bluuebunny/crossref_metadata_2025 huggingface dataset:
Outer membrane proteins and cell surface structure of Selenomonas ruminantium
Authors: Kamio Y , Takahashi H
Published: January 2020

The protein compositions of the membrane preparations from Selenomonas ruminantium grown in glucose or lactate medium were determined by sodium dodecyl sulfate- and two-dimensional (first, isoelectric focusing; second, sodium dodecyl sulfate) polyacrylamide slab gel electrophoresis. The outer membrane from both glucose- and lactate-grown cells contained two major proteins with apparent molecular weights of 42,000 and 40,000. These proteins existed as peptidoglycan-associated proteins in the outer membrane. The critical temperature at which they were dissociated completely into the monomeric subunits of 42,000 and 40,000 daltons was found to be 85 degrees C. The amount of each protein varied considerably depending upon the cultural conditions. The absence of the lipoprotein of Braun in S. ruminantium was suggested in our preceding paper (Y. Kamio, and H. Takahashi, J. Bacteriol. 141:888--898, 1980), and the possible absence of the protein components corresponding to the Braun lipoprotein in this strain was confirmed by electrophoretic analysis of the outer membrane and the lysozyme-treated peptidoglycan fractions. Examination of the cell surface of S. ruminantium by electron microscopy showed that the outer membrane formed a wrinkled surface with irregular blebs, some of which pinched off forming vesicles of various sizes. Rapid cell lysis occurred with the addition of a low level of lysozyme to the cell suspension. These findings led us to conclude that the physiological and morphological properties of this strain were similar to those of "deep rough" and mlp or lpo mutants of Escherichia coli K-12, respectively.
Structure of Methylosinus trichosporium exospores
Authors: Reed W M , Titus J A , Dugan P R , Pfister R M
Published: January 2020

Methylosinus trichosporium exospores did not display a well-defined cortex or an exosporium. A thick, electron-dense exospore wall was characteristic of the exospores. Located on the exterior of the exospore wall was a cell wall to which a well-defined capsule was attached. An extensive lamellar intracytoplasmic membrane system characteristic of the kind in vegetative cells of this bacterium was present along the interior periphery of the exospore wall. Upon germination of M. trichosporium exospores, the thick exospore wall gradually disappeared and a germ tube formed. The intracytoplasmic membranes of the exospores extended into the germ tube which did not possess the extensive fibrillar capsule observed on the dormant exospore. Cup-shaped exospores which have an ultrastructure similar to that of mature exospores except that they are invaginated also germinated upon exposure to methane.
Melibiose transport of Escherichia coli
Authors: Tanaka K , Niiya S , Tsuchiya T
Published: January 2020

Transport of [3H]melibiose, prepared from [3H]raffinose, was investigated in Escherichia coli. Na+ stimulated the transport of melibiose via the melibiose system, whereas Li+ inhibited it. Kinetic parameters of melibiose transport were determined. The Kt values were 0.57 mM in the absence of Na+ or Li+, 0.27 mM in the presence of 10 mM NaCl, and 0.29 mM in the presence of 10 mM LiCl. The Vmax values were 40 and 46 nmol/min per mg of protein in the absence and in the presence of NaCl and 18 nmol/min per mg of protein in the presence of LiCl. Melibiose transport via the melibiose system was temperature sensitive in a wild-type strain of Escherichia coli and was not inhibited by lactose. On the other hand, melibiose uptake via the lactose system was not temperature sensitive, was inhibited by lactose, and was not affected by Na+ and Li+. Methyl-beta-D-thiogalactoside, a substrate for both systems, inhibited the transport of melibiose via both systems.
Biochemistry and regulation of a second L-proline transport system in Salmonella typhimurium
Authors: Anderson R R , Menzel R , Wood J M
Published: January 2020

This paper reports some biochemical characteristics of a second L-proline transport system in Salmonella typhimurium. In the accompanying paper, R. Menzel and J. Roth (J. Bacteriol. 141:1064--1070, 1980) have identified this system by showing that it is inactivated by mutations at the locus proP. We have found that it is an active transport system with an apparent Km for L-proline of 3 x 10(-4) M and a strict specificity for L-proline and some of its analogs. Unlike the L-proline transport system encoded in putP, this second system is induced by amino acid limitation.
Effects of fatty acids on lysis of Streptococcus faecalis
Authors: Carson D D , Daneo-Moore L
Published: January 2020

Palmitic, stearic, oleic, and linoleic acids at concentrations of 200 nmol/ml all inhibited autolysin activity 80% or more in whole cells or cell-free extracts. This concentration of the saturated fatty acids palmitic acid and stearic acid had little or no effect on the growth of whole cells or protoplasts. However, the unsaturated fatty acids oleic acid and linoleic acid induced lysis in both situations. This lytic effect is apparently not related to any uncoupling activity or inhibition of energy catabolism by unsaturated fatty acids. It is concluded that unsaturated fatty acids induce cell and protoplast lysis by acting as more potent membrane destabilizers than saturated fatty acids.
Cotranslational secretion of diphtheria toxin and alkaline phosphatase in vitro: involvement of membrane protein(s)
Authors: Smith W P
Published: January 2020

