.1% glycolipid. Neutral lipids consisted mainly of sterols. The phospholipids were principally phosphatidylglycerol, phosphatidylcholine, and cardiolipin. Minor amounts of lysophosphatidylcholine, sphingomoyelin, and a relatively nonpolar, unidentified phospholipid were present. The latter lipid has not been detected in T. hyodysenteriae. The glycolipid fraction of T. innocens contained a single component, monoglucosyldiglyceride, in contrast to the occurrence in T. hyodysenteriae of two components: monogallactosyldiglyceride and a less-polar glycolipid tentatively identified as acylmonogalactosyldiglyceride (the additional acyl moieties being 86.6% acetyl, 11.6% propionyl, and 1.6% n-butyryl groups). Alk-1-enyl ether analogs comprised 24.6% of the total phospholipids and glycolipid of T. innocens, or about one-third of the amount in T. hyodysenteriae. The acyl and alk-1-enyl moieties of T. innocens consisted of greater than or equal to 92% of 14:0, iso-15:0, and 16:0 chains. In contrast to T. hyodysenteriae, anteiso-15:0 moieties were not detected, and a reversed distribution of 14:0 and iso-15:0 alk-1-enyl moieties occurred in the two species.
Tn2301, a transposon construct carrying the entire transfer region of the F plasmid
Authors: Johnson D A , Willetts N S
Published: January 2020

The largest R . BamHI fragment of the plasmid F, which carries the entire F conjugation system, has been cloned into the single R . BamHI site of the ampicillin (Ap) resistance transposon TN1. pDS1106 (ColE1 mob::Tn1) was the vector plasmid, and the resultant conjugative plasmid, pED830, was characterized both genetically and by restriction enzyme analysis. The transposon construct, denoted Tn2301, was transposable at frequencies similar to Tn1 to small nonconjugative plasmids or to the Escherichia coli host chromosome. In the former case, Apr conjugative plasmids were obtained, whereas in the latter case, Hfr strains resulted. Representative Hfr strains were characterized by quantitative and interrupted mating experiments. Extension of this technique for Hfvr formation should aid chromosome mapping both in E. coli and in other bacterial genera.
Genetic analysis of Saccharomyces cerevisiae transformed by plasmid containing a supressor transfer ribonucleic acid gene
Authors: Thomas D Y , James A P
Published: January 2020

The behavior in Saccharomyces cerevisiae of plasmid pYTE1, which contains yeast tyrosine-inserting ochre suppressor SUP4.o, a 4-kilobase EcoRI fragment of yeast 2muDNA, and the bacterial plasmid pBR322, has been studied. Selection of yeast transformants was by suppression of multiple ochre mutations. About 10(3) to 10(4) transformants per microgram of pYTE1 dfeoxyribonucleic acid were obtained. The majority of transformants contained both an integrated copy of the SUP4.o gene plus pBR322 deoxyribonucleic acid sequences and autonomously replicating forms of the plasmid. The integrated copy was extremely stable mitotically and meiotically, but the associated nonintegrated copies were lost at meiosis. The chromosomally integrated pBR322 sequences were linked to the SUP4.o gene. The integration site was at the SUP4+ locus. In transformants with only nonintegrated copies of pYTE1, the expression of suppression was reduced, and the plasmid was unstable in mitosis. Plasmid deoxyribonucleic acid preparations from both types of transformant could be used to retransform yeast cells. Plasmid pYTE1 has restriction enzyme sites useful for the high frequency and stable transformation of other genes into yeasts. The potential uses of this plasmid for transformation of other organisms is discussed.
Pattern of ribonucleic acid synthesis during germination of Allomyces macrogynus mitospores
Authors: Smith B A , Burke D D
Published: January 2020

The relationship between ribonucleic acid (RNA) synthesis and germination of Allomyces macrogynus mitospores was investigated. It was determined that the synthesis of all classes of RNA was initiated during the first 10 min of germination, around the time of encystment. It is during this stage that the membrane of the nuclear cap structure begins to break down, dispersing the cell complement of ribosomes throughout the cytoplasm. After encystment, there was an increase in the rate of synthesis of the four stable RNA species (4S, 5S, 19S, and 27S) which leveled off as the germ tube emerged. Data suggested that messenger RNA was synthesized at an increasing rate during the course of germination. Studies of RNA precursor pool behavior and RNA synthesis in the presence and absence of actinomycin D indicated that no species of RNA, including messenger RNA, was synthesized in the presence of actinomycin D. Further, precursor pool measurement indicated that the apparent increase in the rate of RNA synthesis during germination was largely due to increased specific activity of the RNA precursor pool.
Genetic organization of the broad-host-range IncP-1 plasmid R751
Authors: Meyer R J , Shapiro J A
Published: January 2020

