bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytochrome spectrum of an obligate anaerobe, Eubacterium lentum
Authors: Sperry J F , Wilkins T D
Published: January 2020

An obligately anaerobic bacterium, Eubacterium lentum, was shown to contain cytochromes a, b, and c and a carbon monoxide-binding pigment. Extracts of cells grown with hemin gave a typical absorption spectrum for cytochrome c with maxima at 424, 525, and 553 nm. Extracts from cells grown in the absence of hemin also had an absorption peak corresponding to cytochrome b (562 nm) in their reduced versus oxidized spectrum. Extraction of hemes and formation of pyridine hemochromes allowed quantitation of protoheme IX and heme c. Large amounts of cytochrome c masked the presence of cytochrome b in cells grown in medium containing hemin. When cells were grown in the presence of 50 mM nitrate, cytochrome A (606 nm) was detected. In anaerobic extracts of cells grown either with or without nitrate, cytochromes b and c were reduced by formate and oxidized by NO3. Cytochrome a appeared to be partially oxidized by NO3 and completely oxidized by air.
Production of extracellular ribonuclease by yeasts and yeastlike fungi, and its repression by orthophosphate in species of Cryptococcus and Tremella
Authors: Burt W R , Cazin J
Published: January 2020

A strain of Cryptococcus laurentii and a haploid isolate of Tremella foliacea were shown to produce orthophosphate-repressible ribonuclease in liquid culture. Addition of as little as 1 mM K2HPO4, pH 7.0, completely repressed enzyme production by both fungi. The orthophosphate-repressible enzyme was not produced by other species of the two genera tested. These results, together with other findings, suggest a close phylogenetic relationship between Cryptococcus laurentii and Tremella foliacea. The ability of other yeasts and yeastlike fungi to hydrolyze ribonucleic acid in a solid test medium was assessed. Based on the limited number of organisms available for study, extracellular ribonuclease activity was found in species having close affinity to the Basidiomycetes and in yeasts classified in the ascomycetous genera, Endomycopsis, Hansenula, and Kluyveromyces. Other ascomycetous yeasts did not exhibit extracellular ribonuclease.
Isolation and characterization of a mutant of Staphylococcus aureus deficient in autolytic activity
Authors: Chatterjee A N , Wong W , Young F E , Gilpin R W
Published: January 2020

A mutant of Staphylococcus aureus H (RUS3) uas isolated after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. The rate of autolysis of whole cells and isolated cell walls of RUS3 was less than 10% of the parent strain. In addition, the ability of the crude soluble enzyme isolated from RUS3 to degrade cell walls was negligible compared with the parent strain. The cell wall composition and the generation time of RUS3 were comparable to the parent strain. Unlike S. aureus H, RUS3 grew in clumps and did not undergo cell wall turnover. Both strains exhibited identical kinetics of killing by penicillin G. This may indicate that autolytic enzymes play a role in cell wall turnover and cell separation, but in S. aureus most of the autolytic activity is unrelated to the lethal effect of cell wall antibiotics.
Cell division in Pseudomonas aeruginosa: participation of alkaline phosphatase
Authors: Bhatti A R , DeVoe I W , Ingram J M
Published: January 2020

Pseudomonas aeruginosa grows at an apparent reduced rate at 46 C as compared with the rate at 37 C, when growth is measured as an increase in absorbance. Cells at 46 C are long, plasmolyzed, nonmotile filaments. The filaments contain phase-dark material that may be chromosomal in nature. When the 46 C culture is shifted to 37 C, the filaments fragment at polar ends after flagella form, and the final number of cells is equal to the number of chromosomal "packets" observed within the filament. The outer envelope of the filament appears to be structurally complete as determined by biochemical, thin section, and freeze-etch examination. When filaments are treated with lysozyme, they form large spheroplasts, suggesting that the outer wall and the cytoplasmic membrane are continuous within the filament. Filaments produce little or no periplasm-located alkaline phosphatase (APase), but activity appears immediately after a shift to 37 C. Cells grown at 37 C and shifted to 46 C remain as single, nonmotile, rods or doublets, and the APase formed at 37 C remains stable at 46 C. The addition of APase or inorganic phosphate is partially or completely effective as an inducer of filament fragmentation at 46 C. The results suggest that periplasm-located APase is an important enzyme in the final stages of cell division when P. aeruginosa is cultured on inorganic phosphate-limiting media.
Simplified Method for Interruption of Conjugation in
Escherichia coli
Authors: Zipkas David , Riley Monica
Published: January 2020

A simplified procedure is described in which interruption of mating and recombinant selection both take place on plates containing selective medium plus nalidixic acid.
Dissociation of Developing Slime Mold Cells Does Not Inhibit the Developmentally Regulated Rise in Alkaline Phosphatase Activity
Authors: Atryzek Vladimir
Published: January 2020

The rise in alkaline phosphatase activity after the resumption of development of dissociated slime mold cells is comparable to that found in non-dissociated aggregates.
Selective Methylation: an Incorrect Hypothesis
Authors: Shugart Lee
Published: January 2020

“Selective methylation,” a hypothesis proposed to explain the discrepancy found in the degree of methyl deficiency of transfer ribonucleic acid, cannot be explained on the basis of some biological phenomenon.
Specific ion concentration as a factor in barotolerant protein synthesis in bacteria
Authors: Smith W P , Landau J V , Pope D H
Published: January 2020