Crude messenger ribonucleic acid fractions isolated from Corynebacterium diphtheriae and Escherichia coli were translated in an E. coli in vitro protein-synthesizing system and yielded precursors of the secreted proteins diphtheria toxin and alkaline phosphatase, respectively. Addition of inverted E. coli inner membrane vesicles to the system during the initial stages of translation resulted in the intravesicular segregation of mature diphtheria toxin and alkaline phosphatase. Outer membrane vesicles or inner membrane vesicles whose cytoplasmic surfaces had been treated with pronase could not mediate transmembrane transfer of diphtheria toxin or alkaline phosphatase. However, inner membrane vesicles isolated from E. coli spheroplasts which had been treated with pronase and inner membrane vesicles complexed with ribosomes during pronase treatment were functional in transmembrane transfer. At temperatures below the phase transition of E. coli membranes, no intravesicular segregation of alkaline phosphatase or diphtheria toxin was observed. The precursor forms of each protein accumulated free from the vesicles. These results suggest that an inner membrane protein, exposed on the cytoplasmic surface, plays an integral role in secretion.
Ultrastructure of methanotrophic yeasts
Authors: Wolf H J , Christiansen M , Hanson R S
Published: January 2020

The cellular structure of two yeast strains capable of growth on methane was investigated by electron microscopy. Microbodies were observed in cells of Sporobolomyces roseus strain Y and Rhodotorula glutinis strain CY when grown on methane but rarely when grown on glucose. The size of the microbodies and the number observed per cell in a thin section did not increase with culture age. No crystalline organization was observed within these organelles. Similar microbodies were also observed in cells of R. glutinis CY grown on hexadecane. The plasma membranes of both methane and hexadecane-grown cells exhibited increased invagination compared to that of glucose-grown cells. Catalase activity was detected in the microbodies of alkane-grown cells by using 3,3'-diaminobenzidine as a cytochemical stain. The data presented suggest that microbodies, and the catalase contained within them, play a role in eucaryotic methane metabolism.
Repair of x-ray-induced deoxyribonucleic acid single-strand breaks in xth mutants of Escherichia coli
Authors: Seeberg E , Steinum A L
Published: January 2020

An exonuclease III-deficient strain of Escherichia coli K-12, BW2001 (xthA11), was unable to perform rapid repair of X-ray-induced deoxyribonucleic acid single-strand breaks and appeared to have a defect in the priming of the 3'-termini necessary for initiation of repair synthesis at the breaks. This defect cannot be explained solely by the lack of exonuclease III activity, because other xth mutants tested, including a deletion mutant, repaired radiation-induced strand breaks at close to the normal rate.
Physical mapping of the Escherichia coli D-serine deaminase region: contiguity of the dsd structural and regulatory genes
Authors: Carothers A M , McFall E , Palchaudhuri S
Published: January 2020

The genes dsdA, dsdO, and dsdC have been located on a 3.0-kilobase pair (kb) fragment of the Escherichia coli chromosome by a combination of techniques. The loci were first cloned onto lambda and various plasmid vectors. dsd hybrid plasmids were then digested with restriction enzymes, and the fragments were recloned to test for the presence of dsdC or dsdA. In one case, a 4.2-kb restriction fragment containing the dsdA operon was used to form a heteroduplex with a well-defined lambda dsd deoxyribonucleic acid. The results show that dsdA, dsdO, and at least 0.6 kb of dsdC are present on this piece of deoxyribonucleic acid. On the basis of the mapping analysis and the molecular weight of D-serine deaminase, 1.9 kb of the 4.2-kb fragment is accounted for by the three dsd loci. We conclude that dsdO and dsdC are contiguous. A detailed dsd restriction map is presented.
Cell division of cycle of Bacillus subtilis: evidence of variability in period D
Authors: Holmes M , Rickert M , Pierucci O
Published: January 2020

In Bacillus subtilis the deoxyribonucleic acid content and the extent of cell division during inhibition of chromosome replication increased as a function of the average cell mass, independent of the growth rate. At each growth rate, mass, deoxyribonucleic acid, and residual division varied in different cultures. The variation is consistent with a large variability in the D period. At growth rates higher than 1.5 doublings per h at 37 degrees C, the change in D accounts for the growth rate dependence of the mass and deoxyribonucleic acid content.
Nuclear division cycle in Neurospora crassa hyphae under different growth conditions
Authors: Martegani E , Levi M , Trezzi F , Alberghina L
Published: January 2020

Treatment with picolinic acid blocked Neurospora crassa nuclei in G1, and recovery from the treatment allowed a synchronous wave of deoxyribonucleic acid synthesis to occur. Nuclei, which appeared as compact globular bodies during the period of blockage, assumed a ring shape during the following S phase, which was also maintained in the G2 phase. The proportion of compact globular nuclei was much higher in hyphae growing at lower rates, whereas that of ring nuclei increased when the hyphae were growing at higher rates. Horseshoe nuclei (probably mitotic nuclei) and double ring nuclei were also observed in growing hyphae, but their frequencies were low and fairly independent of the rate of growth. The length of the S phase of the Neurospora nuclear division cycle was determined to be about 30 min. From the frequencies of the phase-specific nuclear shapes, the durations of the G1 phase and the combined S plus G2 phases were calculated. The results showed that variations in the growth rates of the mycelia were mainly coupled with variations in the G1 phase of the nuclear division cycle. For mycelia growing in minimal sucrose, the lengths of all of the phases of the nuclear division cycle were estimated.
Chromosomal location of a gene for chemical longevity of messenger ribonculeic acid in a temperature-sensitive mutant of Escherichia coli
Authors: Ono M , Kuwano M
Published: January 2020