We have identified regions encoding conjugal transfer, plasmid maintenance, and trimethoprim resistance on the IncP-1 plasmid R751 by complementation tests with cloned deoxyribonucleic acid fragments and self-replicating derivatives constructed in vitro. The genes for replication and transfer show a scattered organization similar to that previously determined for RK2, another IncP-1 plasmid. Derivatives of RK2 are able to complement R751 derivatives defective in these functions. Restriction enzyme cleavage sites in R751 deoxyribonucleic acid are clustered in regions of the plasmid physical map. Neither region is required for plasmid maintenance or transfer, although one determines resistance to trimethoprim. A similar clustering of cleavage sites is seen with RK2, which nevertheless has a very different restriction map.
recA gene product is responsible for inhibition of deoxyribonucleic acid synthesis after ultraviolet irradiation
Authors: Trgovcević Z , Petranović D , Petranović M , Salaj-Smic E
Published: January 2020

Deoxyribonucleic acid synthesis after ultraviolet irradiation was studied in wild-type, uvrA, recB, recA recB, and recA Escherichia coli strains. Inhibition of deoxyribonucleic acid synthesis, which occurs almost immediately after exposing the cells to ultraviolet radiation, depends on the functional gene recA.
Hydrogenase activity in Rhodopseudomonas capsulata: relationship with nitrogenase activity
Authors: Colbeau A , Kelley B C , Vignais P M
Published: January 2020

Hydrogenase activity was found in cells of Rhodopseudomonas capsulata strain B10 cultured under a variety of growth conditions either anaerobically in the light or aerobically in the dark. The highest activities were found routinely in cells grown in the presence of H2. The hydrogenase of R. capsulata was localized in the particulate fraction of the cells. High hydrogenase activities were usually observed in cells possessing an active nitrogenase. The hydrogen produced by the nitrogenase stimulated the activity of hydrogenase in growing cells. However, the synthesis of hydrogenase was not closely linked to the synthesis of nitrogenase. Hydrogenase was present in dark-grown cultures, whereas nitrogenase synthesis was not significant in the absence of light. Unlike nitrogenase, hydrogenase was present in cultures grown on NH4+. Conditions were established which allowed the synthesis of either nitrogenase or hydrogenase by resting cells. We concluded that hydrogenase can be synthesized independently of nitrogenase.
Biochemical and immunological characterization of an R plasmid-encoded protein with properties resembling those of major cellular outer membrane proteins
Authors: Ferrazza D , Levy S B
Published: January 2020

MRB, a major R222 plasmid-encoded protein previously described by us, is synthesized in large amounts in host Escherichia coli cells, where it is located principally in the outer membrane. Most of this protein is also bound to the peptidoglycan layer in a form which is trypsin resistant. Its monomeric molecular weight is about 29,000, but it is isolated from cell membranes in aggregate molecular weights of more than 100,000. These properties demonstrate a strong similarity between MRB and porins, major outer membrane proteins of host E. coli cells. They suggest that MRB may have an as-yet unidentified transport function, as do cellular outer membrane proteins with similar biochemical properties. By using antiserum specific for MRB, we demonstrated identity between MRB and the product of the traT gene, one of the surface exclusion proteins on the F plasmid. The synthesis of MRB was found to be constitutive, in contrast to other tra genes, which appear to be under more rigid regulation by the tra operon. These findings suggest that on R222 and other F-like R plasmids this protein has its own promoter.
Salmonella typhimurium mutants with reduced levels of transfer ribonucleic acid-inhibitable endodeoxyribonucleolytic activity
Authors: Zabel D J , Trucksis M , Depew R E
Published: January 2020