The degree of barotolerance exhibited by Pseudomonas fluorescens and Pseudomonas bathycetes in vitro polyphenylalanine-synthesizing systems can be modified by altering the concentrations of specific ions in the reaction mixture. Hybrid-protein-synthesizing systems, utilizing all the possible S-100 supernatant fluid and ribosome combinations from Escherichia coli, P. fluorescens, and P. bathycetes, were tested for barotolerance under conditions of low (16 mM Mg2+ plus 0 mM Na+) and high (150 mM Na+ plus 60 mM Mg2+) ion concentrations. The results reveal that barotolerant synthesis is a characteristic determined by the origin of the ribosome. Systems utilizing E. coli ribosomes are barosensitive at both low and high ion concentrations, P. fluorescens ribosomes barotolerant under both conditions, and P. bathycetes ribosomes barosensitive at low and barotolerant at high ion concentrations. Therefore, certain concentrations of specific ions will increase barotolerance, but only if the ribosomes are capable of functioning at high pressures.
Influence of exogenous sugars and polyols on C1-influx and efflux by the ascomycete Neocosmospora vasinfecta
Authors: Miller A G , Budd K
Published: January 2020

Glucose and other transportable sugars and polyols inhibited Cl- influx very soon after addition to mycelium in the process of Cl- accumulation. Under the usual experimental conditions (0.1 mM KCl, glucose greater than or equal to 2 mM) the mean percentage of inhibition of Cl- influx by glucose was 54.1 +/- 8.0 (+/- standard error; N = 26). Transport of the exogenous carbohydrate was necessary for inhibition of Cl- influx. Thus, the estimated Ki for glucose inhibition of Cl- influx (28 muM) was close to the Km for glucose transport; glycerol did not inhibit Cl- influx unless it was itself transported, and the degree of inhibition exerted by various carbohydrates correlated with their uptake rates. Inhibition was not caused by the accumulated sugar itself, as high levels (ca. 60 mM) of intramycelial 3-O-methylglucose gave rise to a stimulation of Cl- influx when the exogenous sugar was removed. It is suggested that interaction of Cl- and carbohydrate transport arises from competition for a common energy-coupling mechanism in the cell membrane. Both glucose and 3-O-methylglucose elicited Cl- efflux, but the maximal Cl- efflux rates were observed only after 40 min of incubation and only in the presence of the readily metabolizable glucose. Removal of the exogenous glucose, even after maximal Cl- efflux had been established, resulted in the rapid cessation of efflux. Studies under anaerobic conditions gave further evidence that glucose uptake was necessary and that efflux was not due to temporary depletion of energy reserves. It is proposed that glucose-induced leakage of Cl- is due to reversal of the Cl- uptake system, even though the Km for efflux is much greater than that for influx.
Control of tumbling in bacterial chemotaxis by divalent cation
Authors: Ordal G W
Published: January 2020

Chemotaxis is migration of organisms to higher concentrations of attractant or lower concentrations of repellent. Understanding the switch than controls whether the flagella rotate counterclockwise for swimming or clockwise for tumbling (thrashing about without making much forward progress) is central to understanding chemotaxis of peritrichous bacteria, since chemotaxis results from selective suppression of tumbles. Depletion of divalent cation by chelating agents in the presence of A23187, an ionophore that conveys divalent cation across membrane, causes incessant tumbling in Bacillus subtilis. Small additions of MgCl2 prevent this tumbling. In this tumbling condition, the bacteria which normally swim extensively when given attractant, do not respond even to 10 mM alanine, a strong attractant. MnCl2, by contrast to others potentiated by the ionophore. Permanent cations, including tetraphenylarsonium ion and triphenylmethylphosphonium ion, cause permanent swimming, even in the presence of A23187 and chelating agents. We propose that divalent cation, probably Mg2+ ion, binds to the switch to cause swimming and that, in the absence of divalent cation at the switch, the bacterium tumbles.
Role of deoxyribonucleic acid polymerases and deoxyribonucleic acid ligase in x-ray-induced repair synthesis in toluene-treated Escherichia coli K-12
Authors: Billen D , Hellermann G R
Published: January 2020

Toluene-treated Escherichia coli mutants have been used to study the roles of deoxyribonucleic acid (DNA) polymerases I, II, and III, and of DNA ligase in repair synthesis and strand rejoining following X-irradiation. In cells possessing all three DNA polymerases, both a greater amount of repair synthesis ("exaggerated" repair synthesis) and failure of ligation are observed when DNA ligase activity is inhibited. In a mutant lacking the polymerizing activity of DNA polymerase I, exaggerated repair synthesis is not observed, and strand rejoining does not occur even if DNA ligase is fully activated. In a mutant possessing the polymerizing activity of DNA polymerase I but lacking its 5'leads to 3' exonuclease activity, exaggerated repair synthesis is minimal. After irradiation, DNA polymerases II and III are capable of carrying out an adenosine 5'-triphosphate-dependent repair synthesis,but rejoining of strand breaks does not occur and exaggerated synthesis is not seen whether DNA ligase is active or not. These results suggest that DNA polymerase I and DNA ligase act together to limit repair synthesis after X irradiation and that both are necessary in toluene-treated cells for strand rejoining. DNA polymerases II and III apparently cannot complete chain elongation and gap filling, and therefore repair carried out by these enzymes does not respond to ligase action.
Plasmid-determined alcohol dehydrogenase activity in alkane-utilizing strains of Pseudomonas putida
Authors: Benson S , Shapiro J
Published: January 2020

