bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical structure of peptidoglycan in Selenomonas ruminantium: cadaverine links covalently to the D-glutamic acid residue of peptidoglycan
Authors: Kamio Y , Itoh Y , Terawaki Y
Published: January 2020

The peptidoglycan of Selenomonas ruminantium, a strictly anaerobic bacterium, contains cadaverine (Y. Kamio, Y. Itoh, Y. Terawaki, and T. Kusano, J. Bacteriol. 145:122-128, 1981). This report describes the chemical structure of the peptidoglycan of this bacterium. The [14C]cadaverine-labeled peptidoglycan was degraded with the lytic enzymes prepared from Streptomyces albus G into three small fragments including a major fragment (band A compound). Bank A compound was composed of L-alanine, D-glutamic acid, meso-diaminopimelic acid, D-alanine, and cadaverine in the molar ratio 0.98:1.0:1.0:0.98:0.97. Diaminopimelic acid, L-alanine, and cadaverine were N-terminal residues in band A compound. When the [14C]cadaverine-labeled band A compound was subjected to partial acid hydrolysis, two peptide fragments were obtained. One of them consisted of diaminopimelic acid and D-alanine; diaminopimelic acid was the N-terminal amino acid, and the other fragment was composed of L-alanine, D-glutamic acid, and cadaverine, of which L-alanine and cadaverine were N-terminal. These results lead us to conclude that the primary peptide structure of band A compound is L-alanyl-D-glutamyl-meso-diaminopimelyl-D-alanine and that cadaverine links covalently to the D-glutamic acid residue.
Cell wall composition of Micromonospora olivoasterospora, Micromonospora sagamiensis, and related organisms
Authors: Kawamoto I , Oka T , Nara T
Published: January 2020

Cell walls of 19 Micromonospora species were analyzed for their components. All the cell walls had xylose and arabinose, but the presence of glucose, galactose, mannose, or rhamnose depended on the strain. Amino acids present in the walls consisted of glycine, glutamic acid, diaminopimelic acid, and alanine, in a molar ratio of approximately 1:1:1:0.6--0.8. 3-Hydroxydiaminopimelic acid, together with meso-diaminopimelic acid, was found in many species and was isolated from Micromonospora olivoasterospora to compare the color constant in an amino acid analyzer with that of meso-diaminopimelic acid. The cell walls of Micromonospora sagamiensis and M. olivoasterospora contained only D-alanine and not L-alanine. All species tested except Micromonospora globosa contained glycolate in an almost equimolar ratio to diaminopimelic acid in their cell walls. Among 45 strains of 12 genera examined, Actinoplanes, Ampullariella, Amorphosporangium, and Dactylosporangium species had a significant amount of glycolate in the whole cells. Based on these results, the primary structure of the peptidoglycan of Micromonospora is discussed.
Role of ribonucleic acid synthesis in conjugational transfer of chromosomal and plasmid deoxyribonucleic acids
Authors: Maturin L J , Curtiss R
Published: January 2020

A strain of Escherichia coli K-12 containing mutations that allow for the experimental control of RNA and DNA syntheses was constructed to investigate the role that RNA synthesis plays in conjugational DNA transfer when DNA replication is inhibited. The mutations possessed by this strain and its donor derivatives include: (i) thyA, which blocks synthesis of dTMP, causing a requirement for thymine; (ii) deoC, which blocks breakdown of deoxyribose 5-phosphate, permitting growth with low levels of thymine; (iii) pyrF, which blocks synthesis of UMP from OMP, imposing a requirement for uridine; (iv) cdd and pyrG, which block the deamination of cytidine to uridine and the synthesis of CTP from UTP, respectively, causing a requirement for cytidine; (v) codA and codB, which block the deamination of cytosine to uracil and cytosine transport, respectively, preventing the substitution of cytosine for cytidine; and (vi) dnaB, which blocks vegetative but not conjugational DNA replication at 42 degrees C. DNA synthesis can be blocked in the donor strains by the addition of excess uridine when exogenous thymine is not present. We found that RNA synthesis can also be blocked by addition of excess uridine when exogenous cytidine is not present. Blocking RNA synthesis prior to mating, under conditions in which DNA synthesis either is or is not inhibited, depresses DNA transfer. However, under conditions in which DNA synthesis is inhibited, the blocking of RNA synthesis immediately after mating has commenced had no effect on continued conjugational transfer of DNA. Thus, RNA synthesis is needed to initiate but not to continue conjugational DNA transfer.
Serine utilization by Klebsiella aerogenes
Authors: Vining L C , Magasanik B
Published: January 2020

Klebsiella aerogenes was found to contain a specific L-serine dehydrase that was induced by threonine, glycine or leucine, but not by its substrate. Cellular concentrations were sensitive to carbon rather than nitrogen sources in the growth medium. A nonspecific isoleucine-sensitive L-threonine dehydrase supplemented the specific L-serine dehydrase activity. K. aerogenes also contains a leucine-inducible L-threonine dehydrogenase which probably initiated a threonine-utilization pathway in which the serine-specific dehydrate participated. Strains that were altered in their ability to metabolize serine differed in either L-serine dehydrase or L-threonine dehydrase activity. Thus, K. aerogenes growing on L-serine as a sole nitrogen source relies upon two enzymes that metabolize the amino acid as subsidiary functions.
Cloning and restriction mapping of the alkaline phosphatase structural gene (phoA) of Escherichia coli and generation of deletion mutants in vitro
Authors: Inouye H , Michaelis S , Wright A , Beckwith J
Published: January 2020

