bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Ethylenediaminetetraacetate upon the Surface of
Escherichia coli
Authors: Bayer Manfred E. , Leive Loretta
Published: January 2020

The effect of ethylenediaminetetraacetate (EDTA) on the envelope of two strains of
Escherichia coli
(B and Cla) was studied with freeze-fracturing methods. Untreated cells showed the outer membrane's outer surface with a fine texture of randomly spaced depressions of about 4.5-nm diameter; small areas with symmetrical arrangements of structural surface elements were also observed. The outer membrane's fracture plane revealed a random distribution of particles on its “concave” plane, only occasionally interrupted by particle-free areas. The “convex” aspect of the outer membrane's fracture plane showed only a few scattered particles. The cleavage plane of the inner membrane was often interrupted by many localized elevated plateaus, at which the cleaving process had, for short distances, switched to the outer membrane. The effects of EDTA treatment were mainly seen in the structure of the freeze-etched outer membrane: (i) the pits as well as the symmetrical surface elements of the outer membrane's outer surface had disappeared; (ii) a number of plateaus (about 20 to 50/cell) were seen at which a cleavage plane within the inner membrane had switched to the hydrophobic portion of the outer membrane (outer membrane's fracture plane). These plateaus were also visible in untreated cells; however, EDTA treatment apparently caused an increased exposure of plateaus. Surface areas, exposed by freeze-etching, revealed the underlying plateaus as elevations in the surface contour of the cell, suggesting a slower etching rate in the zones of the plateaus relative to the rest of the outer membrane. Well-defined, particle-free patches in the outer membrane's fracture plane, concave, were more frequent and larger in size after EDTA treatment than in the controls. In the presence of glycerol, the cells often cleaved in the outer membrane's fracture plane, but isolated plateaus were rarely observed. After metabolic poisoning of cells for 15 to 25 min at 37°C, the plateaus had widened. These data suggest that the material of the plateaus has a slow rate of lateral diffusion. Placement of EDTA-treated cells in fresh medium at 37°C caused, after 3 to 5 min, the reoccurrence of the pitted surface structure. We propose that the plateaus represent localized zones, at which newly synthesized lipopolysaccharide has been inserted.
Regulation of L-cystine transport in Salmonella typhimurium
Authors: Baptist E W , Kredich N M
Published: January 2020

A kinetic analysis of L-cystine uptake in wild-type Salmonella typhimurium indicates the presence of at least two, and possibly three, separate transport systems. CTS-1 accounts for the majority of uptake at 20 muM L-cystine, with a Vmax of 9.5 nmol/min per mg and a Km of 2.0 muM; CTS-2 is a low-capacity, higher-affinity system with a Vmax of 0.22 nmol/min per mg and a Km of 0.05 muM; a third, nonsaturable process has been designated CTS-3. We find that wild-type CTS-1 levels are at least 11 times higher in sulfur-limited cells than in L-cystine-grown cells. Pleiotropic cysteine auxotrophs of the types cysE (lacking serine transacetylase) and cysB- (lacking a regulatory element of positive control) have very low levels of CTS-1 even when grown under conditions of sulfur limitation, which response is analogous to that previously observed for cysteine biosynthetic enzymes (N . M. Kredich, J. Biol. Chem. 246:3474-3484, 1971). CTS-1 is induced in cysE mutants by growth in the presence of O-acetyl-L-serine (the product of serine transacetylase), again paralleling the behavior of the cysteine biosynthetic pathway. Strain DW25, a prototrophic cysBc mutant, which is constitutive for cysteine biosynthesis, is also derepressed for CTS-1 when grown on L-cystine. Since CTS-1 is regulated by sulfur limitation, O-acetyl-L-serine, and the cysB gene product, the same three conditions controlling cysteine biosynthesis, we propose that this transport system is a part of the cysteine regulon.
Effect of transient lambda prophage induction on ultraviolet light resistance and recombination in Escherichia coli
Authors: Braun A , Gluck D
Published: January 2020