Genetic analysis of a thermolabile mutation affecting alteration of messenger ribonculeic acid stability indicates that the gene ams maps close to pyrC gene (23 min) on the Escherichia coli chromosome and has a cotransduction frequency of 29.6% with pyrC gene. The probable gene order is pyrD-ams-pyrC-purB.
Inhibitory effect of novobiocin on ribonucleic acid synthesis during germination of Bacillus subtilis spores
Authors: Matsuda M , Kameyama T
Published: January 2020

Novobiocin inhibited ribonculeic acid synthesis during germination of Bacillus subtilis spores. Transcription of certain kinds of genes probably required a preceding conformational change in deoxyribonucleic acid.
Effects of inositol starvation on phospholipid and glycan syntheses in Saccharomyces cerevisiae
Authors: Hanson B A , Lester R L
Published: January 2020

The early biochemical consequences of inositol starvation in an inositol auxotroph of Saccharomyces cerevisiae were examined as a means of determining the cellular role of inositol. Upon withdrawal of inositol, the rate of incorporation of 32P-labeled inorganic phosphate into phosphatidylinositol and into the phosphoinositol-containing sphingolipids immediately dropped by 80 and 50%, respectively; however, synthesis of the other major phospholipids continued for 2 to 3 h at control rates. The incorporation of [U-14C]glucose into cell wall glycans began to decline immediately poststarvation and decreased to 50% of the initial rate by 80 min for mannan and by 140 min for alkali- and acid-insoluble glucan. These changes in the rates of synthesis of cell wall glycan and phosphatidylinositol were the earliest effects of inositol starvation, preceding inhibition of the synthesis of protein and ribonucleic acid as measured by incorporation of radioactive precursors into trichloroacetic acid-insoluble cell material. These results suggest that phosphatidylinositol may play a direct role in the synthesis or secretion of yeast glycans.
Cloning and restriction mapping of the trmA gene coding for transfer ribonucleic acid (5-methyluridine)-methyltransferase in Escherichia coli K-12
Authors: Ny T , Björk G R
Published: January 2020

A hybrid plasmid from the Clarke and Carbon collection has been isolated. This plasmid carries the trmA gene of E. coli, which is necessary for the formation of 5-methyluridine (m5U,ribothymidine) present in all transfer ribonucleic acid (tRNA) chains of the organism so far sequenced. A restriction map of the argCBH-trmA regions is presented. By using cloning in vitro, the trmA gene was located on a 2.9-kilobase pair deoxyribonucleic acid (DNA) fragment. These results and comparison with lambda dargECBH transducing phages established the gene order: argECBH trmA bfe in the 88-min region of the E. coli chromosomal map. Plasmids carrying this 2.9-kilobase pair DNA fragment overproduce the enzyme tRNA(m5U)methyltransferase (EC 2.1.1.35) 20 to 40 times. When this 2.9-kilobase pair chromosomal DNA fragment was expressed in a minicell system, a polypeptide of a molecular weight of 42,000 was synthesized. This polypeptide was tentatively identified as the tRNA(m5U)methyltransferase. These results support the earlier suggestion that the trmA gene is the structural gene for the tRNA(m5U)methyltransferase.
Resistance to thiostrepton, siomycin, and sporangiomycin in actinomycetes that produce them
Authors: Thompson J , Cundliffe E
Published: January 2020

The antibiotics thiostrepton, siomycin, and sporangiomycin are closely related both in structure and in mode of action. Actinomycetes which produce this group of compounds possess ribonucleic acid-pentose methylases, which act upon 23S ribosomal ribonucleic acid and render ribosomes resistant to the action of these antibiotics. This is achieved via the formation of a single residue of 2'-O-methyladenosine per ribosome.
Mutants defective in isomerase and decarboxylase activities of the 4-hydroxyphenylacetic acid meta-cleavage pathway in Pseudomonas putida
Authors: Barbour M G , Bayly R C
Published: January 2020

Degradation of 2-hydroxy-5-carboxymethylmuconic semialdehyde, the ring fission product of the 4-hydroxyphenylacetate meta-cleavage pathway, by mutant strains P23X19 and P23X16 of Pseudomonas putida NCI B 9865 was studied. Both mutants were unable to grow on either 4-hydroxyphenylacetate of 3,4-dihydroxyphenylacetate. Cell extracts of P23X19, grown in the presence of 3,4-dihydroxyphenylacetate, degraded the ring fission product to a compound that accumulated and had maximum UV absorption at 300 nm, pH 7.4, and 345 nm, pH 12. These are the spectral characteristics of 2-keto-5-carboxymethylhex-3-ene-1,6-dioate, the substrate for the decarboxylase in this pathway. This observation is consistent with P23X19's being decarboxylase defective. Cell extracts of P23X16, grown in the presence of 3,4-dihydroxyphenylacetate, degraded the ring fission product to a compound that accumulated and has maximum UV absorption at 295 nm, pH 7.4, and 345 nm, pH 12. This compound spontaneously degraded to a compound with the spectral properties of the decarboxylase substrate. The compound accumulated by P23X16 was also obtained when the decarboxylase substrate was treated with borate. It is suggested that the compound accumulated by P23X16 is the substrate of an isomerase. The results are consistent with P23X16's being unable to synthesize a functional isomerase while retaining decarboxylase activity and establish the physiological importance of an enzyme-catalyzed isomerization in the meta-cleavage degradation of 4-hydroxyphenylacetate.
Integration of specialized transducing bacteriophage lambda cI857 St68 h80 dgnd his by an unusual pathway promotes formation of deletions and generates a new translocatable element
Authors: Wolf R E
Published: January 2020