The structural gene for alkaline phosphatase (phoA) of Escherichia coli was cloned into the PstI site of pBR322, from a transducing bacteriophage, lambda p(phoA-proC). The restriction map of the plasmid was established. Based upon this information, several phoA deletion plasmids as well as a smaller phoA+ plasmid were constructed. The genetic map and restriction map were correlated by recombination analysis. Cells carrying one of the phoA+ plasmids overproduce alkaline phosphatase 10-fold upon phosphate limitation. However, both regulation and processing of the enzyme were found to be normal.
Efficacy of translation in the rickettsia Coxiella burnetii
Authors: Donahue J P , Thompson H A
Published: January 2020

The addition of coliphage Q beta ribonucleic acid to a cell-free translation system obtained from Coxiella burnetii cells caused the formation of monosomes and disomes from ribosomal subunits and resulted in synthesis of viral coat protein. Rickettsial ribosomes and associated translation factors functioned together, with fidelity, efficiency, and a specificity similar to those of free-living gram-negative bacteria.
Transformation of Streptococcus sanguis with monomeric pVA736 plasmid deoxyribonucleic acid
Authors: Macrina F L , Jones K R , Welch R A
Published: January 2020

Monomeric and oligomeric forms of a 5.0 x 10(6)-dalton plasmid (conferring erythromycin resistance) were able to genetically transform naturally competent Streptococcus sanguis. Transformation with electrophoretically purified monomer was a second-order process, whereas transformation with a dye-buoyant density gradient-purified plasmid preparation followed one-hit kinetics.
Regulation of methyl-beta-d-thiogalactopyranoside-6-phosphate accumulation in Streptococcus lactis by exclusion and expulsion mechanisms
Authors: Thompson J , Saier M H
Published: January 2020

Starved cells of Streptococcus lactis ML3 (grown previously on galactose, lactose, or maltose) accumulated methyl-beta-D-thiogalactopyranoside (TMG) by the lactose:phosphotransferase system. More than 98% of accumulated sugar was present as a phosphorylated derivative, TMG-6-phosphate (TMG-6P). When a phosphotransferase system sugar (glucose, mannose, 2-deoxyglucose, or lactose) was added to the medium simultaneously with TMG, the beta-galactoside was excluded from the cells. Galactose enhanced the accumulation of TMG-6P. Glucose, mannose, lactose, or maltose plus arginine, was added to a suspension of TMG-6P-loaded cells of S. lactis ML3, elicited rapid expulsion of intracellular solute. The material recovered in the medium was exclusively free TMG. Expulsion of galactoside required both entry and metabolism of an appropriate sugar, and intracellular dephosphorylation of TMG-6P preceded efflux of TMG. The rate of dephosphorylation of TMG-6P by permeabilized cells was increased two-to threefold by adenosine 5'-triphosphate but was strongly inhibited by fluoride. S. lactis ML3 (DGr) was derived from S. lactis ML3 by positive selection for resistance to 2-deoxy-D-glucose and was defective in the enzyme IIMan component of the glucose:phosphotransferase system. Neither glucose nor mannose excluded TMG from cells of S. lactic ML3 (DGr), and these two sugars failed to elicit TMG expulsion from preloaded cells of the mutant strain. Accumulation of TMG-6P by S. lactis ML3 can be regulation by two independent mechanisms whose activities promote exclusion or expulsion of galactoside from the cell.
Genetics of L-proline utilization in Escherichia coli
Authors: Wood J M
Published: January 2020

L-Azetidine-2-carboxylate (AC) and 3,4-dehydro-D,L-proline (DHP) are toxic L-proline analogs that can be used to select bacterial mutants defective for L-proline transport. Mutants resistant to AC and DHP are defective for proline transport alone (putP mutants), and mutants resistant to AC but not to DHP are defective both in putP and in the closely linked proline dehydrogenase gene putA. Proline dehydrogenase oxidizes DHP but not AC, probably detoxifying the former compound. These observations were exploited in preparing an otherwise isogenic set of Escherichia coli K-12 strains with well-defined defects in the putP and putA genes. The results of this study suggest that the genetic and biochemical characteristics of proline utilization in E. coli K-12 are closely analogous to those of Salmonella typhimurium.
Respiration-associated components of Mollicutes
Authors: Pollack J D , Merola A J , Platz M , Booth R L
Published: January 2020

No cytochrome pigments were detected by difference (reduced minus oxidized) spectroscopy at liquid nitrogen temperature in whole-cell preparations or membrane fractions of Acholeplasma axanthum S273, Acholeplasma equifetale N93, Acholeplasma granularum BTS39, Acholeplasma laidlawii B-PG9, Acholeplasma modicum PG-49, Acholeplasma oculi 19L, Mycoplasma arginini G230, Mycoplasma arthritidis 07, Mycoplasma pneumoniae FH, and Mycoplasma pulmonis JB. All ten Mollicutes species examined contained iron of unknown function (3.0 to 15.3 nmol of iron per mg of protein). Relatively small amounts of acid-labile sulfide were found in all fractions (0.10 to 1.07 nmol of acid-labile sulfide per mg of protein). The data suggest that, as Mollicutes lack cytochrome pigments, they would synthesize most if not all adenosine triphosphate at the substrate level.
Nitrosoguanidine sequential mutagenesis mapping of Mycobacterium tuberculosis genes
Authors: Woodley C L , Baldwin J N , Greenberg J
Published: January 2020