Transient induction of lambda prophage increases the ultraviolet light resistance of most exponentially growing Escherichia coli lysogens. Resistance is increased in wild-type, recB, recB recC, recB recC recF, and recB recC recL hosts. No enhancement in recA lysogens was found, nor was there enhancement in stationary cultures. Enhancement was dependent upon the lambdared recombination system. Transient induction also increases the genetic recombination rate in recB lysogens as measured in Hfr X F- matings.
Morphological analysis of the division cycle of two Escherichia coli substrains during slow growth
Authors: Woldringh C L , de Jong M A , van den Berg W , Koppes L
Published: January 2020

Morphological parameters of the cell division cycle have been examined in Escherichia coli B/r A and K. Whereas the shape factor (length of newborn cell/width) of the two strains was the same at rapid growth (doubling time, tau, less than 60 min), with decreasing growth rate the dimensions of the two strains did change so that B/r A cells became more rounded and B/r K cells became more elongated. The process of visible cell constriction (T period) lasted longer in B/r A than in B/r K during slow growth, reaching at tau = 200 min values of 40 and 17 min, respectively. The time between termination of chromosome replication and cell division (D period) was found to be longer in B/r A than in B/r K. As a result, in either strain completion of chromosome replication seemed always to occur before initiation of cell constriction. Nucleoplasmic separation did not coincide with termination as during rapid growth but occurred in both strains within the T period, about 10 min before cell division.
Stalkless mutants of Caulobacter crescentus
Authors: Fukuda A , Iba H , Okada Y
Published: January 2020

A stalk, a single falgellum, several pili, and deoxyribonucleic acid (DNA) phage receptors are polar surface structures expressed at a defined time in the Caulobacter crescentus cell cycle. When mutants were isolated as DNA phage phiCbK-resistant or ribonucleic acid (RNA) phage phiCp2-resistant, as well as nonmotile, strains, 5 out of 30 such mutant isolates were found not to possess stalks, but did possess inactive flagella. These stalkless mutants were resistant simultaneously to both DNA and RNA phages and did not possess pili and DNA pendent stalkless mutants. All motile revertants simultaneously regained the capacity to form stalks and susceptibility to DNA and RNA phages. It is suggested that a single mutation pleiotropically affects stalk formation, flagella motility, and coordinate polar morphogenesis of pili and DNA phage receptors. The stalkless mutants grew at a generation time similar to that of the wild-type strain at 30 degrees C. Cell size and morphology of a stalkless mutant, C. crescentus CB13 pdr-819, were also similar to those of the wild-type strain, except for the absence of a stalk. In addition, the CB13 pdr-819 predivisional cells were partitioned into smaller and larger portions, indicating asymmetrical cell division, as in the wild-type strain. From these results, it is suggested that swarmer cells undergo transition to cells of a stalked-cell nature without stalk formation and that the cell cycle of the stalkless mutant proceeds in an ordered sequence similar to that defining the wild-type cell cycle.
Coordinate regulation by iron of the synthesis of phenolate compounds and three outer membrane proteins in Escherichia coli
Authors: McIntosh M A , Earhart C F
Published: January 2020

The biosynthesis of the low-molecular-weight iron carrier enterochelin and of three outer membrane polypeptides appears to be coordinately regulated by the amount of cell-associated iron in Escherichia coli K-12. Measurements of iron acquisition made throughout the growth cycle in iron-deficient media indicate that a very rapid accumulation of iron occurs in the first 2 h of growth; there is comparatively little iron uptake during exponential growth, which results in a gradual decrease in the cellular iron content with each generation. When this level falls below 400 ng of iron per mg (dry weight) of cells, there is a simultaneous onset of synthesis of the three outer membrane polypeptides and of enterochelin. This coordinate regulation was also observed in cells able to transport iron actively using only citrate as an iron-carrier.
Function of S-adenosylmethionine in germinating yeast ascospores
Authors: Choih S J , Ferro A J , Shapiro S K
Published: January 2020