We have identified an alcohol dehydrogenase activity in Pseudomonas putida strains carrying the CAM-OCT degradative plasmid that were grown on octane. The activity is nicotinamide adenine dinucleotide independent, sediments at 48,000 x g, and shows 20-fold greater activity with octanol rather than butanol as substrate. The enzyme is inducible by unoxidized alkane and is present only in strains that have the OCT plasmid genes for alkane degradation with a wild-type alcO locus. No analogous chromosomal dehydrogenase could be detected. Wild-type and actanol-negative mutants (alcA-) without plasmids both contain a constitutive nicotinamide adenine dinucleotide-linked soluble alcohol dehydrogenase activity. This means that alcA- mutants are cryptic for octanol oxidation and suggests that the particulate plasmid-coded alcohol dehydrogenase activity is active on surface- or membrane-bound substrate.
Relationship between hemagglutinin and sialidase from Clostridium perfringens CN3870: gel filtration of mutant and reverant activities
Authors: Rood J I , Wilkinson R G
Published: January 2020

Gel filtration of supernatant fluids, from the wild-type Clostridium perfringens, strain CN3870, and several of the mutants and reverants derived from this strain, showed that these mutants failed to product detectable amounts of still produced sialidase III activity. The reverants tested had regained the ability to produce approximately wild-type levels of the I and II forms of both activities. These results showthat there is a direct relationship between the production of the I form and hemagglutinin and sialidase activities and the production of the II form of these biologically active proteins. Models that explain the genetic basis for these results are discussed.
Periplasmic protein related to the sn-glycerol-3-phosphate transport system of Escherichia coli
Authors: Silhavy T J , Hartig-Beecken I , Boos W
Published: January 2020

Two-dimensional gel electrophoresis of shock fluids of Escherichia coli K-12 revealed the presence of a periplasmic protein related to sn-glycerol-3-phosphate transport (GLPT) that is under the regulation of glpR, the regulatory gene of the glp regulon. Mutants selected for their resistance to phosphonomycin and found to be defective in sn-glycerol-3-phosphate transport either did not produce GLPT or produced it in reduced amounts. Other mutations exhibited no apparent effect of GLPT. Transductions of glpT+ nalA phage P1 into these mutants and selection for growth on sn-glycerol-3-phosphate revealed a 50% cotransduction frequency to nalA. Reversion of mutants taht did not produce GLPT to growth on sn-glycerol-3-phosphate resulted in strains that produce GLPT. This suggests a close relationship of GLPT to the glpT gene and to sn-glycerol-3-phosphate transport. Attempts to demonstrate binding activity of GLPT in crude shock fluid towards sn-glycerol-3-phosphate have failed so far. However, all shock fluids, independent of their GLPT content, exhibited an enzymatic activity that hydrolyzes under the conditions of the binding assay, 30 to 60% of the sn-glycerol-3-phosphate to glycerol and inorganic orthophosphate.
Repair deficiency, mutator activity, and thermal prophage inducibility in dna-8132 strains of Bacillus subtilis
Authors: Sadaie Y , Narui K
Published: January 2020

A ts mutation, dna-8132 (Hara and Yoshikawa, 1973), in the region of chromosome replication origin of Bacillus subtilis was found to cause pleiotropic effects at a permissive temperature (30 C). Strains carrying this mutation were lethan at 48 C but exhibited higher spontaneous mutation frequency and a lower capacity for repairing radiation damages at 30C. Introduction of the polA59 (Gass et al., 1971) mutation further enhanced the repair deficiency and the mutator activity. These results suggest that the dna-8132 gene product may be directly involved in chromosome replication and repair. SPO2 lysogens carrying this mutation produced mature phages upon a temperature shift from 30 to 48 C. Phage production at nonpermissive temperature suggests that there are few defects in the precursors of deoxyribonucleic acid synthesis in the mutant.
Mutations affecting catabolite repression of the L-arabinose regulon in Escherichia coli B/r
Authors: Heffernan L , Bass R , Englesberg E
Published: January 2020

Expression of the L-arabinose regulon in Escherichia coli B/r requires, among other things, cyclic adenosine-3', 5'-monophosphate (cAMP) and the cAMP receptor protein (CRP). Mutants deficient in adenyl cyclase (cya-), the enzyme which synthesizes cAMP, or CRP (crp-) are unable to utilize a variety of carbohydrates, including L-arabinose. Ara+ revertants of a cya-crp- strain were isolated on 0.2% minimal L-arabinose plates, conditions which require the entire ara regulon to be activated in the absence of cAMP and CRP. Evidence from genetic and physiological studies is consistent with placing these mutations in the araC regulatory gene. Deletion mapping with one mutant localized the site within either araO or araC, and complementation tests indicated the mutants acted trans to confer the ability to utilize L-arabinose in a cya-crp- genetic background. Since genetic analysis supports the conclusion, that the mutant sites are in the araC regulatory gene, the mutants were designated araCi, indicating a mutation in the regulatory gene affecting the cAMP-CRP requirement. Physiological analysis of one mutant, araCi1, illustrates the trans-acting nature of the mutation. In a cya-crp- genetic background, araCi1 promoted synthesis of both isomerase, a product of the araBAD operon, and permease, a product of the araE operon. Isomerase and permease levels in araCi1 cya+ crp+ were hyperinducible, and the sensitivity of each to cAMP was altered. Two models are presented that show the possible mutational lesion in the araCi strains.
Properties of the entry and exit reactions of the beta-methyl galactoside transport system in Escherichia coli
Authors: Wilson D B
Published: January 2020