Nitrosoguanidine-induced mutations occur at higher frequencies at the replication region than at other nonreplicating regions of the chromosome. Cultures of Mycobacterium tuberculosis synchronized with phenylethanol were used to determine the order of replication for 10 genes controlling drug resistance. Use of M. tuberculosis provided a 10-h replication map with good resolution because of the slow rate of deoxyribonucleic acid replication. The direction of chromosome replication could not be determined, but this study indicated no pause between rounds of deoxyribonucleic acid replication in a rich medium.
Acetate kinase activity in mycoplasmas
Authors: Muhlrad A , Peleg I , Robertson J A , Robinson I M , Kahane I
Published: January 2020

Acetate kinase activity was assayed in 13 mycoplasmas. Nine species exhibited the enzymic activity in the direction of either synthesis of acetylphosphate or adenosine triphosphate. On the other hand Mycoplasma orale, Mycoplasma arthritidis, Ureaplasma urealyticum (10 serotypes), and two strains of Anaeroplasma species exhibited only minimal levels of the enzymic activity. In these four species, the enzyme does not seem to play a key role in adenosine triphosphate formation.
Isolation and characterization of several unique lipids from Azotobacter vinelandii cysts
Authors: Su C J , Reusch R N , Sadoff H L
Published: January 2020

Unique cyclic compounds were found in the lipid fraction of Azotobacter vinelandii cysts. In addition to two major molecular species which had already been identified, 5-n-alkylresorcinol and its galactoside derivative, five other molecular species (two alkyl side chain homologs of each) were isolated, and their structures were established by infrared, ultraviolet, nuclear magnetic resonance, and mass spectroscopy. These 10 compounds were 6-n-heneicosylresorcylic acid methyl ester and 6-n-tricosylresorcylic acid methyl ester, 5-n-(2-hydroxy)heneicosylresorcinol and 5-n-(2-hydroxy-tricosylresorcinol, 5-n-heneicosyl-4-acetylresorcinol and 5-n-tricosyl-4-acetylresorcinol, 6-n-heneicosyl-4-hydroxypyran-2-one and 6-n-tricosyl-4-hydroxypyran-2-one, and 6-(2-oxotricosyl)-4-hydroxy-pyran-2-one and 6-(2-oxopentacosyl)-4-hydroxypyran-2-one.
Relationship of Escherichia coli density to growth rate and cell age
Authors: Martínez-Salas E , Martín J A , Vicente M
Published: January 2020

The cell densities of Escherichia coli strains B/rA, BrF, and K-12 (OV-2) were measured at several growth rates and found to be very near 1.105 g/ml in all cases. Ninety percent of the cells of any exponentially growing population banded at densities differing less than 0.75% from the mean. Synchronized populations of B/rA selected as newborn cells were found to keep their density constant for longer than one generation time. However, if selection was based on cell size, by sedimentation through a sucrose gradient, cell density was found to be almost 2% lower than that of newborn cells, but it reached normal values before the first division had taken place. These results meant that mass and volume during the lifetime of the bacterial cell followed parallel kinetics. It was unlikely that density could regulate any event of the lifetime of a cell; on the contrary, density seemed to be a physical parameter that was well controlled during the bacterial growth.
Defective enzyme II-BGlc of the phosphoenolpyruvate:sugar phosphotransferase system leading to uncoupling of transport and phosphorylation in Salmonella typhimurium
Authors: Postma P W
Published: January 2020

Transport and phosphorylation of glucose via enzymes II-A/II-B and II-BGlc of the phosphoenolpyruvate:sugar phosphotransferase system are tightly coupled in Salmonella typhimurium. Mutant strains (pts) that lack the phosphorylating proteins of this system, enzyme I and HPr, are unable to transport or to grow on glucose. From ptsHI deletion strains of S. typhimurium, mutants were isolated that regained growth on and transport of glucose. Several lines of evidence suggest that these Glc+ mutants have an altered enzyme II-BGlc as follows. (i) Insertion of a ptsG::Tn10 mutation (resulting in a defective II-BGlc) abolished growth on and transport of glucose in these Glc+ strains. Introduction of a ptsM mutation, on the other hand, which abolishes II-A/II-B activity, had no effect. (ii) Methyl alpha-glucoside transport and phosphorylation (specific for II-BGlc) was lowered or absent in ptsH+,I+ transductants of these Glc+ strains. Transport and phosphorylation of other phosphoenolpyurate:sugar phosphotransferase system sugars were normal. (iii) Membranes isolated from these Glc+ mutants were unable to catalyze transphosphorylation of methyl alpha-glucoside by glucose 6-phosphate, but transphosphorylation of mannose by glucose 6-phosphate was normal. (iv) The mutation was in the ptsG gene or closely linked to it. We conclude that the altered enzyme II-BGlc has acquired the capacity to transport glucose in the absence of phosphoenolpyruvate:sugar phosphotransferase system-mediated phosphorylation. However, the affinity for glucose decreased at least 1,000-fold as compared to the wild-type strain. At the same time the mutated enzyme II-BGlc lost the ability to catalyze the phosphorylation of its substrates via IIIGlc.
Scanning electron probe x-ray microanalysis of elemental distributions in freeze-dried cryosections of Bacillus coagulans spores
Authors: Stewart M , Somlyo A P , Somlyo A V , Shuman H , Lindsay J A , Murrell W G
Published: January 2020

High-resolution scanning electron probe X-ray microanalysis had been employed to examine elemental distributions in freeze-dried cryosections of Bacillus coagulans spores. Calcium, manganese, and phosphorus were concentrated in the protoplast and the coat. Iron was found in the coat but not in the protoplast, whereas the silicon seen on the coat of other spore species was absent. Sulfur was present in the coat, but was distributed over a broader area than the other elements, which suggested that phosphorus and the metal ions were located in the outer coat layer.
Developmental cycle of Coxiella burnetii: structure and morphogenesis of vegetative and sporogenic differentiations
Authors: McCaul T F , Williams J C
Published: January 2020