Germination and outgrowth of ascospores of Saccharomyces cerevisiae 4579 require both methionine and adenine, whereas leucine is only required for outgrowth. The methionine requirement may be satisfied by S-adenosylmethionine, but this sulfonium compound will not substitute for adenine. Between 30 and 70 min of protein synthesis is initially required for the completion of germination in strain 4579. The inhibition of S-adenosylmethionine synthetase by trifluoromethionine prevents both germination and protein synthesis. During the initial stages of germination, the S-adenosylmethionine synthetase, S-adenosylmethionine decarboxylase, and transfer ribonucleic acid methyltransferases increased significantly, indicating that polyamines and/or the methylation of transfer ribonucleic acid are required for the initiation of germination.
Oxalate, formate, formamide, and methanol metabolism in Thiobacillus novellus
Authors: Chandra T S , Shethna Y I
Published: January 2020

Thiobacillus novellus was able to grow with oxalate, formate, formamide, and methanol as sole sources of carbon and energy. Extensive growth on methanol required yeast extract or vitamins. Glyoxylate carboligase was detected in extracts of oxalate-grown cells. Ribulose bisphosphate carboxylase was found in extracts of cells grown on formate, formamide, and thiosulfate. These data indicate that oxalate is utilized heterotrophically in the glycerate pathway, and formate and formamide are utilized autotrophically in the ribulose bisphosphate pathway. Nicotinamide adenine dinucleotide-linked formate dehydrogenase was present in extracts of oxalate-, formate-, formamide-, and methanol-grown cells but was absent in thiosulfate- and acetate-grown cells.
Molecular characterization of two beta-lactamase-specifying plasmids isolated from Neisseria gonorrhoeae
Authors: Roberts M , Elwell L P , Falkow S
Published: January 2020

The molecular nature of two distinct gonococcal R plasmids, 4.4 X 10(6) and 3.2 X 10(6) daltons, encoding beta-lactamase activity were examined. Both plasmids contained about 40% of the transposable ampicillin resistance sequence Tn2. Deoxyribonucleic acid-deoxyribonucleic acid polynucleotide sequence studies have shown that the two gonococcal plasmids share about 70% of their sequences and are closely related to RSF0885, a 4.1 X 10(6)-dalton plasmid found in a beta-lactamase-producing strain of Haemophilus influenzae. All three of these R plasmids possess a guanine-plus-cytosine content of 0.40 to 0.41 mol fraction and are present as multicopy gene pools in their bacterial hosts.
Regulation of the arginine dihydrolase pathway in Clostridium sporogenes
Authors: Venugopal V , Nadkarni G B
Published: January 2020

Arginine deiminase activity was induced during the vegetative growth of Clostridium sporogenes. The enzyme was sensitive to catabolite repression. The other enzymes of the arginine dihydrolase pathway, namely, ornithine carbamoyl-transferase and carbamate kinase, did not show such variation.
Role of cyclic adenosine 3',5'-monophosphate on cessation of respiration in ultraviolet-irradiated Escherichia coli
Authors: Swenson P A , Schenley R L , Joshi J G
Published: January 2020

The addition of cyclic adenosine 3',5'-monophosphate (cAMP) to ultraviolet-irradiated Escherichia coli B/r cultures causes additional cells to cease respiring and to die. These effects of cAMP are greater on glucose-grown cells, where the effects of ultraviolet radiations alone are smaller and where the intracellular concentrations of cAMP are known to be lower.
Inhibition of thiamine transport in Saccharomyces cerevisiae by thiamine disulfides
Authors: Iwashima A , Wakabayashi Y , Nose Y
Published: January 2020