Molecular and genetic studies have revealed that several illegitimate recombinational events are associated with integration of the specialized transducing bacteriophage lambda cI57 St68 h80 dgnd his into either the Escherichia coli chromosome or into a plasmid. Most Gnd+ His+ transductants did not carry the prophage at att phi-80, and 10% were not immune to lambda, i.e., "nonlysogenic." Integration of the phage was independent of the phage Int and Red gene products and of the host's general recombination (Rec) system. In further studies, bacterial strains were selected which carried the phage integrated into an R-factor, pSC50. Restriction endonuclease analysis of plasmid deoxyribonucleic acid (DNA) purified from these strains showed that formation of the hybrid plasmids resulted from recombination between a single region of pSC50 and one of several sites within the lambda-phi 80 portion of the phage. Furthermore the his-gnd region of the phage, present in the chromosome of one nonlysogenic transductant, was shown to be able to translocate to pSC50. Concomitant deletion of phage DNA sequences or pSC50 DNA was frequently observed in conjunction with these integration or translocation events. In supplemental studies, a 22- to 24-megadalton segment of the his-gnd region of the chromosome of a prototrophic recA E. coli strain was shown to translocate to pSC50. One terminus of this translocatable segment was near gnd and was the same as a terminus of the his-gnd segment of the phage which translocated from the chromosome of the nonlysogenic transductant. These data suggest that integration of lambda cI857 St 68 h80 dgnd his may be directed by a recombinationally active sequence on another replicon and that the resulting cointegrate structure is subject to the formation of deletions which extend from the recombinationally active sequence. Translocation of the his-gnd portion of the phage probably requires prior replicon fusion, whereas the his-gnd region of the normal E. coli chromosome may comprise a discrete, transposable element.
Regulation of fatty acid degradation in Escherichia coli: isolation and characterization of strains bearing insertion and temperature-sensitive mutations in gene fadR
Authors: Simons R W , Egan P A , Chute H T , Nunn W D
Published: January 2020

Transposon Tn10 was used to mutagenize the fadR gene in Escherichia coli. Mutants bearing fadR:Tn10 insertion mutations were found to (i) utilize the noninducing fatty acid decanoate as sole carbon source, (ii) beta-oxidize fatty acids at constitutive rates, and (iii) contain constitutive levels of the five key beta-oxidative enzymes. These characteristics were identical to those observed in spontaneous fadR mutants. The constitutive phenotype presented by the fadR:Tn10 mutants was shown to be genetically linked to the associated transposon-encoded drug resistance. These results suggest that the fadR gene product exerts negative control over the fatty acid degradative regulon. The fadR gene of E. coli has been mapped through the use of transposon-mediated fadR insertion mutations. The fadR locus is at 25.5 min on the revised map and cotransduces with purB, hemA, and trp. Three-factor conjugational and transductional crosses indicate that the order of loci in this region of the chromosome is purB-fadR-hemA-trp. Spontaneous fadR mutants were found to map at the same location. Strains that exhibit alterations in the control of the fad regulon in response to changes in temperature were also isolated and characterized. These fadR(Ts) mutants were constitutive for the fad enzymes at elevated temperatures and inducible for these activities at low temperatures. The fadR(Ts) mutations also map at the fadR locus. These results strongly suggest that the fadR gene product is a repressor protein.
Electrochemical proton gradient in Micrococcus lysodeikticus cells and membrane vesicles
Authors: Friedberg I , Kaback H R
Published: January 2020

Using the distribution of weak acids to measure the pH gradient (delta pH; interior alkaline) and the distribution of the lipophilic cation [3H]tetraphenylphosphonium+ to monitor the membrane potential (delta psi; interior negative), we studied the electrochemical gradient or protons (delta mu- H+) across the membrane of Micrococcus lysodeikticus cells and plasma membrane vesicles. With reduced phenazine methosulfate as electron donor, intact cells exhibited a relatively constant delta mu- H+ (interior negative and alkaline) of -193 mV to -223 mV from pH 5.5 to pH 8.5. On the other hand, in membrane vesicles under the same conditions, delta mu- H+ decreased from a maximum value of -166 mV at pH 5.5 to -107 mV at pH 8.0 and above. This difference is related to a differential effect of external pH on the components of delta mu- H+. In intact cells, delta pH decreased from about -86 mV (i.e., 1.4 units) at pH 5.5 to zero at pH 7.8 and above, and the decreases in delta pH was accompanied by a reciprocal increase in delta psi from -110 mV at pH 5.5 to -211 mV at pH 8.0 and above. In membrane vesicles, the decrease in delta pH with increasing external pH was similar to that described for intact cells; however, delta psi increased from -82 mV at pH 5.5 to only -107 mV at pH 8.0 and above.
Disposition of exposed antigens on the faces of isolated Mycoplasma gallisepticum membranes
Authors: Vinther O , Freundt E A
Published: January 2020