Coxiella burnetii is a gram-variable obligate intracellular bacterium which carries out its development cycle in the phagolysosome of eucaryotic cells. Ultrastructural analysis of C. burnetii, in situ and after Renografin purification, by transmission electron microscopy of lead-stained thin sections has revealed extreme pleomorphism as demonstrated by two morphological cell types, a large cell variant (LCV) and a small cell variant (SCV). Potassium permanganate staining of purified rickettsiae revealed a number of differences in the internal structures of the cell variants. (i) The outer membrane of the sCV and LCV were comparable; however, the underlying dense layer of the SCV was much wider and more prominent than that of the LCV. The periplasmic space of the SCV was not readily visualized, whereas the periplasmic space of the LCV was apparent and resembled that of other gram-negative bacteria. (ii) Complex internal membranous intrusions which appeared to originate from the cytoplasmic membrane were observed in the SCV. The LCV did not harbor an extensive membranous system. (iii) Some LCVs contained a dense body in the periplasmic space. This endogenous structure appeared to arise in one pole of the LCV as an electrondense "cap" formation with the progressive development of a dense body approximately 130 to 170 nm in diameter which was eventually surrounded by a coat of at least four layers. Our observations suggest that the morphogenesis of C. burnetii is comparable, although not identical, to cellular differentiation of endospore formation. A developmental cycle consisting of vegetative and sporogenic differentiation is proposed.
Effects of Unsaturated Fatty Acids on the Morphogenesis of an Unsaturated Fatty Acid Auxotroph of
Escherichia coli
Authors: Kuriki Yoshitaka
Published: January 2020

Supplementation of linoleate or linolenate in a culture medium caused abnormal morphogenesis in an unsaturated fatty acid auxotroph of
Escherichia coli
K-12.
Biosynthesis of bacterial glycogen: activator specificity of the adenosine diphosphate glucose pyrophosphorylases from the genus Rhodospirillum
Authors: Preiss J , Greenberg E
Published: January 2020

The adenosine diphosphate (ADP) glucose pyrophosphorylases from Rhodospirillum fulvum, Rhodospirillum molischianum, and Rhodospirillum tenue were partially purified, and their kinetic properties were studied. The enzyme from the three organisms was found to be activated by pyruvate and thus was similar to the Rhodospirillum rubrum enzyme that had been previously studied (C. E. Furlong, and J. Preiss, J. Biol. Chem. 244:2539-2548, 1979). The enzymes from R. fulvum, R. molischianum, and R. tenue were also activated by oxamate, an analog of pyruvate. Other alpha-keto acids, alpha-ketobutyrate and hydroxypyruvate, activated to a smaller extent. The presence of pyruvate increased the apparent affinity for adenosine 5'-triphosphate and MgCl2 for all three enzymes. The R. molischianum enzyme has very little sensitivity to inhibition by adenosine 5'-monophosphate, ADP, or inorganic phosphate. However, R. tenue ADPglucose pyrophosphorylase is very sensitive to inhibition by adenosine 5'-monophosphate, and the R. fulvum enzyme is inhibited by ADP. Increasing pyruvate concentration reversed the inhibition caused by adenosine 5'-monophosphate or ADP. Since ADPglucose is the glycosyl donor for synthesis of glycogen, it is possible that in vivo glycogen synthesis is regulated by the concentration of pyruvate and, in the case of R. fulvum and R. tenue, by the ratio of pyruvate concentration to inhibitor concentration.
Escherichia coli gal operon proteins made after prophage lambda induction
Authors: Merril C R , Gottesman M E , Adhya S L
Published: January 2020

Expression of the EScherichia coli gal operon under the control of the prophage lambda promoter pL leads to gross discoordinacy of gal expression. Expression of the most promoter-distal cistron galK is much greater than expression of the promoter-proximal cistron galE. We had previously shown that transcription of the gal operon is coordinate after prophage induction. A survey of protein synthesized after prophage induction indicated that lack of expression of galE is due to a failure of translation of the galE sequence in the pL-gal transcript. This failure of translation of the galE sequence may be due to extensive dyad symmetry present in the vicinity of the gal promoter region of the pL-gal transcript. This symmetry could result in a ribonucleic acid stem-loop structure, blocking the attachment of ribosomes at the Shine-Dalgarno sequence of galE. To test this model, strains bearing the IS1 or IS2 insertion, deletion, or new promoter mutation within the symmetrical region were constructed. The restoration of some galE expression after such disruptions of the symmetrical region indicated that the ribonucleic acid stem-loop structure did play a role in the discoordinate expression of gal from pL. However, failure to obtain galE expression coordinated with high levels of galK expression suggested that other components were involved, perhaps other symmetries between galE and the pL transcript.
Tn10 insertions in the pfkB region of Escherichia coli
Authors: Daldal F , Fraenkel D G
Published: January 2020

The locus pfkB is known to determine expression of a minor phosphofructokinase (Pfk-2). Pfk-2 and pfkB seem to be dispensable, since Tn10 insertions in pfkB, as well as deletions from Tn10 nearby, are obtainable. Strains deleted for both pfkA and pgkB are unable to grow at all on sugars whose primary route of metabolism is via fructose 6-phosphate, confirming earlier reports implicating the low Pfk-2 activity, rather than the pentose-phosphate pathway, as needed for the slow growth on sugars of pfkA pfkB+ strains. The pfkB locus probably contains the structural gene for Pfk-2, since a mutation closely linked to pfkB1, which affects growth on glycerol, is found to alter the enzyme. Partial phenotypic suppression of the pfkA mutant phenotype results from Tn10 insertion very close to the pps gene, ca. 0.5 min from pgkB. The insertion does not clearly affect either Pfk-2 or phosphoenolpyruvate synthetase, and the mechanism of suppression is unclear.
Succinate transport in Rhizobium leguminosarum
Authors: Finan T M , Wood J M , Jordan D C
Published: January 2020