Two methods of mutagenesis, chemical alkylation and insertion of the tetracycline resistance transposon Tn10, were used to generate mutants of Salmonella typhimurium which had reduced levels of endodeoxyribonucleolytic activity. The chemically induced mutations defined a locus, endA, which was cotransduced with serA at a low frequency and with metK at a high frequency. Three-factor crosses revealed that metK was between serA and endA. The major endodeoxyribonucleolytic activity in crude extracts of s. typhimurium was similar to the activity of Escherichia coli endonuclease I. A Tn10 insertion mutation of endA resulted in the most severe loss of endodeoxyribonucleolytic activity among the endA alleles studied. Two of the chemically induced mutations resulted in activities which were more thermolabile than the wild-type activity.
Regulation of ilvEDA expression occurs upstream of ilvG in Escherichia coli: additional evidence for an ilvGEDA operon
Authors: Subrahmanyam C S , Noti J D , Umbarger H E
Published: January 2020

A low-copy-number plasmid was prepared that contained the entire ilv gene cluster of Escherichia coli. The introduction of an ilvO mutation allowed the ilvG gene of the plasmid to be expressed and imparted valine resistance to strains carrying it. Insertion of Tn10 into the ilvG gene of the plasmid resulted in a strong polar effect on ilv genes E, D, and A. Replacement of a region of ilv deoxyribonucleic acid between two KpnI sites on the high-copy-number plasmid carrying the entire ilv gene cluster with a KpnI fragment carrying an ilv-lac fusion but not extending into the ilv-specific control region resulted in a plasmid expressing the lacZ gene under ilv control when the fusion had been inserted in its normal orientation but not when it had been inserted in the opposite orientation. These experiments indicate that ilv-specific control over ilvE, ilvD, and ilvA expression is dependent on these genes being continguous with deoxyribonucleic acid that lies upstream of ilvG. The results also add further support to the concept of an ilvGEDA operon in E. coli.
In vitro formation of beta-galactosidase with a template containing the lac genes fused to gene ilvD
Authors: Noti J D , Umbarger H E
Published: January 2020

An in vitro coupled transcription-translation system was used to synthesize transaminase B and beta-galactosidase in the presence of a deoxyribonucleic acid template containing lac deoxyribonucleic acid under normal lac-specific control and in the presence of several deoxyribonucleic acid templates containing lac deoxyribonucleic acid fused to the ilvD gene. Time course experiments revealed that transcription of the lacZ gene from the fusion template required a longer time than did that initiated at the lac promoter. With a phage template containing an intact ilvE gene but lacking the normal ilv-specific promoter, synthesis of ilvE message was completed before synthesis of lacZ message. A phage template that contained the normal ilv-specific promoter but from which part of ilvE had been deleted also allowed formation of beta-galactosidase. Three plasmids containing the ilv-lac fusion were also used as templates. Two plasmids that contained both an intact ilvE gene and the normal ilv-specific promoter required longer times for lacZ transcription but were more efficient templates than was a plasmid in which the ilv-lac fusion, the ilvE gene, and the contiguous non-specific ilvE promoter were inverted with respect to the normal ilv-specific promoter. beta-Galactosidase synthesis was stimulated by guanosine 3'-pyrophosphate-5'-pyrophosphate with all templates tested except that in which the ilv-lac fusion had been inverted. Presumptive evidence was obtained for the generation of a limiting isoleucine signal by incorporating inhibitors of isoleucyl transfer ribonucleic acid synthetase into the coupled transcription-translation system.
Identification of a second tetracycline-inducible polypeptide encoded by Tn10
Authors: Zupancic T J , King S R , Pogue-Geile K L , Jaskunas S R
Published: January 2020

Three Tn10 polypeptides were detected by analyzing the proteins synthesized in ultraviolet light-irradiated Escherichia coli cells after infection with lambda::Tn10. One of these polypeptides was the previously identified 36,000-dalton TET polypeptide. The other two had approximate sizes of 25,000 and 13,000 daltons. The syntheses of both the TET polypeptide and the 25,000-dalton polypeptide were inducible by tetracycline in lambda-immune hosts. Similarly, the synthesis of the TET polypeptide was inducible in nonimmune hosts. However, the synthesis of the 25,000-dalton polypeptide was constitutive in nonimmune hosts. An amber mutation in a gene required for tetracycline resistance on lambda::Tn10 was isolated that eliminated the synthesis of the TET polypeptide in sup+ hosts but not the synthesis of the 25,000-dalton or the 13,000-dalton polypeptides. The expression of tetracycline resistance from wild-type Tn10 was found to be anomalous in E. coli strains carrying the amber suppressors supD, supE, and supF. In general, strains containing these nonsense suppressors were less resistant to tetracycline.
Genetic and biochemical studies of transport systems for branched-chain amino acids in Escherichia coli K-12: isolation and properties of mutants defective in leucine-repressible transport activities
Authors: Yamato I , Anraku Y
Published: January 2020