The transverse disposition of exposed protein antigens on the two faces of isolated Mycoplasma gallisepticum membranes have been investigated by using indirect immunoferritin labeling to accomplish visualization of the antigens at the ultrastructural level. Comparison between the labeling patterns obtained with unabsorbed specific mycoplasma antiserum and antiserum from which antibodies directed against outer side determinants had been removed revealed that the majority of protein antigens were the same on the opposed membrance faces or at least displayed extensive interside cross-reactivity. The relatively scarce tagging of isolated Acholeplasma laidlawii membranes, contrary to membranes on intact organisms observed in this investigation, precluded conclusions regarding the disposition of membrane antigens of this species. The advantages and limitations of the employed method in disposition studies and the factors influencing the transverse distribution of membrane proteins in mycoplasmas are discussed.
Regulation of ribonucleic acid polymerase synthesis during restriction of an Escherichia coli mutant temperature sensitive for transcription factor sigma
Authors: Blumenthal R M , Dennis P P
Published: January 2020

An Escherichia coli mutant temperature sensitive for the sigma subunit of ribonucleic acid polymerase was shifted to restrictive temperatures. In response to these restrictions the transcription of rpoBC increased markedly, and the synthesis rates of the beta and beta' subunits of ribonucleic acid polymerase increased. The ratio of the beta and beta' synthesis rates (beta/beta') decreased.
Asymmetrical division of Saccharomyces cerevisiae
Authors: Lord P G , Wheals A E
Published: January 2020

The unequal division model proposed for budding yeast (L. H. Hartwell and M. W. Unger, J. Cell Biol. 75:422-435, 1977) was tested by bud scar analyses of steady-state exponential batch cultures of Saccharomyces cerevisiae growing at 30 degrees C at 19 different rates, which were obtained by altering the carbon source. The analyses involved counting the number of bud scars, determining the presence or absence of buds on at least 1,000 cells, and independently measuring the doubling times (gamma) by cell number increase. A number of assumptions in the model were tested and found to be in good agreement with the model. Maximum likelihood estimates of daughter cycle time (D), parent cycle time (P), and the budded phase (B) were obtained, and we concluded that asymmetrical division occurred at all growth rates tested (gamma, 75 to 250 min). D, P, and B are all linearly related to gamma, and D, P, and gamma converge to equality (symmetrical division) at gamma = 65 min. Expressions for the genealogical age distribution for asymmetrically dividing yeast cells were derived. The fraction of daughter cells in steady-state populations is e-alpha P, and the fraction of parent cells of age n (where n is the number of buds that a cell has produced) is (e-alpha P)n-1(1-e-alpha P)2, where alpha = IN2/gamma; thus, the distribution changes with growth rate. The frequency of cells with different numbers of bud scars (i.e., different genealogical ages) was determined for all growth rates, and the observed distribution changed with the growth rate in the manner predicted. In this haploid strain new buds formed adjacent to the previous buds in a regular pattern, but at slower growth rates the pattern was more irregular. The median volume of the cells and the volume at start in the cell cycle both increased at faster growth rates. The implications of these findings for the control of the cell cycle are discussed.
Temperature-induced synthesis of specific proteins in Escherichia coli: evidence for transcriptional control
Authors: Yamamori T , Yura T
Published: January 2020

Synthesis of several protein chains of Escherichia coli is markedly, though transiently, induced upon shift-up of a log-phase culture to or above the critical temperature (about 34 degrees C). Such induction occurs coordinately for at least three protein chains (76K, 73K, and 64K) examined. Studies of initial kinetics of induction using a specific inhibitor of transcription (rifampin) revealed that induction occurs at the level of transcription with very little lag, though actual synthesis of messenger ribonucleic acids and proteins requires about 1 min when temperature is shifted up from 30 to 42 degrees C. Evidence suggests that E. coli cells somehow "recognize" the temperature change and activate transcription of several distinct operons, one of which contains the mop (morphogenesis of phages; groE) gene.
Chromosomally integrated conjugative plasmids are common in antibiotic-resistant Haemophilus influenzae
Authors: Stuy J H
Published: January 2020

Twenty-three highly antibiotic-resistant strains of Haemophilus influenzae and two of Haemophilus parainfluenzae without detectable large plasmids were examined for conjugative transfer of their resistance to H. influenzae strain Rd or to other strains. Very inefficient transfer was observed for 18 H. influenzae strains and 1 H. parainfluenzae strain. All H. influenzae transcipients carried a large plasmid, and they were in turn efficient donors of their resistances in standard conjugation crosses with isogenic recipients. This was not seen for the H. parainfluenzae transcipients. It is concluded that most of the original antibiotic-resistant cultures carried an integrated conjugative R plasmid which had been excised in a few cells in each population. It was these cells which transferred resistance in the primary crosses.
Agglutination of human erythrocytes by Fusobacterium nucleatum: factors influencing hemagglutination and some characteristics of the agglutinin
Authors: Dehazya P , Coles R S
Published: January 2020

Various aspects of agglutination of human erythrocytes by fusobacterium nucleatum were examined. Titration experiments done in buffered saline at pH 6 to 10 showed the same agglutination endpoint. The presence of high concentrations of NaCl in reaction mixtures did not alter titers, but KCl in concentrations of 0.5 to 3.6 M increased titers twofold. The agglutinin was inactivated by heat, acid, alkali, 5% Formalin, and the proteolytic enzyme subtilopeptidase A and therefore appeared to be a protein. Treatment of bacterial cells with 2-mercaptoethanol had no effect. Hemagglutination inhibition experiments revealed that arginine and other compounds containing a guanido group as part of their structure were inhibitory at low concentrations. Various hexoses, some hexose derivatives, and most common metal ions, when added to bacterium-erythrocyte mixtures, had no effect. The binding of dansyl-L-arginine to bacteria, but not erythrocytes, was demonstrable by ultraviolet fluorescence microscopy.
Assessment of Rhodopseudomonas sphaeroides chromatophore membrane asymmetry through bilateral antiserum adsorption studies
Authors: Collins M L , Mallon D E , Niederman R A
Published: January 2020