The transport of succinate was studied in an effective streptomycin-resistant strain of Rhizobium leguminosarum. High levels of succinate transport occurred when cells were grown on succinate, fumarate, or malate, whereas low activity was found when cells were grown on glucose, sucrose, arabinose, or pyruvate as the sole carbon source. Because of the rapid metabolism of succinate after transport into the cells, a succinate dehydrogenase-deficient mutant was isolated in which intracellular succinate accumulated to over 400 times the external concentration. Succinate transport was completely abolished in the presence of metabolic uncouplers but was relatively insensitive to sodium arsenate. Succinate transport was a saturable function of the succinate concentration, and the apparent Km and Vmax values for transport were determined in both the parent and the succinate dehydrogenase mutant. Malate and fumarate competitively inhibited succinate transport, whereas citrate and malonate had no effect. Succinate transport mutants were isolated by transposon (Tn5) mutagenesis. These mutants were unable to transport succinate or malate and were unable to grow on succinate, malate, or fumarate as the sole carbon source. The mutants grew normally on pyruvate, oxaloacetate, citrate, or arabinose, and revertants isolated on succinate minimal medium had regained the ability to grow on malate and fumarate. From these data, we conclude that R. leguminosarum possesses a C4-dicarboxylic acid transport system which is inducible and mediates the active transport of succinate, fumarate, and malate into the cell.
Levels of H+ and other monovalent cations in dormant and germinating spores of Bacillus megaterium
Authors: Swerdlow B M , Setlow B , Setlow P
Published: January 2020

Previous investigators using the extent of uptake of the weak base methylamine to measure internal pH have shown that the pH in the core region of dormant spores of Bacillus megaterium is 6.3 to 6.5. Elevation of the internal pH of spores by 1.6 U had no significant effect on their degree of dormancy or their heat or ultraviolet light resistance. Surprisingly, the rate of methylamine uptake into dormant spores was slow (time for half-maximal uptake, 2.5 h at 24 degrees C). Most of the methylamine taken up by dormant spores was rapidly (time for half-maximal uptake, less than 3 min) released during spore germination as the internal pH of spores rose to approximately 7.5. This rise in internal spore pH took place before dipicolinic acid release, was not abolished by inhibition of energy metabolism, and during germination at pH 8.0 was accompanied by a decrease in the pH of the germination medium. Also accompanying the rise in internal spore pH during germination was the release of greater than 80% of the spores K+ and Na+. The K+ was subsequently reabsorbed in an energy-dependent process. These data indicate (i) that between pH 6.2 and 7.8 internal spore pH has little effect on dormant spore properties, (ii) that there is a strong permeability barrier in dormant spores to movement of charged molecules and small uncharged molecules, and (iii) that extremely early in spore germination this permeability barrier is breached, allowing rapid release of internal monovalent cations (H+, Na+, and K+).
Wild-type isopropylmalate isomerase in Salmonella typhimurium is composed of two different subunits
Authors: Fultz P N , Kemper J
Published: January 2020

The isopropylmalate isomerase in Salmonella typhimurium is the second enzyme specific for leucine biosynthesis. It is a complex enzyme composed of two subunits which are coded for by two genes of the leucine operon, leuC and leuD. The two polypeptides have been shown to copurify through successive ammonium sulfate fractionations and have been identified on sodium dodecyl sulfate-polyacrylamide gels as having molecular weights of 51,000 (leuC gene product) and 23,500 (leuD gene product). They have also been shown to be fairly stable, since in vitro complementation of cell-free extracts of leuC and leuD mutant strains was demonstrated, with only a 40% loss of activity 16 h after preparation of the extracts. The native isopropylmalate isomerase was shown to have a Km for its substrate alpha-isopropylmalate of 3 x 10(-4)M.
Assembly of the adenosine triphosphatase complex in Escherichia coli: assembly of F0 is dependent on the formation of specific F1 subunits
Authors: Cox G B , Downie J A , Langman L , Senior A E , Ash G , Fayle D R , Gibson F
Published: January 2020

A strain of Escherichia coli (AN1007) carrying the polar uncD436 allele which affects the operon coding for the F1-F0 adenosine triphosphatase (ATPase) complex was isolated and characterized. The uncD436 allele affected the two genes most distal to the operon promoter, i.e., uncD and uncC. Although the genes coding for the F0 portion of the ATPase complex were not affected in strains carrying this mutant allele, the lack of reconstitution of washed membranes by normal F1 ATPase suggested that a functional F0 might not be formed. This conclusion was supported by the observation that the 18,000-molecular-weight F0 subunit, coded for by the uncF gene, was absent from the membranes. Plasmid pAN36 (uncD+C+), when inserted into a strain carrying the uncD436 allele, resulted in the incorporation of the 18,000-molecular-weight F0 subunit into the membrane. A further series of experiments with Mu-induced polarity mutants, with and without plasmid pAN36, showed that the formation of both the alpha- and beta-subunits of F1 ATPase was an essential prerequisite to the incorporation into the membrane of the 18,000-molecular-weight F0 subunit and to the formation of a functional F0. Examination of the polypeptide composition of membranes from various unc mutants allowed a sequence for the normal assembly of the F1-F0 ATPase complex to be proposed.
Pathway for D-galactonate catabolism in nonpathogenic mycobacteria
Authors: Szumiło T
Published: January 2020