The characteristics of a mutant (hrbA) of Escherichia coli K-12 that is defective in a leucine-nonrepressible transport system, the LIV-3 system, for branched-chain amino acids were described previously (I. Yamato et al., J. Bacteriol 138:24-32, 1979). New mutants requiring a high concentration of isoleucine for growth were isolated from strain B763 (hrbA ileA) after mutagenesis with ethyl methane sulfonate. These mutants had a defect of the leucine-repressible transport activities for branched-chain amino acids of the parental strain. One of these mutants, strain B7634, had defects of two independent genetic loci (hrbBC and hrbD). The genes hrbBC were mapped at min 76 near malT, and the gene hrbD mapped at min 77 near xyl on the E. coli genetic map. The substrate specificity, kinetic properties, and source of coupling energy of the transport system coded for by each of these genes were studied using cytoplasmic membrane vesicles and intact cells. The results identified three transport systems with characteristic features other than the LIV-3 system. The hrbB and hrbC systems are responsible for the uptake activites of the LIV-2 system, with a high Km value, and the LIV-1 system, with a low Km value, respectively. Both activities are repressed by leucine and inhibited by threonine and the b(--) isomer of 2-aminobicycloheptyl-2-carboxylic acid. They both utilize adenosine 5'-triphosphate as coupling energy and are not detected in cytoplasmic membrane vesicles. The hrbD system is responsible for the LIV-4 system, with a high Km value. Its activity is repressed by leucine and partially inhibited by threonine. It is detected in cytoplasmic membrane vesicles with a proton motive force as the driving energy.
Effect of restrictive temperature on cell wall synthesis in a temperature-sensitive mutant of Bacillus stearothermophilus
Authors: Mulks M H , Souza K A , Boylen C W
Published: January 2020

A temperature-sensitive mutant of Bacillus stearothermophilus, TS-13, was unable to grow above 58 degrees C, compared to 72 degrees C for the wild type. Actively growing TS-13 cells lysed within 2 h when exposed to a restrictive temperature of 65 degrees C. Peptidoglycan synthesis stopped within 10 to 15 min postshift before a shut down of other macromolecular syntheses. Composition of preexisting peptidoglycan was not altered, nor was new peptidoglycan of aberrant composition formed. No significant difference in autolysin activity was observed between the mutant and the wild type at 65 degrees C. Protoplasts of TS-13 cells were able to synthesize cell wall material at 52 degress C, but not at 65 degrees C. This wall material remained closely associated with the cell membrane at the outer surface of the protoplasts, forming small, globular, membrane-bound structures which could be visualized by electron microscopy. These structures reacted with fluorescent antibody prepared against purified cell walls. Production of this membrane-associated wall material could be blocked by bacitracin, which inhibited cell wall synthesis at the level of transport through the membrane. The data were in agreement with previous studies showing that at the restrictive temperature this mutant is unable to alter its membrane fatty acid and phospholipid composition with temperature such that it is not able to maintain a membrane lipid composition which permits normal membrane function at the restrictive temperature.
Comparison of the polypeptide composition of Escherichia coli outer membranes prepared by two methods
Authors: Chopra I , Shales S W
Published: January 2020

Escherichia coli outer membranes were prepared by centrifugation to equilibrium in sucrose gradients and then treated with Sarkosyl in the presence of ethylenediaminetetraacetate. The polypeptide profiles of the two outer membrane preparations were compared by two-dimensional polyacrylamide gel electrophoresis. The patterns obtained were not identical, and Sarkosyl removed several minor proteins from the outer membrane.
Incorporation of acyl moieties of phospholipids into murein lipoprotein in intact cells of Escherichia coli by phospholipid vesicle fusion
Authors: Lai J S , Wu H C
Published: January 2020