The Km, Vmax, and Ki of the entry reaction were determined for three substrates of the beta-methyl galactoside transport system: D-galactose, D-glycerol-beta-D-galactoside, and beta-methyl-D-galactoside. Although the data for D-galactose and D-glycerol-beta-D-galactoside followed simple Michaelis-Menten kinetics, the results for beta-methyl-D-galactoside deviated from Michaelis-Menten kinetics in that the Ki for beta-methyl-D-galactoside inhibition of both of the other two substrates was 10-fold greater than the Km for beta-methyl-D-galactoside entry. Furthermore, two partial mgl- strains retain 56% of the parental level of the beta-methyl-D-galactoside entry reaction, but only 12% of the parental level of transport of the other two substrates. The exit reaction of beta-methyl-D-galactoside was shown to be first order. It was stimulated sixfold when the cells were provided with an energy source. This stimulation required adenosine 5'-triphosphate or a related compound. The exit reaction was not altered by mutations in any of the three cistrons which inactivate the beta-methyl-D-galactoside entry reaction, was not increased by growth in the presence of inducers of the entry reaction, and was not repressed by growth on glucose. The striking differences between the entry and exit reactions suggest that they either use different carriers or that none of the three cistrons which are currently known to code for components of the beta-methyl galactoside transport system code for its membrane carrier.
Membranes of Rhodospirillum rubrum: isolation and physicochemical properties of membranes from aerobically grown cells
Authors: Collins M L , Niederman R A
Published: January 2020

Highly purified preparations of cytoplasmic and outer membrane were isolated from aerobically grown Rhodospirillum rubrum lysed by sequential treatment with lysozyme, ethylenediaminetetraacetate, and Brij 58. The membranes were resolved and separated from other cellular constitutents by a combination of velocity and isopyknic sedimentation in sucrose density gradients. On the basis of their appearance in electron micrographs and their protein profiles in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, these preparations appear to be quite similar to those obtained from other gram-negative bacteria. The cytoplasmic membrane fraction contained the majority of the total membrane-bound succinic dehydrogenase activity and was 10-fold enriched in b- and c-type cytochrome with respect to the outer membrane. The latter fraction was characterized by a much greater carbohydrate content and the presence of arachidic acid, which is typical of R. rubrum lipopolysaccharide. Their protein fatty acid, and overall chemical compositions suggested that these preparations were freer from cross-contamination than those obtained from R. rubrum with currently available methods.
Appearance of spore coat protein in the cell extracts of Bacillus subtilis asporogenic mutants
Authors: Uchida A , Kadota H , Schaeffer P
Published: January 2020

By use of the antigen-antibody techniques we have studied whether asporogenic mutants of Bacillus subtilis can synthesize the spore coat protein. Antibody specific to spore coat protein was prepared and used to demonstrate that the spore coat protein was synthesized at the early stage of sporulation. We report here that asporogenic mutants synthesize the spore coat protein.
Modified nucleosides of Bacillus subtilis transfer ribonucleic acids
Authors: Vold B
Published: January 2020

An analysis of the kinds and amounts of minor nucleosides of transfer ribonucleic acids (tRNA's) from Bacillus subtilis 168 trpC2 is presented. Identification and quantitation were accomplished using ion exclusion chromatography, thin-layer and paper chromatography, and ultraviolet absorption properties. Nucleosides and their amount in moles per 80 residues are as follows: guanosine (25.7), cytidine (22.0), adenosine (15.2), uridine (13.1), 5-methyluridine (0.98), pseudouridine (1.54), 1-methyladenosine (0.15), N6-methyladenosine (0.01), 7-methyladenosine (0.10), 2-methyladenosine (0.03), 7-methylguanosine (0.20), N2-methylguanosine (0.14), 1-methylguanosine (0.14), a methylated pyrimidine (0.17), a methylated derivative of N6-(delta 2-isopentenyl)adenosine (0.02), ribose methylated nucleosides (0.02), 4-thiouridine (0.12), 2-thio-5-(N-methylaminomethyl) (0.09), and an unknown thionucleoside (0.12). Although the composition is similar to that of Escherichia coli in the proportion of major nucleosides, the content of pseudouridine and 5-methyluridine, and the degree of base and ribose methylation, the composition is more similar to that of the tRNA's of yeast and higher organisms in its lower degree of thiolation, the presence of significant amounts of 1-methyladenosine, and the low levels of 2-methyladenosine and 6-methyladenosine. Therefore, the nucleoside composition of B. subtilis presents some different aspects from those usually given as characteristic for bacterial tRNA's. It is not known whether these differences are due to variation between bacterial species in general or related to the process of differentiation.
Study of tyrosine transfer ribonucleic acid modification in relation to sporulation in Bacillus subtilis
Authors: Menichi B , Heyman T
Published: January 2020