D-Galactonate is catabolized in saprophytic mycobacteria to give pyruvate and glyceraldehyde-3-phosphate by a pathway that involves the sequential reactions of galactonate dehydratase, 2-keto-3-deoxy-galactonate kinase, and 6-phospho-2-keto-3-deoxy-galactonate aldolase.
Regulation of fatty acid degradation in Escherichia coli: analysis by operon fusion
Authors: Clark D
Published: January 2020

Fusion of the lacZ gene coding for beta-galactosidase to the fadA,B and fadE operons was accomplished by using the phage Mu d (Apr lac). In such fusion strains, beta-galactosidase was induced by long-chain fatty acids and repressed by glucose, as is the normal pattern of control for the enzymes of the fad regulon. The level of induction seen was approximately 10-fold for both the fadA and fadE operons. These results demonstrate that the previously observed regulation of both the fadA and fadE operons is at the transcriptional level. When an insertion mutation in the fadR (repressor) gene was introduced into the fusion strains, beta-galactosidase was produced constitutively. A series of fatty acids of different chain lengths were tested as inducers. Acids of chain lengths of 10 carbon atoms or less failed to induce, those of 12 carbon atoms induced partly, and those of 14 or more carbon atoms induced fully. Imidazole was found to counteract the glucose repression of the fadA operon as recently demonstrated for the ara operon.
Ferrisiderophore reductase activity associated with an aromatic biosynthetic enzyme complex in Bacillus subtilis
Authors: Gaines C G , Lodge J S , Arceneaux J E , Byers B R
Published: January 2020

The cytoplasmic fractions obtained from Bacillus subtilis strains W168 and WB2802 catalyzed reductive release of iron from the ferric chelate of 2,3-dihydroxybenzoic acid (ferri-DHB), the ferrisiderophore produced by B. subtilis. Ferrisiderophore reductase activity may insert iron into metabolism. This activity required a reductant (reduced nicotinamide adenine dinucleotide phosphate was preferred), was oxygen sensitive, and was stimulated by flavin mononucleotide plus certain divalent cations. The cytoplasmic fractions also reduced 2,6-dichlorophenolindophenol; this reaction was stimulated by flavin mononucleotide plus a divalent cation. Ferri-DHB and 2,6-dichlorophenolindophenol reductase activities were copurified by phosphocellulose and diethylaminoethyl-cellulose chromatography. Nondenaturing polyacrylamide gel electrophoresis of the purified material revealed that both ferri-DHB and 2,6-dichlorophenolindophenol reductase activities were located in a protein band at Rf 0.75. The chromatographic procedures purified a reductase known to be associated with two aromatic biosynthetic enzymes, chorismate synthase and dehydroquinate synthase. Therefore, a portion of the ferrisiderophore reductase activity in B. subtilis may be catalyzed by a reductase that also is essential for aromatic biosynthesis.
Proteolytically induced changes in the molecular form of the carbamyl phosphate synthetase-uracil-aspartate transcarbamylase complex coded for by the URA2 locus in Saccharomyces cerevisiae
Authors: Denis-Duphil M , Mathien-Shire Y , Hervé G
Published: January 2020

When a uracil-auxotrophic yeast strain is grown under uracil-limiting conditions, the aspartate transcarbamylase activity found in crude extracts shows a variation in sensitivity to feedback inhibition by uridine 5'-triphosphate. In this study we correlated this variation with changes in the molecular form of the carbamyl phosphate synthetase-uracil-aspartate transcarbamylase complex. Carbamyl phosphate synthetase-uracil (molecular weight, 240,000) and uridine 5'-triphosphate-insensitive aspartate transcarbamylase (molecular weight, 140,000) were present separately in extracts from cells collected in the early exponential phase; this was in contrast to the presence of a single high-molecular-weight form (molecular weight, about 900,000) bearing both activities in extracts from stationary-phase cells. The lack of sensitivity to uridine 5'-triphosphate by aspartate transcarbamylase was delayed by adding uridine 5'-triphosphate before cell disruption and was prevented completely by adding phenylmethylsulfonyl fluoride. Thus, this event was attributed to a transient serine protease activity detected only in early exponential-phase cell extracts. However, even in the presence of phenylmethylsulfonyl fluoride, a sucrose density gradient analysis in the absence of uridine 5'-triphosphate revealed a change in the aggregation state of the complex which might have occurred in vivo. None of these events was observed in extracts from cells that lacked protease B activity (strain HP232-2B).
Competitive Advantage Provided by Bacterial Motility in the Formation of Nodules by
Rhizobium meliloti
Authors: Ames Peter , Bergman Kostia
Published: January 2020

The effect of motility on the competitive success of
Rhizobium meliloti
in nodule production was investigated. A motile strain formed more nodules than expected when mixed at various unfavorable ratios with either flagellated or nonflagellated nonmotile derivatives. We conclude that motility confers a selective advantage on rhizobia when competing with nonmotile strains.
Transformation of Haemophilus influenzae by plasmid RSF0885
Authors: Notani N K , Setlow J K , McCarthy D , Clayton N L
Published: January 2020