The asymmetric structure of the Rhodopseudomonas sphaeroides chromatophore membrane was examined in detail by crossed immunoelectrophoresis techniques. Because these methods are quantitative and allow increased resolution and sensitivity, it was possible to analyze simultaneously the relative transmembrane distribution of a number of previously identified antigenic components. This was demonstrated by analysis of immunoglobulin samples that were adsorbed by preincubation with either isolated chromatophores or osmotically protected spheroplasts. The photochemical reaction center, the light-harvesting bacteriochlorophyll a-protein complex, the L-lactate dehydrogenase, and reduced nicotinamide adenine dinucleotide dehydrogenase (EC 1.6.99.3) were found to be exposed on the chromatophore surface (cytoplasmic aspect of the membrane within the cell). Other antigenic components were found to be exposed on the surface of spheroplasts (periplasmic aspect of the in vivo chromatophore membrane). Antigens with determinants expressed on both sides of the chromatophore membrane were also identified. Charge shift crossed immunoelectrophoresis confirmed the suggested amphiphilic character of the pigment-protein complexes and identified several additional amphiphilic membrane components.
Subunits of succinyl-coenzyme A synthetase: coordination of production in Escherichia coli and discovery of a factor that precludes refolding
Authors: Wolodko W T , Brownie E R , Bridger W A
Published: January 2020

Succinyl-coenzyme A synthetase of Escherichia coli has an alpha 2 beta 2 subunit structure. By measuring reconstituted enzyme activity present after addition of purified alpha or beta subunits to cell extracts followed by refolding, we have shown that extracts contain no significant excess of either subunit species. This equivalence suggests that the expression of the respective structural genes for the subunits is coordinately controlled. The presence of cell extract does not affect the rate or extent of reassembly of the subunits, pointing to a high degree of specificity of mutual recognition by the refolding subunits. In the course of these experiments, we have detected the presence in cell extracts of a low-molecular-weight factor that specifically inactivates unfolded alpha or beta subunits or prevents their reassembly into catalytically active enzyme. Under conditions where the subunits are completely inactivated, the factor has no detectable effect on native or refolded tetrameric enzyme, suggesting that the factor may react only with unfolded protein.
Effect of temperature on Pseudomonas fluorescens chemotaxis
Authors: Lynch W H
Published: January 2020

The effects of temperature and attractants on chemotaxis in psychrotrophic Pseudomonas fluorescens were examined using the Adler capillary assay technique. Several organic acids, amino acids, and uronic acids were shown to be attractants, whereas glucose and its oxidation products, gluconate and 2-ketogluconate, elicited no detectable response. Chemotaxis toward many attractants was dependent on prior growth of the microorganism with these compounds. However, the organic acids, malate and succinate, caused strong chemotactic responses regardless of the carbon source used for growth of the bacteria. The temperature at which the cells were grown (30 or 5 degrees C) had no significant detectable effect on chemotaxis to the above attractants. The temperature at which the cells were assayed appeared to affect the rate but the extent of the chemotactic response, nor the concentration response curves. The ratios of the rate of accumulation of cells to the attractant malate were approximately 2, 4, and 1 at 30, 17, and 5 degrees C, respectively. Strong chemotactic responses were observed with cells assayed at temperatures approaching 0 degree C and appeared to be functional over a broad temperature range of 3 to 35 degrees C.
Isolation and partial characterization of the major outer membrane protein of Chromatium vinosum
Authors: Lane B C , Hurlbert R E
Published: January 2020

The 42,000 major outer membrane protein of Chromatium vinosum was purified by a combination on ion-exchange chromatography, gel filtration, and isoelectric focusing. Upon isoelectric focusing, the final material produced four major hands. Three of the four bands were isolated and analyzed for similarity or differences. Protease peptide maps and cyanogen bromide maps of the three isoelectric species were identical. When the isolated isoelectric species were refocused, each produced multiple isoelectric species, suggesting that the procedure used was generating the multiple charged species. Protease treatment of the isolated outer membrane produced a 31,000 fragment from the 42,000 protein. This fragment was isolated by preparative sodium sulfate-polyacrylamide gel electrophoresis. Although the amino acid compositions of the 42,000 protein and its 31,000 trypsin fragment were different, their polarity index was the same (45%). The amino-terminal sequences of the 42,000 protein and 31,000 trypsin fragment were identical, and it concluded that the amino-terminal was buried in the membrane.
Hydroxamate-mediated transport of iron controlled by ColV plasmids
Authors: Stuart S J , Greenwood K T , Luke R K
Published: January 2020

A new high-affinity system for iron transport, associated with the presence of ColV plasmids, has been detected in Escherichia coli and partially characterized. The presence of such "iron-transport plasmids" in E. coli cells that are defective in enterochelin-mediated transport of iron enabled them to grow in media to which 2,2'-dipyridyl had been added to reduce availability of iron. In addition, the presence of plasmid deoxyribonucleic acid in a mutant defective in enterochelin biosynthesis was associated with a marked increase in the rate of radioactive-iron uptake. Plasmid-determined uptake of iron was distinct from previously recognized systems for iron transport in E. coli K-12, and the colicin V molecule appeared not to be directly involved. Hydroxylamine-nitrogen could be detected in cell pellets of ColV+ cultures, and similar material was detected in supernatant fluids of late log- or stationary-phase cultures. The hydroxamate material was not detected in cell pellets or culture supernatants of strains from which plasmids had been eliminated, and a 95% decrease in hydroxamate synthesis was observed when cells were grown in minimal medium containing 2 microM iron.
Streptomyces viridochromogenes spore germination initiated by calcium ions
Authors: Eaton D , Ensign J C
Published: January 2020