A reversal in the relative amounts of the two major species of tyrosine transfer ribonucleic acid (tRNATyr) (I and II) has been previously observed by others during the development of Bacillus subtilis. These species have been purified by benzoylated diethylaminoethyl-cellulose chromatography and were shown to differ by the modification of an adenosine residue (species I contains i6A and species II ms2i6A). As suggested by competitive hybridization assays, they might possess the same nucleotide sequence. A tRNATyr species lacking isopentenyl and methylthio moieties was not detected. The structural difference between species I and II was shown to be important for ribosome binding but not for charging. The extent of alteration during growth was studied in parallel with physiological events. Like sporulation, tRNATyr change is iron dependent. Moreover, when sporulation is prevented by an excess of glucose, the tRNATyr change is delayed as is the synthesis of enzymatic systems required for the onset of sporulation. tRNATyr change also demands unceasing protein synthesis.
Peptidoglycan biosynthesis in Micrococcus luteus (sodonensis): transglycosidase and phosphodiesterase activities in membrane preparations
Authors: Jensen S E , Campbell J N
Published: January 2020

Two enzyme activities involved in the biosynthesis of peptidoglycan in Micrococcus luteus (sodonensis), a transglycosidase and a phosphodiesterase, have been demonstrated in isolated membrane preparations. The transglycosidase activity promotes the in vitro synthesis of an uncross-bridged peptidoglycan that is completely susceptible to lysozyme. This in vitro-synthesized peptidoglycan consists of 76% "soluble" and 24% "insoluble" material. The soluble peptidoglycan is primarily a single low-molecular-weight species of approximately 20 disaccharide peptide units. "Insoluble" peptidoglycan, which likely represents newly synthesized material incorporated into an existing cell wall, was solubilized by butanol extraction, and the two were compared. The phosphodiesterase activity demonstrated in this system cleaves uridine diphosphate-N-acetylmuramyl-L-alanyl-D-isoglutamyl-L-lysyl-D-alanyl-D-alanine to yield N-acetylmuramyl-L-alanyl-D-isoglutamyl-L-lysyl-D-alanyl-D-alanine plus uridine 5'-monophosphate plus inorganic phosphate. This phosphodiesterase activity, not detected under normal transglycosidase assay conditions, is a recycling mechanism and acts indirectly through formation and subsequent cleavage of a lipid-linked intermediate.
Expression of a mutation affecting F incompatibility in the integrated but not the autonomous state of F
Authors: Pfister A , DeVries J K , Maas W K
Published: January 2020

Previously we have described a mutant Hfr strain in which incompatibility between the integrated F factor and an autonomous F-prime (F') factor was abolished. The mutation (inc) was located in the integrated F factor. F-prime factors isolated from the mutant Hfr strain have the same incompatibility behavior as those isolated from normal Hfr strains. Reintegration of these F' factors into the chromosome restores the Inc- phenotype characteristic of the mutant Hfr. The inc mutation thus affects incompatibility between integrated F and autonomous F(Fi-Fa incompatibility) but not incompatibility between two autonomous F factors (Fa-Fa incompatibility). The implications of this finding for the mechanism of plasmid incompatibility are discussed.
Catabolism of L-tyrosine by the homoprotocatechuate pathway in gram-positive bacteria
Authors: Sparnins V L , Chapman P J
Published: January 2020

A metabolic pathway for L-tyrosine catabolism involves 3,4-dihydroxyphenylacetic acid (homoprotocatechuic acid) as substrate for fission of the benzene nucleus. Cell extracts of an organism tentatively identified as a Micrococcus possessed the enzymes required for degrading homoprotocatechuate to succinate and pyruvate, and stoichiometry was established for several of these reactions. When the required coenzymes were added, cell extracts degraded L-tyrosine to the ring-fission product of homoprotocatechuate 2,3-dioxygenase and also converted 4-hydroxyphenylpyruvic acid into 4-hydroxyphenylacetic acid. This compound, in turn, gave stoichiometric amounts of the ring-fission product of homoprotocatechuate by the action of a nicotinamide adenine dinucleotide phosphate-dependent 3-hydroxylase coupled with homoprotocatechuate 2,3-dioxygenase. Evidence is presented that this route for L-tyrosine catabolism is taken by five other gram-positive strains, including Micrococcus lysodeikticus and a species of Bacillus. Five other gram-positive bacteria from other genera employed the alternative homogentisate pathway.
Isolation and characterization of membranes from a hydrocarbon-oxidizing Acinetobacter sp
Authors: Scott C C , Makula S R , Finnerty W R
Published: January 2020