Plasmid RSF0885, which conferred ampicillin resistance, transformed competent Haemophilus influenzae cells with low efficiency (maximum, less than 0.01%). As judged by competition experiments and uptake of radioactivity, plasmid RSF0885 deoxyribonucleic acid was taken up into competent H. influenzae cells several orders of magnitude less efficiently than H. influenzae chromosomal deoxyribonucleic acid. Plasmid RSF0885 transformed cells with even lower efficiency than could be accounted for by the low uptake. Transformation was not affected by rec-1 and rec-2 mutations in the recipient, and strains cured of the plasmid did not show increased transformation. Plasmid molecules cut once with a restriction enzyme that made blunt ends did not transform. Transformation was favored by the closed circular form of the plasmid.
Partial purification and characterization of the multiple molecular forms of staphylococcal clotting activity (coagulase)
Authors: Reeves M W , Drummond M C , Tager M
Published: January 2020

The clotting activity of Staphylococcus aureus strain 104 was purified 46,000-fold, but absolute purity was not achieved. Carbohydrate content of the purified material was not more than 5%. Elution of clotting activity from denaturing and nondenaturing polyacrylamide gels revealed the presence of four distinct molecular forms. Molecular weights of the forms were approximately 31,500, 34,800, 44,800, and 56,800 as determined by gel filtration in 8 M urea, by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis, and by calculation with determined values for the Stokes radius and sedimentation coefficient. Molecular weights determined on sodium dodecyl sulfate-urea gels were found to decrease as the gel concentration increased, suggesting that the amount of sodium dodecyl sulfate bound was less than normal. Estimated frictional ratios for the forms showed that they differ in shape from one another and that they are all highly asymmetrical. Each of the forms had an isoelectric point between pH 5.44 and 5.47 when focused in 6% polyacrylamide gels for 9 h; however, prolonged focusing altered the isoelectric point of the forms to within the range of pH 4.35 to 4.65. The multiple clotting forms were not artifacts of the purification procedure and did not appear to be products of the proteolytic degradation of a larger protein.
Regulation of coenzyme A biosynthesis
Authors: Jackowski S , Rock C O
Published: January 2020

Coenzyme A (CoA) and acyl carrier protein are two cofactors in fatty acid metabolism, and both possess a 4'-phosphopantetheine moiety that is metabolically derived from the vitamin pantothenate. We studied the regulation of the metabolic pathway that gives rise to these two cofactors in an Escherichia coli beta-alanine auxotroph, strain SJ16. Identification and quantitation of the intracellular and extracellular beta-alanine-derived metabolites from cells grown on increasing beta-alanine concentrations were performed. The intracellular content of acyl carrier protein was relatively insensitive to beta-alanine input, whereas the CoA content increased as a function of external beta-alanine concentration, reaching a maximum at 8 microM beta-alanine. Further increase in the beta-alanine concentration led to the excretion of pantothenate into the medium. Comparing the amount of pantothenate found outside the cell to the level of intracellular metabolites demonstrates that E. coli is capable of producing 15-fold more pantoic acid than is required to maintain the intracellular CoA content. Therefore, the supply of pantoic acid is not a limiting factor in CoA biosynthesis. Wild-type cells also excreted pantothenate into the medium, showing that the beta-alanine supply is also not rate limiting in CoA biogenesis. Taken together, the results point to pantothenate kinase as the primary enzymatic step that regulates the CoA content of E. coli.
Distribution of mannosamine and mannosaminuronic acid among cell walls of Bacillus species
Authors: Yoneyama T , Koike Y , Arakawa H , Yokoyama K , Sasaki Y , Kawamura T , Araki Y , Ito E , Takao S
Published: January 2020

The distribution of mannosamine, mannosaminuronic acid, and the enzymes responsible for the formation of these saccharides was studied in nine species (18 strains) of Bacillus. Whereas UDP-N-acetylglucosamine 2-epimerase activity was detected in all of the strains examined, UDP-N-acetylmannosamine dehydrogenase, as well as the activity incorporating N-acetylmannosaminuronic acid residues from UDP-N-acetylmannosaminuronic acid into polymer, was found only in four strains of B. megaterium and one strain each of B. subtilis and B. polymyxa. The cell walls prepared from the six above-named strains were shown to contain mannosaminuronic acid in amounts of 135 to 245 nmol/mg. In contrast, mannosamine had a wide distribution. The cell walls from two strains of B. cereus and one strain each of B. circulans, B. polymyxa, B. sphaericus, and B. cereus subsp. mycoides contained mannosamine in amounts of 370 to 470 nmol/mg. In addition, the cell walls from five strains of B. subtilis, two strains of B. megaterium, and one strain each of B. cereus. B. coagulans, and B. licheniformis also contained this amino sugar in amounts as small as 10 to 35 nmol/mg. On the basis of analytical data, it is suggested that the mannosamine present in small amounts may be a common constituent of linkage units between peptidoglycan and other cell wall components such as glycerol teichoic acid.
Peptidoglycan of Rhodopseudomonas viridis: partial lack of N-acetyl substitution of glucosamine
Authors: Schmelzer E , Weckesser J , Warth R , Mayer H
Published: January 2020

A lack of at least 70% of N-acetyl substitution of glucosamine in the glycan strands of the peptidoglycan from the gram-negative bacterium Rhodopseudomonas viridis is reported. A disaccharide, very likely GlcN beta(1 leads to 4) Mur, was observed in hydrolysates of the isolated peptidoglycan. The disaccharide was not observed when peptidoglycan was N-acetylated before hydrolysis. The peptidoglycan of R. viridis was resistant to lysozyme but became sensitive after N-acetylation with acetic anhydride. The disaccharide was found with peptidoglycan from all R. viridis strains investigated, as well as with R. sulfoviridis P1 and R. palustris strains, but not with peptidoglycan from R. gelatinosa, Rhodospirillum tenue, and Pseudomonas diminuta NCTC 8545.
Signal sequence of alkaline phosphatase of Escherichia coli
Authors: Inouye H , Barnes W , Beckwith J
Published: January 2020