Initiation of germination of heat-activated Streptomyces viridochromogenes spore occurs in media containing only calcium ions and organic buffer. The calcium-induced initiation of germination was accompanied by a decrease in absorbance of the spore suspension, an increased rate of endogenous metabolism, the loss of spore carbon, and the loss of heat resistance. Calcium amounts to 0.28% of the dry weight of freshly harvested spores. The amount of calcium remained the same after incubation of spores in water after heat activation. The spore content of calcium doubled after incubation in 0.5 mM CaCl2 for 5 min at 4 degrees C and during calcium-induced germination. Nearly all of the calcim appears to be bound to sites external to the spore membrane, since the chelating agents (ethylenedinitrilo) tetraacetic acid and arsenazo III removed virtually all of the calcium ions. The calcium ions must be present during the entire initiation of germination period. Germination ceases after an (ethylenedinitrilo) tetraacetic acid wash and begins again immediately after addition of calcium ions.
Azaserine resistance in Escherichia coli: chromosomal location of multiple genes
Authors: Williams M V , Kerr T J , Lemmon R D , Tritz G J
Published: January 2020

Resistance to azaserine in Escherichia coli is the result of mutations in at least three different loci. All spontaneously arising azaserine-resistant mutants harbor a lesion in the aroP gene. However, a lesion in this gene is not solely responsible for resistance. All spontaneously arising intermediate-level azaserine-resistant mutants also harbor a lesion in a gene designated azaA, which lies near min 43 on the chromosome. High-level resistant mutants harbor lesions in the aroP and azaA genes and in a third gene designated azaB, which lies near min 69 on the chromosome. Transport studies demonstrate that mutants harboring lesions in the azaA gene are not defective in the transport of the aromatic amino acids, but that mutants which harbor lesions in the azaB gene are defective in phenylalanine transport but not in tyrosine or tryptophan transport.
Heat evolution of microbial catabolism: effects of monooxygenases
Authors: Anderson J J , Dagley S
Published: January 2020

Heat evolved during microbial oxidation, expressed as a fraction of total energy available from each compound, was increased by monooxygenase participation. It was less for growth substrate catabolites than for their isomers.
Morphogenesis of the bacterial division septum: identification of potential sites of division in lkyD mutants of Salmonella typhimurium
Authors: Fung J C , MacAlister T J , Weigand R A , Rothfield L I
Published: January 2020

It previously has been shown that lkyD mutants of Salmonella typhimurium form large blebs of outer membrane over the septal and polar regions of dividing cells. To determine whether the outer membrane blebs are formed over potential sites of division even in the absence of septal ingrowth, lkyD strains were studied under conditions in which ingrowth of inner membrane and murein was prevented by inactivation of the envA gene product. In aseptate filaments of the LkyD EnvA strain, outer membrane blebs occurred with the usual frequency and were preferentially located over regions where new septa were formed when cell division was subsequently permitted to resume. The results indicate that the outer membrane blebs of the LkyD strain are markers for potential sites of cell division, implying that an alteration in association of outer membrane and murein exists in these sites before the initiation of septal ingrowth. This localized change in cell envelope organization is independent of the septation-inducing effects of the envA gene product.
Runaway replication of plasmid R1 is not caused by loss of replication inhibitor activity of gene cop
Authors: Molin S , Diaz R , Uhlin B E , Nordström K
Published: January 2020

The replication control functions of a mutant of plasmid R1 that replicates without control at temperatures above 35 degrees C have been analyzed. Although the mutations have not been mapped precisely, the data indicate that the gene (cop) previously identified on the wild-type plasmid (S. Molin and K. Nordström, J. Bacteriol. 141:111-120, 1980) as being responsible for expressing a trans-acting replication inhibitor, as well as for incompatibility of plasmid R1, is not affected in this mutant. Thus, the conditional lack of replication control observed in this plasmid mutant presumably is not caused by the loss of inhibitor activity of the cop gene.
Amplification of the tetracycline resistance determinant of plasmid pAM alpha 1 in Streptococcus faecalis: dependence on host recombination machinery
Authors: Yagi Y , Clewell D B
Published: January 2020

The plasmid pAM alpha 1 in Streptococcus faecalis was found to be severely impaired in its ability to exhibit amplification (generation of tandem repeats of the tetracycline resistance determinant during extended growth in the presence of tetracycline) when harbored by the recombination-deficient host cell UV202.
Isolation and Characterization of acetate kinase and phosphotransacetylase mutants of Escherichia coli and Salmonella typhimurium
Authors: LeVine S M , Ardeshir F , Ames G F
Published: January 2020