The biosynthesis of the acyl moieties in murein lipoprotein was studied by fusion of [3H]palmitate-labeled phospholipid vesicles with intact cells of an fadD mutant of Escherichia coli. A linear increase in the incorporation of [3H]palmitate radioactivity into both the ester- and amide-linked fatty acids in lipoprotein was observed during a 3-h chase after the fusion. Addition of chloramphenicol completely prevented the incorporation of [3H]palmitate from phospholipids to lipoprotein. These results strongly support our hypothesis that the acyl moieties in phospholipids are the precursors for the fatty acids in murein lipoprotein of E. coli. Among the major glycerophosphatides in E. coli, no specificity was observed regarding the efficacy of the donor.
Genome size of the rickettsia Coxiella burnetii
Authors: Myers W F , Baca O G , Wisseman C L
Published: January 2020

The genome size of Coxiella burnetii Nine Mile strain was determined by the method of initial rate of deoxyribonucleic acid renaturation. The mean value obtained was 1.04 X 10(9) daltons.
Methyl-alpha-maltoside and 5-thiomaltose: analogs transported by the Escherichia coli maltose transport system
Authors: Ferenci T
Published: January 2020

Neither methyl-alpha-maltoside nor 5-thiomaltose is utilized by Escherichia coli as a sole carbon source. Both are, however, effective competitive inhibitors of maltose transport into the bacterium (Km for maltose, 0.8 microM, Ki for methyl-alpha-maltoside, 5.5 microM; Ki for 5-thiomaltose, 0.2 microM). Both analogs are bound by the periplasmic maltose-binding protein. Methyl-alpha-[14C]maltoside and 5-[3H]thiomaltose were both accumulated inside E. coli. Methyl-alpha-maltoside was unchanged after accumulation, but 5-thiomaltose was converted to an unidentified compound that could exit from the bacterium. Both analogs were inhibitory to the growth of E. coli, but only when the bacteria were previously induced for the maltose transport system. The analogs are substrates for but poor inducers of the maltose transport system.
Bacillus megaterium sporal peptidoglycan synthesis studied by high-resolution autoradiography
Authors: Frehel C , Ryter A
Published: January 2020

Cells of a Dap- Lys- mutant strain of Bacillus megaterium were pulse labeled with [3H]diaminopimelic acid at different times of growth and sporulation. They were processed for radioactivity measurements and high-resolution autoradiography either just after the pulse or after a chase in a nonradioactive medium until refractile forespores started to appear at time (t)4,5. In the pulse-labeled cells, autoradiographs and radioactivity measurements showed that the radioactivity incorporated during a pulse decreased abruptly after t0 and stayed at a low level until t5, although the forespore wall and cortex were formed between t4 and t5. In the pulse-chased bacteria, the acid-insoluble radioactivity, as well as the number of silver grains on autoradiographs, increased during the chase in cells labeled at t1 to t2, whereas it decreased in those labeled before t0. Furthermore, analysis of silver grain distribution showed that, in stage IV bacteria, grains were distributed at the outside of the forespore, mostly on the sporangium cell wall, when pulse-labeling occurred before or at t0; they were located along the cortex and in the forespore cytoplasm when labeling was made at t1 or t2. These facts show that [3H]diaminopimelic acid necessary for spore envelope synthesis was incorporated before their morphological appearance. Free or small diaminopimelic acid precursors entered the sporangium between t1 and t2. The appearance of silver grains in the forespore cytoplasm suggests that the forespore is implicated in sporal peptidoglycan synthesis.
Induction of arginase and ornithine transaminase in the fission yeast Schizosaccharomyces pombe
Authors: Benítez T , Farrar L
Published: January 2020

The induction of arginase and ornithine transaminase in the fission yeast Schizosaccharomyces pombe requires the absence of ammonia and the presence of the inducer arginine. It seems that immediate arginase degradation is initiated by starved cells or ones from which arginine has been removed.
Protein identifications on O'Farrell two-dimensional gels: locations of 55 additional Escherichia coli proteins
Authors: Phillips T A , Bloch P L , Neidhardt F C
Published: January 2020

The resolution of proteins from whole-cell homogenates by two-dimensional gel electrophoresis is sufficiently reproducible and precise to permit different laboratories to exchange information about them. To the previous total of 81 we add the locations of 55 Escherichia coli proteins determined with the aid of purified proteins and mutant strains supplied by many investigators. The criteria used to establish the identifications of protein spots include migration with marker proteins, altered position or amount in appropriate mutant or plasmid-carrying strains, physiological behavior, and peptide map pattern.
Deletion of the penicillin-binding protein 5 gene of Escherichia coli
Authors: Spratt B G
Published: January 2020