The amino acid sequence of the signal sequence of phoA was determined by DNA sequencing by using the dideoxy chain termination technique (Sanger et al., Proc. Natl. Acad. Sci. U.S.A. 74:5463-5467, 1977). The template used was single-stranded DNA obtained from M13 on f1 phage derivatives carrying phoA, constructed by in vitro recombination. The results confirm the sequence of the first five amino acids determined by Sarthy et al. (J. Bacteriol. 139:932-939, 1979) and extend the sequence in the same reading frame into the amino terminal region of the mature alkaline phosphatase (Bradshaw et al., Proc. Natl. Acad. Sci. U.S.A., 78:3473-3477, 1981). As was predicted (Inouye and Beckwith, Proc. Natl. Acad. Sci. U.S.A. 74:1440-1444, 1977), the signal sequence was highly hydrophobic. The alteration of DNA sequence was identified for a promoter mutation that results in the expression of phoA independent of the positive control gene phoB and in insensitivity to high phosphate.
Physical mapping and cloning of bacteriophage T4 anti-restriction endonuclease gene
Authors: Dharmalingam K , Revel H R , Goldberg E B
Published: January 2020

We have proposed that the ability of T4 to produce non-glucosylated progeny after a single cycle of growth on a galU rglA rglB+ mutant of Escherichia coli is due to the initiation of the rglB+ function by a phage-coded, anti-restriction endonuclease protein. Based on this hypothesis, we screened T4 deletion mutants for failure to give a burst in this host. The absence of an arn gene in phage mutants lacking the 55.5- to 58.4-kilobase region is verified by their inability to protect secondary infecting non-glucosylated phage from rglB-controlled cleavage. A functional arn gene was cloned on plasmid pBR325, and the 0.8-kilobase insert DNA was shown to be homologous to the DNA missing in the arn deletion phage.
Isolation and partial characterization of membrane vesicles carrying markers of the membrane adhesion sites
Authors: Bayer M H , Costello G P , Bayer M E
Published: January 2020

At areas of adhesion between outer membrane (OM) and inner membrane (IM) in gram-negative bacteria, newly synthesized membrane constituents are inserted, and bacteriophage infection occurs. We describe here the isolation of these sites from cell membrane fractions of Salmonella anatum. Sucrose density gradients yielded membrane vesicles of the OM and IM; their mutual cross-contamination was low, as measured by 2-keto-3-deoxyoctonate and beta-NADH-oxidase activities. To mark the areas of lipopolysaccharide synthesis in the envelope (the adhesion sites), we infected S. anatum with phage epsilon 15, which causes a rapid change (conversion) in the cell's O-antigenic composition from serogroup E1 to E2; lipopolysaccharide of type E2 also serves as receptor for phage epsilon 34. We found that the fractions of intermediate density (Int. M) from briefly converted cells bound both phage epsilon 34 and E2-specific antibody. In the electron microscope, epsilon 34 was seen to have absorbed with a high degree of significance to the Int. M fraction of briefly converted cells, but not to the Int. M fraction of unconverted cells. Furthermore, the Int. M fractions of briefly converted cells coagglutinated anti-E2-coated Staphylococcus aureus, whereas the OM and IM fractions showed comparatively little agglutination. In addition, Int. M material exhibited elevated phospholipase A1 and A2 activities comparable to those of the OM fraction; the IM was essentially phospholipase free. Our data indicate that this membrane fractionation allows one to isolate from Int. M regions a variety of activities associated with adhesion sites.
Oversynthesis of elongation factors G and Tu in Escherichia coli
Authors: Zengel J M , Lindahl L
Published: January 2020

We induced the oversynthesis of elongation factors Tu and G by using multicopy plasmids carrying the structural genes for these proteins under the control of the lac operator-promoter. We found no evidence that accumulation of excess elongation factor Tu or G affects the expression of genes for ribosomal proteins or elongation factors.
A third DNA polymerase from Spiroplasma citri and two other spiroplasmas
Authors: Charron A , Castroviejo M , Bebear C , Latrille J , Bove J M
Published: January 2020

Recently, two DNA polymerases (ScA and ScB) were isolated and characterized from Spiroplasma citri. We now have found a third DNA polymerase (ScC) not only in S. citri but also in the serologically related honeybee spiroplasma BC3 and the unrelated flower spiroplasma BNR1. Enzyme ScC is N-ethylmaleimide (NEM) sensitive. The three DNA polymerases from the honeybee spiroplasma seem to be similar to the respective enzymes of S. citri. However, whereas the NEM-resistant enzyme ScA from S. citri and that from the BC3 honeybee spiroplasma are retained on DEAE-cellulose and require 0.09 M KCl for elution, the NEM-resistant enzyme A from the flower spiroplasma BNR1 is not retained.
Stimulation of groE synthesis in Escherichia coli by bacteriophage lambda infection
Authors: Kochan J , Murialdo H
Published: January 2020

We found that infection of Escherichia cell by lambda results in at least a twofold stimulation in the rate of synthesis of one of the products of groE. To determine what lambda-coded factors were responsible for this stimulation, numerous phage lambda mutants carrying bio substitutions were analyzed for their ability to stimulate groE synthesis. Our results revealed that the main factor(s) which is responsible for stimulating groE synthesis is located between the endpoints of the lambda bio69 and lambda bio252 substitutions, a region of DNA coding for bet, gam, kil, and cIII.