Mutations in the ack (acetate kinase) and pta (phosphotransacetylase) genes in Salmonella typhimurium were characterized and determined to be analogous to those of previously described Escherichia coli mutants. We established that in both bacterial species these genes were cotransducible with the neighboring histidine transport operon and were distally located relative to purF. pta mutants were sensitive to the dye alizarin yellow and were unable to grow on medium containing inositol as a carbon source. We selected mutants of both species with deletions covering both the ack and the pta genes; some deletions extended into the histidine transport operon.
Defective and plaque-forming lambda transducing bacteriophage carrying penicillin-binding protein-cell shape genes: genetic and physical mapping and identification of gene products from the lip-dacA-rodA-pbpA-leuS region of the Escherichia coli chromosome
Authors: Spratt B G , Boyd A , Stoker N
Published: January 2020

A series of defective lambda transducing phage carrying genes from the lip-leuS region of the Escherichia coli chromosome (min 14 on the current linkage map) has been isolated. The phage defined the gene order as lac---lip-dacA-rodA-pbpA-leuS---gal. These included the structural genes for penicillin-binding protein 2 (pbpA) and penicillin-binding protein 5 (dacA) as well as a previously unidentified cell shape gene that we have called rodA. rodA mutants were spherical and very similar to pbpA mutants but were distinguishable from them in that they had no defects in the activity of penicillin-binding protein 2. The separation into two groups of spherical mutants with mutations that mapped close to lip was confirmed by complementation analysis. The genes dacA, rodA, and pbpA lie within a 12-kilobase region, and represent a cluster of genes involved in cell shape determination and peptidoglycan synthesis. A restriction map of the lip-leuS region was established, and restriction fragments were cloned from defective transducing phage into appropriate lambda vectors to generate plaque-forming phage that carried genes from this region. Analysis of the proteins synthesized from lambda transducing phage in ultraviolet light-irradiated cells of E. coli resulted in the identification of the leuS, pbpA, dacA, and lip gene products, but the product of the rodA gene was not identified. The nine proteins that were synthesized from the lip-leuS region accounted for 57% of its coding capacity. Phage derivatives were constructed that allowed about 50-fold amplification of the levels of penicillin-binding proteins 2 and 5 in the cytoplasmic membrane.
Regulation of aromatic amino acid biosynthesis in Escherichia coli K-12: control of the aroF-tyrA operon in the absence of repression control
Authors: Camakaris H , Camakaris J , Pittard J
Published: January 2020

Evidence was found which indicated that a mutation in gene trpS affected the rate of synthesis of tyrosine-repressible 3-deoxy-D-arabinoheptulosonic acid-7-phosphate (DAHP) synthetase. The effect was found to occur independently of repression mediated by the tyrR gene product, and it was not due to a change in growth rate, nor was it a manifestation of the stringent response. It is proposed that in the proximal region of the aroF-tyrA operon there is an attenuator site controlled by the level of charged tryptophanyl-transfer RNA. In addition, it was demonstrated that starvation for certain amino acids led to degradation of tyrosine-repressible DAHP synthetase, but not phenylalanine-repressible DAHP synthetase, and supplementation with the missing amino acid led to an increased rate of synthesis of tyrosine-repressible DAHP synthetase during subsequent growth.
Levels of acid-soluble polyphosphate in growing cultures of Saccharomyces cerevisiae
Authors: Solimene R , Guerrini A M , Donini P
Published: January 2020

Short-chain acid-soluble polyphosphates were extracted from growing cultures of Saccharomyces cerevisiae, and the changes in the levels of these compounds were determined. The production of acid-soluble polyphosphates correlated with the mitochondrial activities since it occurred in two bursts in respiration-competent yeast cells and in only one burst in respiration-deficient yeast cells. The possible role of these compounds is discussed.
Outer membrane protein H1 of Pseudomonas aeruginosa: involvement in adaptive and mutational resistance to ethylenediaminetetraacetate, polymyxin B, and gentamicin
Authors: Nicas T I , Hancock R E
Published: January 2020

It is well established that Pseudomonas aeruginosa cells grown in Mg2+-deficient medium acquire nonmutational resistance to the chelator ethylenediaminetetraacetate and to the cationic antibiotic polymyxin B; this type of resistance can be reversed by transferring the cells to Mg2+-sufficient medium for a few generations. Stable mutants resistant to polymyxin B were isolated and shown to have also gained ethylenediaminetetraacetate resistance. Both the mutants and strains grown on Mg2+-deficient medium had greatly enhanced levels of outer membrane protein H1 when compared with the wild-type strain or with revertants grown in Mg2+-sufficient medium. It was determined that in all strains and at all medium Mg2+ concentrations, the cell envelope Mg2+ concentration varied inversely with the amount of protein H1. In addition, the increase in protein H1 in the mutants was associated with an increase in resistance to another group of cationic antibiotics, the aminoglycosides, e.g., gentamicin. We propose that protein H1 acts by replacing Mg2+ at a site on the lipopolysaccharide which can otherwise be attacked by the cationic antibiotics or ethylenediaminetetraacetate.
purF-lac fusion and direction of purF transcription in Escherichia coli
Authors: Smith J M , Gots J S
Published: January 2020

The purF locus codes for the first enzyme, glutamine phosphoribosylpyrophosphate amidotransferase, of the purine biosynthetic pathway. A strain of Escherichia coli K-12 was isolated in which the lac structural genes were fused to the control region of the purF locus. This purF-lac fusion was shown to respond to purine-specific regulatory signals. A plaque-forming lambda transducing phage bearing this purF-lac fusion was isolated. This phage was used to genetically determine the direction of transcription for the pufF locus by two independent means. Results from both methods agreed that the direction of transcription of the purF locus was clockwise on the standard Escherichia coli K-12 genetic map.