Membranes were isolated and purified from nutrient broth-yeast extract- and hexadecane-grown cells of Acinetobacter sp. strain HO1-N. Two membrane fractions were isolated from nutrient broth-yeast extract-grown cells, the cytoplasmic membrane and the outer membrane. In addition to these two membrane fractions, a unique membrane fraction was isolated from hexadecane-grown cells (band 1) and characterized as a lipid-rich, low-density membrane containing high concentrations of hexadecane. The outer membrane preparations of Acinetobacter, obtained from nutrient broth-yeast extract- and hexadecane-grown cells, exhibited a low ratio of lipid phosphorus to protein and contained phospholipase activity and 2-keto-3-deoxyoctulosonic acid. Phosphatidic acid cytidyltransferase, adenosine triphosphatase, and reduced nicotinamide adenine dinucleotide oxidase were recovered almost exclusively in the cytoplasmic membrane fractions. The cytoplasmic membrane fractions contained 20 to 25 polypeptide species on sodium dodecyl sulfate-polyacrylamide gels, and the outer membrane fractions contained 15 to 20 polypeptide species. A major polypeptide species with an apparent molecular weight of approximately 42,000 to 44,000 was found for all outer membrane fractions. The buoyant densities of the cytoplasmic membrane fractions and the outer membrane fractions were closely similar, necessitating their separation by differential centrifugation. Band 1 of hexadecane-grown cells had a ratio of lipid phosphorus to protein that was almost twice that of cytoplasmic membrane and a correspondingly low buoyant density (1.086 g/cm3). Enzyme activities associated with band 1 were identical to those associated with the cytoplasmic membrane. The electrophoretic banding pattern of band 1 was essentially identical to the banding pattern of the cytoplasmic membrane. The phospholipid and neutral lipid compositions of the isolated membrane fractions were determined as qualitatively similar, with significant quantitative differences. The ultrastructure characteristics of the respective membrane fractions were examined by the negative-stain technique.
Control of the synthesis of alkaline phosphatase and the phosphate-binding protein in Escherichia coli
Authors: Willsky G R , Malamy M H
Published: January 2020

Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunological techniques, we have compared the synthesis of the phoA protein (alkaline phosphatase) and the phoS protein (phosphate-binding protein) in response to the level of phosphate in the medium in different genetic backgrounds containing the known alkaline phosphatase control mutations. Both proteins are produced in excess phosphate media in a phoR1a- strain, whereas neither protein is produced in a phoB- strain even under derepression conditions. In four different phoR1c- strains, however, the phoA product cannot be detected in extracts of cells obtained from any growth condition, whereas the phoS product is produced in both excess and limiting phosphate media. It is not yet known if phoR1c- mutants are a special class of mutations within the phoB gene or whether they occur in a separate cistron involved in alkaline phosphatase regulation. From these results we conclude that the expression of the phoA gene is not always co-regulated with expression of the phoS gene product. We have determined that the phoS protein is a component of periplasmic protein band P4 described by Morris et al. (1974). The phoS product lacks sulfur-containing amino acids and is extractable by treatment with polymyxin sulfate. The other component of band P4 contains methionine and/or cysteine and is not extracted by polymyxin sulfate treatment. Like the phoS and phoA proteins, its synthesis is sensitive to the concentration of phosphate in the growth medium. In addition, the existence of a new class of periplasmic proteins synthesized at maximum rate in high phosphate media is demonstrated.
Co-regulation of the phosphate-binding protein and alkaline phosphatase synthesis in Escherichia coli
Authors: Yagil E , Silberstein N , Gerdes R G
Published: January 2020

In phosphate-starved cells of Escherichia coli, the synthesis of alkaline phosphatase and some additional periplasmic proteins is derepressed. One of these proteins, which does not appear in a phoS- constitutive strain, has been identified as well the periplasmic phosphate-binding protein.
Partial characterization of nucleoids and nucleoid-plasmid complexes from Salmonella typhimurium
Authors: Manis J J , Miller J R , Kline B C
Published: January 2020

Nucleoids from Salmonella typhimurium strain LT2 consist of supercoiled deoxyribonucleic acid structures that are ribonuclease labile sedimenting at 1,700S. More than 90% of the covalently closed circular deoxyribonucleic acid of a cryptic plasmid harbored by this strain cosediments with the host's 1,700S nucleoids.
Bacterial Characteristics Determining the Potential Host Range of Bacteriophage T4
Authors: Dawes Joan
Published: January 2020

Many members of theEnterobacteriaceae, but not other gram-negative organisms, apparently carry a specific recognition site for the T4 tail tube on their cytoplasmic membranes.
Physiological and genetic regulation of the aldohexuronate transport system in Escherichia coli
Authors: Nemoz G , Robert-Baudouy J , Stoeber F
Published: January 2020

In Escherichia coli K-12, the specificity of the aldohexuronate transport system (THU) is restricted to glucuronate and galacturonate. There is a relatively high basal-level activity in uninduced wild-type or isomeraseless strains. Supplementary activity is obtained with the inducers mannonic amide (five-fold), galacturonate (fourfold), fructuronate (fivefold), and tagaturonate (sevenfold). Specific THU- mutants were selected as strains unable to grow on either aldohexuronate but able to grow on fructuronate or tagaturonate. The remaining transport activity in uninduced and induced THU- starins represents less than 20% of that found in the wild type. Conjugation and transduction experiments indicate that all of the THU- mutations are located in a unique locus, exuT, half-way between the tolC (59 min) and argG (61 min) markers. exuT is closely linked to the uxaC-uxaA operon (60 min) and to the regulatory gene exuR (60 min), which controls the above-mentioned operon and the uxaB operon (45 min). Growth on either aldohexuronate and transport activity are fully recovered when exuT mutants are allowed to revert to exuT+ on galacturonate or glucuronate. Reversion on glucuronate alone may lead to the mutational derepression of the 2-keto-3-deoxygluconate transport system, which is uninducible in the wild type, which also takes up glucuronate, and whose structural gene belongs to the kdg regulon. Such strains, which remain unable to grow on galacturonate, are exuT and kdgR (constitutive allele of the regulatory gene kdgR of the kdg regulon). THU activity is superrepressed in an exuR mutant in which the uxaC-uxaA operon and the uxaB operon are superrepressed; exuR+/exuR merodiploids are also superrepressed. In a thermosensitive exuR mutant in which the above-mentioned operons are constitutive at 42 degrees C, the THU activity is fully derepressed at this temperature. On the basis of these and other results, it is concluded that THU is coded for by the structural gene exuT, which is negatively controlled by the exuR gene product and which probably belongs to an operon distinct from the uxaA-uxaC operon.
Characterization of an Acholeplasma laidlawii variant with a REP- phenotype
Authors: Nowak J A , Das J , Maniloff J
Published: January 2020