Both thiamine disulfide and O-benzoyl thiamine disulfide, which are thiolfrom derivatives of thiamine, strongly inhibited thiamine transport in Saccharomyces cerevisiae. The inhibition appeared to be due to a high affinity of the analogs for yeast cell membranes, in which thiamine transport component(s) may be integrated.
Purification and properties of beta-lactamase from Proteus morganii
Authors: Fujii-Kuriyama Y , Yamamoto M , Sugawara S
Published: January 2020

The cephalosporin beta-lactamase was purified from a strain of Proteus morganii that showed resistance to beta-lactam antibiotics and produced the enzyme constitutively. The purified enzyme preparation gave a single protein band on polyacrylamide gel electrophoresis and consisted of a single polypeptide of molecular weight 38,000 to 40,000 from gel filtration of Sephadex G-100 and sodium dodecyl sulfate-acrylamide gel electrophoresis, its isoelectric point being pH 7.2 No cysteine residue was found in its amino acid composition. The specific activity was 190 mumol/min per mg of the purified enzyme protein for the hydrolysis of cephaloridine, the optimal pH was about 8.5 and the optimal temperature was 50 degrees C. Antibodies against the purified beta-lactamase inhibited not only the enzyme activity of the purified preparation, but also the enzyme activity of all of the other strains of P. morganii so far tested, regardless of whether the modes of their production were inducible or constitutive. None of the beta-lactamases produced by beta-lactam antibiotic-resistant strains of other species of Proteus was affected at all by the antibodies, thus showing that the purified cephalosporin beta-lactamase was of the species-specific type. The enzymological properties of the preparation have been compared with those of beta-lactamases derived from other gram-negative enteric bacteria.
Killer double-stranded ribonucleic acid synthesis in cell division cycle mutants of Saccharomyces cerevisiae
Authors: Shalitin C , Weiser I
Published: January 2020

The synthesis of killer double-stranded ribonucleic acid (dsRNA) in Saccharomyces cerevisiae was examined in seven different cell division cycle mutants (cdc) that are defective in nuclear deoxyribonucleic acid replication and contain the "killer character." In cdc28, cdc4, and cdc7, which are defective in the initiation of nuclear deoxyribonucleic acid synthesis, and in cdc23 or in cdc14, defective in medial or late nuclear division, an overproduction of dsRNA at the restrictive temperature was observed. In contrast to the above mutants, the synthesis of killer dsRNA is not enhanced at the restrictive temperature in either cdc8 or cdc21, which are defective in deoxyribonucleic acid chain elongation. Examination of killer sensitive strains (cdc7 K- and cdc4 K-) has shown that the complete killer dsRNA genome is essential for the overproduction of dsRNA at the restrictive temperature.
Isolation, genetic analysis, and characterization of Escherichia coli mutants with defects in the lacY gene
Authors: Hobson A C , Gho D , Müller-Hill B
Published: January 2020

Five hundred thirty-five lacY mutants were isolated from an Escherichia coli strain carrying the lactose operon on an F' factor, either without mutagenesis or after mutagenesis with 2-aminopurine or N-methyl-N'-nitro-N-nitrosoguanidine. Crosses against 48 independently isolated deletions ending in the lacY gene divided the gene into 36 deletion groups. Suppressibility studies with 7 nonsense suppressor strains classified 276 mutants as nonsense mutants and 78 as missense (or nonsuppressible) mutants. One hundred seventy-nine mutants were "leaky" and could not be so allocated, and two were found to have small internal deletions. Nonsense mutants could in many cases be subdivided even within deletion groups on the basis of their suppressibility pattern, giving a total of 70 groups of nonsense mutants. Studies of these mutants allow the following conclusions: lactose and melibiose most probably do not have separate binding sites on the permease; the lacY region most likely consists of one cistron, and so both active transport and facilitated diffusion are functions of one protein; and finally, there is probably no small defined region of the permease responsible for energy coupling of transport. Furthermore, the strains and the analysis form the basis for a future functional study of the permease by biochemical techniques.
Physiological Effects of Growth of an
Escherichia coli
Temperature-Sensitive
dnaZ
Mutant at Nonpermissive Temperatures
Authors: Chu Herman , Malone Margaret M. , Haldenwang William G. , Walker James R.
Published: January 2020