A strain of Escherichia coli that has a deletion of the entire dacA gene has been constructed. The complete lack of penicillin-binding protein 5 in this strain establishes that the activity of this protein is not essential for the growth of E. coli.
Regulation of the cellulolytic system in Trichoderma reesei by sophorose: induction of cellulase and repression of beta-glucosidase
Authors: Sternberg D , Mandels G R
Published: January 2020

Sophorose has two regulatory roles in the production of cellulase enzymes in Trichoderma reesei: beta-glucosidase repression and cellulase induction. Sophorose also is hydrolyzed by the mycelial-associated beta-glucosidase. Repression of beta-glucosidase reduces sophorose hydrolysis and thus may increase cellulase induction.
Suppression of polarity in the gal operon by ultraviolet irradiation
Authors: Fassler J S , Tessman I
Published: January 2020

The polarity of nonsense mutations in the galE gene of Escherichia coli can be suppressed by rho mutations (O. Reyes et al., J. Bacteriol. 126:1108-1112, 1976). We show here that this polarity can also be suppressed by ultraviolet irradiation. The effect is analogous to that already observed for polar nonsense mutations in phi X174 and S13 and suggests that ultraviolet irradiation suppression of polarity may be a general phenomenon.
Methylation patterns of mycoplasma transfer and ribosomal ribonucleic acid
Authors: Hsuchen C C , Dubin D T
Published: January 2020

The methylation patterns of transfer and ribosomal ribonucleic acid (RNA) from two mycoplasmas, Mycoplasma capricolum and Acholeplasma laidlawii, have been examined. The transfer RNA from the two mycoplasmas resembled that of other procaryotes in degree of methylation and general diversity of methylated nucleotides, and bore particular resemblance to Bacillus subtilis transfer RNA. The only unusual feature was the absence of m5U from M. capricolum transfer RNA. The methylation patterns of the mycoplasma 16S RNAs were also typically procaryotic, retaining the methylated residues previously shown to be highly conserved among eubacterial 16S RNAs. The mycoplasma 23S RNA methylation patterns were, on the other hand, quite unusual. M. capricolum 23S RNA contained only four methylated residues in stoichiometric amounts, all of which were ribose methylated. A. laidlawii 23S RNA contained the same ribose-methylated residues, plus in addition approximately six m5U residues. These findings are discussed in relation to the phylogenetic status of mycoplasma, as well as the possible role of RNA methylation.
Molecular cloning of Escherichia coli K-12 hexuronate system genes: exu region
Authors: Ritzenthaler P , Mata-Gilsinger M , Stoeber F
Published: January 2020

Lambda transducing bacteriophages carrying the exu region (min 66) of Escherichia coli K-12 (lambda pexu) were previously isolated. A restriction map of these phages is presented. Starting from the lambda pexu phage deoxyribonucleic acid, various endonuclease-generated exu fragments were subcloned into multicopy plasmid vectors, using in vitro recombination techniques. The precise location of the exu genes, relative to the endonuclease sites, was determined. Plasmids carrying uxaC and uxaA genes overproduced the corresponding enzymes 30- to 40-fold. When these plasmids were expressed in an in vitro protein-synthesizing system, two polypeptides of 50,500 and 53,000 molecular weights appeared and were identified as the uxaC and uxaA gene products. A 2.6-kilobase-pair deoxyribonucleic acid fragment was shown to code for a functional exuR repressor which controls the expression of the exu region. Plasmids containing this fragment overproduced the regulatory protein. It was possible to localize the operator region, uxaCo, which overlapped a PstI endonuclease site, and to confirm the transcriptional direction of the uxaC-uxaA operon from uxaC to uxaA.
Biological consequences of infection of Escherichia coli B by alkylated T7 bacteriophage
Authors: Karska-Wysocki B , Mamet-Bratley M D
Published: January 2020