An Acholeplasma laidlawii variant has been isolated that has a REP- phenotype. The properties of this variant, relative to parental cells, are: (i) it exhibits no change in cell growth kinetics; (ii) it does not propagate single-stranded deoxyribonucleic acid (DNA) mycoplasmaviruses but does propagate double-stranded DNA mycoplasmaviruses; (iii) it converts parental circular single-stranded mycoplasmavirus DNA to double-stranded replicative forms that are not replicated further; (iv) it exhibits no change in host modification and restriction; and (v) it has an increased ultraviolet light sensitivity. The REP- isolate is the first stable mycoplasma variant to which a physiological defect has been attributed.
Strain-specific variation in the protein and lipopolysaccharide composition of the group B meningococcal outer membrane
Authors: Frasch C E , McNelis R M , Gotschlich E C
Published: January 2020

Variation in the protein and lipopolysaccharide composition of the meningococcal outer membrane may be due to either serotype differences or to changes in cultural conditions. There are 12 antigenically distinct serotypes of group B meningococci, and these are associated with distinct major outer membrane protein patterns on sodium dodecyl sulfate-polyacrylamide gels. In most strains the predominant outer membrane protein carries the serotype-specific determinant. Certain strains, when grown under similar conditions in different media showed an altered membrane composition. The type 2 strain, M986, grown in modified Frantz medium-A, had a reduced amount of the major 41,000-dalton protein while a 28,000-dalton protein predominated. The altered protein composition may be related to changes in cell metabolism as reflected by the pH of the medium after growth. Growth of the organism in Frantz medium-B caused a negligible drop in pH and the 41,000-dalton protein remained predominant. There was also variation associated with changes in the growth rate. Increasing the aeration caused a concomitant increase in growth rate and cell yield. We observed two quantitative changes in outer membrane proteins in four of seven strains examined: (i) where only a single major protein changed (three strains), and (ii) where an increase in one protein component was associated with a decrease in another protein (one strain). When the strains were grown in tryptic soy broth (Difco Laboratories, Detroit, Mich.) with either high or low aeration, the total protein in the outer membrane remained constant. In contrast, with high aeration there was a significant increase in lipopolysaccharide. These studies suggest that the cell surface proteins may be altered by the organism to meet a variety of environmental conditions.
Outer membrane of Escherichia coli K-12: differentiation of proteins 3A and 3B on acrylamide gels and further characterization of con (tolG) mutants
Authors: Manning P A , Reeves P
Published: January 2020

Two classes of mutants, con and tolG, that appeared to be very similar in a number of respects have been shown to be identical and cotransducible with pyrD. By diethylaminoethyl-cellulose chromatography of the outer membranes, we have shown that the mutants are missing only protein 3A and retain protein 3B. Using con mutants, we were thus able to identify protein 3B on the pH 7.2 gel system of Maizel where it runs separately from protein 3A if unheated samples are used. tolG mutants were shown to be identical to con mutants in being conjugation defective with most F-like plasmid donors but not with I-like plasmid donors, and in their resistance pattern to bacteriophages and colicins. During the course of this study, it was observed that the bacteriocin produced by Serratia marcescenc JF246 was identical in its activity spectrum to colicin L-398 and is now considered to be a colicin of type L.
Organization of mesosomes in fixed and unfixed cells
Authors: Higgins M L , Tsien H C , Daneo-Moore L
Published: January 2020

After the addition of glutaraldehyde (GA) to cells incubated at 3 or 37 degrees C, mesosomes were observed with increasing frequencies in freeze fractures of cells. These increases were related to the kinetics with which GA cross-linked adjacent amino acids. Upon the addition of GA, mesosomes were first observed in the periphery of freeze-fractured cells usually attached to septal membranes. However, the time, while the septal attachment sites were maintained, the "bodies" of the mesosomes were observed to move toward the center of the cytoplasm. This centralization process was much more rapid at 37 than at 3 degrees C. It is hypothesized that upon fixation, or receipt of some physical insult, mesosome precursors found in undisturbed cells undergo a change in state that results in their visibility in freeze fractures.
Growth inhibition of Proteus mirabilis by cyclic adenosine 3'-5'-monophosphate
Authors: Schwarzhoff R H , Williams F D
Published: January 2020

Growth of Proteus mirabilis on a synthetic agar medium containing either glycerol, galactose, or trehalose as the sole source is inhibited by 5 mM cyclic adenosine 3',5'-monophosphate (cAMP). Inhibition on an agar medium is evident as loss of viability, but in broth cAMP only slightly inhibits growth rate. Inhibition is associated with the accumulation of methylglyoxal in the medium. A nonswarming mutant of P. mirabilis is not inhibited by cAMP on either of the three carbon sources, but it is sensitive to exogenous methylglyoxal.
Regulation of ribonucleic acid synthesis in spheroplasts, cold-shocked cells, and toluene-treated cells of Escherichia coli
Authors: Kimura A
Published: January 2020