The physiological effects of incubation at nonpermissive temperatures of
Escherichia coli
mutants that carry a temperature-sensitive
dnaZ
allele [
dnaZ
(Ts)
2016
] were examined. The temperature at which the
dnaZ
(Ts) protein becomes inactivated in vivo was investigated by measurements of deoxyribonucleic acid (DNA) synthesis at temperatures intermediate between permissive and nonpermissive. DNA synthesis inhibition was reversible by reducing the temperature of cultures from 42 to 30°C; DNA synthesis resumed immediately after temperature reduction and occurred even in the presence of chloramphenicol. Inasmuch as DNA synthesis could be resumed in the absence of protein synthesis, we concluded that the protein product of the
dnaZ
allele (Ts)
2016
is renaturable. Cell division, also inhibited by 42°C incubation, resumed after temperature reduction, but the length of time required for resumption depended on the duration of the period at 42°C. Replicative synthesis of cellular DNA, examined in vitro in toluene-permeabilized cells, was temperature sensitive. Excision repair of ultraviolet light-induced DNA lesions was partially inhibited in
dnaZ
(Ts) cells at 42°C. The
dnaZ
+
product participated in the synthesis of both Okazaki piece (8–12
S
) and high-molecular-weight DNA. During incubation of
dnaZ
(Ts)(λ) lysogens at 42°C, prophage induction occurred, and progeny phage were produced during subsequent incubation at 30°C. The temperature sensitivity of both DNA synthesis and cell division in the
dnaZ
(Ts)
2016
mutant was suppressed by high concentrations of sucrose, lactose, or NaCl. Incubation at 42°C was neither mutagenic nor antimutagenic for the
dnaZ
(Ts) mutant.
Intracellular Distribution of Enzymes of Phospholipid Metabolism in Several Gram-Negative Bacteria
Authors: Dutt Anuradha , Dowhan William
Published: January 2020

Cell-free extracts of
Salmonella typhimurium, Serratia marcescens, Enterobacter aerogenes
, and
Micrococcus cerificans
contained the following enzymatic activities related to phospholipid metabolism: cytidine 5′-diphospho-1,2-diacyl-
sn
-glycerol (CDP-diglyceride):
l
-serine
O
-phosphatidyltransferase (phosphatidylserine synthase), phosphatidylserine decarboxylase, CDP-diglyceride:
sn
-glycero-3-phosphate phosphatidyltransferase (phosphatidylglycerophosphate synthase), phosphatidylglycerophosphate phosphatase, and CDP-diglyceride hydrolase. The intracellular distribution of these enzymatic activities as determined by sucrose density gradient centrifugation of cell-free extracts was shown to be similar in each species investigated. The phosphatidylserine decarboxylase, phosphatidylglycerophosphate synthase, and CDP-diglyceride hydrolase activities were all associated with the cell envelope fraction, whereas the phosphatidylserine synthase activity was associated mainly with the ribosomal fraction. These enzymatic activities are comparable and have an intracellular distribution similar to those found in
Escherichia coli
cell-free extracts. Therefore, the pathways established for phospholipid biosynthesis in
E. coli
can also account for the synthesis of the major phospholipids (phosphatidylethanolamine and phosphatidylglycerol) in several other gram-negative organisms. In addition, the unusual ribosomal association of the phosphatidylserine synthase from
E. coli
(Raetz and Kennedy, J. Biol. Chem.
247:
2008–2014, 1972) appears to be a general property for this activity in several other bacterial species.
Purification and characterization of the membrane-bound ferrochelatase from Spirillum itersonii
Authors: Dailey H A
Published: January 2020