Alkylation of T7 bacteriophage considerably delayed phage development and reduced the phage's killing action on host cells. Only a small fraction of infected cells produced phage. For these phages, the latent period was markedly prolonged but the burst was equivalent to or only slightly lower than that of untreated phage. In the progeny of alkylated phage, there was an increase in the fraction of defective particles as well as a change in their morphology. These data show that infection with alkylated T7 bacteriophage is to a large degree abortive; hence, biological consequences of this infection are very different from those characteristic of a normal virus infection.
Mechanism of the rel defect in beta-galactosidase synthesis
Authors: Foley D , Dennis P , Gallant J
Published: January 2020

Relaxed (relA) mutants of Escherichia coli are defective in beta-galactosidase synthesis during amino acid limitation. We show here that this defect comprises both a transcriptional component and a translational component.
Transposition of the oxacillin-hydrolyzing penicillinase gene
Authors: Yamamoto T , Tanaka M , Nohara C , Fukunaga Y , Yamagishi S
Published: January 2020

We have found that the oxacillin-hydrolyzing penicillinase gene (oxa) encoded by plasmid RGN238 transposes to various plasmids in a recA background. We call this transposable element Tn2603. Tn2603 encodes the genes for streptomycin, sulfonamide, and mercury resistance in addition to the oxa gene. Tn2603 has a molecular size of 19.6 kilobase pairs and appears to be flanked by small inverted repeat sequences of about 200 base pairs long.
Isolation and analysis of multicopy extragenic suppressors of dnaA mutations
Authors: Projan S J , Wechsler J A
Published: January 2020

Recombinant plasmids were constructed from restriction enzyme digests of Escherichia coli chromosomal deoxyribonucleic acid and pMB9 plasmid deoxyribonucleic acid and selected for correction of the dnaA phenotype. The three plasmids isolated, all retransformed dnaA cells, both recA+ and recA, such that all tetracycline-resistant transformants selected at permissive temperature simultaneously became temperature resistant. Restriction enzyme mapping of the plasmids showed all three to be different, and it was subsequently shown that none contained the dnaA+ gene. Though each of the three plasmids suppressed three different temperature-sensitive dnaA alleles, none corrected the phenotype of an unsuppressed dnaA amber allele. It was concluded, therefore, that each plasmid contained a unique extragenic suppressor of dnaA and that the suppression was observed because of the elevated gene dosage of the cloned material. The plasmids were unstable in the absence of selection.
Lactoperoxidase-125I localization of salt-extractable alkaline phosphatase on the cytoplasmic membrane of Bacillus licheniformis
Authors: Spencer D B , Hulett F M
Published: January 2020

Previous histochemical and biochemical localizations of alkaline phosphatase in Bacillus licheniformis MC14 have shown that the membrane-associated form of the enzyme is located on the inner surface of the cytoplasmic membrane, and soluble forms are located in the periplasmic space and in the growth medium. The distribution of salt-extractable alkaline phosphatase on the surfaces of the cytoplasmic membrane of B. licheniformis MC14 was determined by using lactoperoxidase-125I labeling techniques. Cells harvested during rapid alkaline phosphatase production were converted to protoplasts or lysed protoplasts and labeled. Analysis of the data obtained indicated that 30% of the salt-extractable, membrane-associated alkaline phosphatase was located on the outer surface of the cytoplasmic membrane, whereas 70% of the membrane-associated enzyme was localized on the inner surface. Controls for protoplast integrity (release of tritiated thymidine or examination of cytoplasmic proteins for label content) indicated excellent protoplast stability. Controls indicated that chemical labeling was not a factor in the apparent distribution of alkaline phosphatase on the membrane. These results support the previously reported histochemical localization of alkaline phosphatase on the membrane inner surface. The presence of alkaline phosphatase on the membrane outer surface is reasonable, considering the soluble forms of the enzyme found in the periplasmic region and in the culture medium.
Purification of polypeptide P6 with a molecular weight of 6,000 from the vegetative chromosomes of Bacillus subtilis
Authors: Nakayama T , Kurogi Y , Irikura M
Published: January 2020

Folded chromosomes were prepared as membrane-associated complexes from vegetative cells of Bacillus subtilis by stepwise sucrose gradient centrifugation. From nucleoids, a deoxyribonucleic acid-bound polypeptide with a molecular weight of 6,000 (P6) was purified by KCl-(NH4)2SO4 salting out, diethylaminoethyl cellulose column chromatography, and deoxyribonucleic acid cellulose column chromatography. The amino acid composition of polypeptide P6 was determined.