The effects on the stringent control of ribosomal ribonculeic acid synthesis of the removal of cell wall, cold-shock treatment of cells, LiCl treatment of toluene-treated cells, and hypotonic treatment of spheroplasts were examined using Escherichia coli rel+ cells. Neither the removal of cell wall with penicillin or lysozyme nor the cold-shock treatment of the cells had an effect on the stringent control. The control mechanism, however, disappeared after the LiCl treatment of the toluene-treated cells, with the release of some protein component(s), possibly from the cytoplasmic membrane. The hypotonic and other treatments of spheroplasts, which disrupt the cytoplasmic membrane, also led to the abolishment of the control mechanism. These results suggested that the operation of the stringent control of ribosomal ribonucleic acid synthesis requires the cytoplasmic membrane, in which some proteins labile with LiCl treatment are embedded.
Biosynthesis of saturated and unsaturated fatty acids by a T-strain mycoplasma (Ureaplasma)
Authors: Romano N , Rottem S , Razin S
Published: January 2020

A human T mycoplasma (Ureaplasma urealyticum) incorporated radioactivity into its lipids from [1-14C]acetate in the growth medium. Methanolysis of the lipids showed the label to be confined almost entirely to the methyl esters of the fatty acids. About 80% of the label was associated with the methyl esters of the saturated fatty acids, and the rest was found in the unsaturated methyl ester fraction. Gas-liquid chromatography of the saturated methyl esters showed the label to be present in the peaks of palmitate, myristate, and stearate, whereas in the unsaturated methyl ester fraction most of the radioactivity emerged in the peak of palmitoleate. The addition of either oleic or palmitic acid to the growth medium markedly decreased the organisms' incorporation of radioactivity from acetate. It is concluded that the T mycoplasma strain is capable of de novo synthesis of both saturated and unsaturated fatty acids, in this respect differing from all of the Mycoplasma and Acholeplasma strains investigated to date.
Regulation of histidinol phosphate aminotransferase synthesis by tryptophan in Bacillus subtilis
Authors: Weigent D A , Nester E W
Published: January 2020

The effect of tryptophan on the synthesis of histidinol phosphate aminotransferase and prephenate dehydrogenase has been examined. The genes specifying two enzymes for tryptophan biosynthesis (anthranilate synthase and tryptophan synthase-B) were found to be derepressed in a temporal sequence according to their chromosomal location. The genes for histidinol phosphate aminotransferase and prephenate dehydrogenase were derepressed simultaneously approximately 8 min after tryptophan synthase-B. When excess tryptophan was added to a derepressed culture, the pattern of repression of trpE (anthranilate synthase), trpB (tryptophan synthase-B), hisH (histidinol phosphate aminotransferase), and tyrA (prephenate dehydrogenase) was found to be simultaneous. Methyl tryptophan-resistant mutants, which synthesize elevated levels of the tryptophan enzymes, also synthesized elevated levels of histidinol phosphate aminotransferase. Qualitatively similar data were obtained in a temperature-sensitive tryptophanyl-transferase ribonucleic acid synthetase mutant grown at elevated temperatures. The time at which messenger ribonucleic acid was synthesized for anthranilate synthase, tryptophan synthase-B, histidinol phosphate aminotransferase, and prephenate dehydrogenase in the presence of actinomycin D indicated that ordered enzyme synthesis was a result of ordered transcription of the corresponding portion of the genome. The effect of the drug rifampin on enzyme synthesis was also examined. The addition of this drug halted the transcription of anthranilate synthase very rapidly, but later regions of the tryptophan region continued to be transcribed. The transcription of the hisH and tyrA genes was also shut off rapidly after rifampin was added. The significance of these observations to the control of transcription of the hisH gene by tryptophan is discussed.
Inhibition of glucose metabolism by n-hexadecane in Cladosporium (Amorphotheca) resinae
Authors: Siporin C , Cooney J J
Published: January 2020

When Cladosporium resinae is provided with n-hexadecane and glucose, n-hexadecane is used preferentially. Studies using [14C]glucose indicated that n-hexadecane did not inhibit glucose uptake but did retard oxidation of glucose to CO2 and assimilation of glucose carbon into trichloroacetic acid-insoluble material. Glucose could be recovered quantitatively from hydrocarbon-grown cells that had been transferred to glucose. Four enzymes that may be involved in glucose metabolism, hexokinase, glucose-6-phosphate dehydrogenase, glucose-phosphate isomerase, and succinate dehydrogenase, were not detected in cells grown on hexadecane but were present in cells grown on glucose. Addition of hexadecane to extracts of glucose-grown cells resulted in immediate loss of activity for each of the four enzymes, but two other enzymes did not directly involved in glucose metabolism, adenosine triphosphatase and alanine-ketoacid aminotransferase, were not inhibited by hexadecane in vitro. Cells grown on hexadecane and transferred to glucose metabolize intracellular hexadecane; after 1 day, activity of hexokinase, glucose-6-phosphate dehydrogenase, glucosephosphate isomerase, and succinate dehydrogenase could be detected and 22% of the intracellular hydrocarbon had been metabolized. Hexadecane-grown cells transferred to glucose plus cycloheximide showed the same level of activity of all the four enzymes as cells transferred to glucose alone. Thus, intracellular n-hexadecane or a metabolite of hexadecane can inthesis of those enzymes is not inhibited.