The membrane-bound enzyme ferrochelatase (protoheme ferro-lyase, EC 4.99.1.1) was purified from isolated membrane fragments of Spirillum itersonii approximately 490-fold. Purification was achieved by solubilization with chaotropic salts followed by ammonium sulfate fractionation, diethylaminoethyl-cellulose chromatography, and gel filtration on Sephadex G-200. The purified enzyme has an apparent minimum molecular weight of approximately 50,000, as determined by gel filtration in the presence of 0.1% Brij 35 and 1 mM dithiothreitol but forms high-molecular-weight aggregates in the absence of detergent. Purified ferrochelatase is strongly stimulated in the presence of copper. The apparent Km for Fe2+ is 20 micrometer in the absence of copper and 9.5 micrometer in the presence of 20 micrometer CuCl2. The apparent Km for protoporphyrin is 50 micrometer, and it is unaltered by copper. Ferrochelatase has a single pH optimum of 7.50, and it is inhibited 50% by 20 micrometer heme. Certain divalent cations and sulfhydryl reagents also inhibit the enzyme.
Amino acid replacement in a mutant lipoprotein of the Escherichia coli outer membrane
Authors: Inouye S , Lee N , Inouye M , Wu H C , Suzuki H , Nishimura Y , Iketani H , Hirota Y
Published: January 2020

The primary structure of a mutant lipoprotein of the outer membrane of Escherichia coli was investigated. This mutant was previously described as a mutant that forms a dimer of the lipoprotein by an S-S bridge (H. Suzuki et al., J. Bacteriol. 127:1494-1501, 1976). The amino acid analysis of the mutant lipoprotein revealed that the mutant lipoprotein had an extra cysteine residue, with concomitant loss of an arginine residue. From the analysis of the mutant lipoprotein revealed that the mutant lipoprotein had an extra cysteine residue, with concomitant loss of an arginine residue. From the analysis of tryptic peptides, it was found that the arginine residue at position 57 was replaced with a cysteine residue. The amino terminal structure of the mutant lipoprotein was found to be glycerylcysteine, as in the case of the wild-type lipoprotein. The present results show that the mutation that was previously determined to map at 36.5 min on the E. coli chromosome occurred in the structure gene (lpp) for the lipoprotein. This was further confirmed by the fact that a merodiploid carrying both lpp+ and lpp produces not only the wild-type lipoprotein but also the mutant lipoprotein.
Properties of
Escherichia coli
Mutants Deficient in Enzymes of Glycolysis
Authors: Irani Meher H. , Maitra P. K.
Published: January 2020

Physiological properties of mutants of
Escherichia coli
defective in glyceraldehyde 3-phosphate dehydrogenase, glycerate 3-phosphate kinase, or enolase are described. Introduction of a lesion in any one of the reversible steps catalyzed by these enzymes impaired both the glycolytic and gluconeogenic capabilities of the cell and generated an obligatory requirement for a source of carbon above the block (gluconeogenic) and one below (oxidative). A mixture of glycerol and succinate supported the growth of these mutants. Mutants lacking glyceraldehyde 3-phosphate dehydrogenase and glycerate 3-phosphate kinase could grow also on glycerol and glyceric acid, and enolase mutants could grow on glycerate and succinate, whereas double mutants lacking the kinase and enolase required
l
-serine in addition to glycerol and succinate. Titration of cell yield with limiting amounts of glycerol with Casamino Acids in excess, or vice versa, showed the gluconeogenic requirement of a growing culture of
E. coli
to be one-twentieth of its total catabolic and anabolic needs. Sugars and their derivatives inhibited growth of these mutants on otherwise permissive media. The mutants accumulated glycolytic intermediates above the blocked enzyme on addition of glucose or glycerol to resting cultures. Glucose inhibited growth and induced lysis. These effects could be substantially overcome by increasing the osmotic strength of the growth medium and, in addition, including 5 mM cyclic adenosine 3′,5′-monophosphate therein. This substance countered to a large extent the severe repression of β-galactosidase synthesis that glucose caused in these mutants.
Bacillus subtilis mutant with temperature-sensitive net synthesis of phosphatidylethanolamine
Authors: Lindgren V , Holmgren E , Rutberg L
Published: January 2020

Bacillus subtilis mutants with temperature-sensitive growth on complex media were screened for defects in phospholipid metabolism. One mutant was isolated that showed temperature-sensitive net synthesis of phosphatidylethanolamine. The mutant did not accumulate phosphatidylserine at the nonpermissive temperature. In the presence of hydroxylamine, wild-type B. subtilis accumulated phosphatidylserine at both 32 and 45 degrees C, whereas the mutant did only at 32 degrees C. In vitro phosphatidylethanolamine synthesis with bacterial membranes is no more temperature sensitive with mutant membranes than with wild-type membranes. The mutation probably affects the synthesis indirectly, possibly by altering a membrane protein. The mutant bacteria grew at the nonpermissive temperature, 45 degrees C, in a phosphate buffer-based minimal medium, although net synthesis of phosphatidylethanolamine was also temperature sensitive in this medium. One mutation caused both temperature-sensitive growth on complex media and temperature-sensitive net synthesis of phosphatidylethanolamine. The mutation is linked to aroD by transformation.
Glucose transport in Streptococcus agalactiae and its inhibition by lactoperoxidase-thiocyanate-hydrogen peroxide
Authors: Mickelson M N
Published: January 2020

Transport of 2-deoxyglucose or glucose in Streptococcus agalactiae was strongly inhibited if the cells were first exposed to a combination of lactoperoxidase-thiocyanate-hydrogen peroxide (LP-complex). The inhibition was completely reversible with dithiothreitol. N-ethylmaleimide and p-chloromercuribenzoate inhibited sugar transport, and the inhibition was also reversible with dithiothreitol. Sodium fluoride also inhibited sugar transport. Glucolysis was completely inhibited, and dithiothreitol completely reversed the inhibition. Phosphoenolpyruvate-dependent phosphotransferase activity in S. agalactiae was not strongly inhibited by the LP-complex. Interference of the entry of glucose into cells of S. agalactiae by the LP-complex could well account for its growth inhibitory properties with this organism. The inhibition of glucose transport by the LP-complex and its reversibility with dithiothreitol suggest the modification of functional sulfhydryl groups in the cell membrane as a cause of transport inhibition.
Transformation in pneumococcus: existence and properties of a complex involving donor deoxyribonucleate single strands in eclipse
Authors: Morrison D A
Published: January 2020

Donor deoxyribonucleic acid (DNA) single strands exist in a complex during the eclipse phase in pneumococcal transformation. This eclipse complex exhibited specific physical properties distinct from those of both pure DNA single strands and native DNA. These included a lower affinity for diethylaminoethyl-cellulose and hydroxylapatite than that of single-strand DNA, faster sedimentation than the DNA chains that it contains, and a buoyant density in Cs2SO4 lower than that of native DNA. The complex was dissociated by treatments with sodium dodecyl sulfate, NaOH, guanidine-hydrochloride, chloroform, and proteinase K but was insensitive to ribonuclease.
Ferredoxin and Formyltetrahydrofolate Synthetase: Comparative Studies withClostridium acidiurici, Clostridium cylindrosporum, and Newly Isolated Anaerobic Uric Acid-Fermenting Strains
Authors: Champion Alexander B. , Rabinowitz Jesse C.
Published: January 2020

Six strains ofClostridium acidiuriciand three strains ofC. cylindrosporumwere isolated from soil samples by enrichment culture with uric acid as the source of carbon, nitrogen, and energy. The newly isolated strains were characterized by their spore morphology and the amounts of glycine and formate formed by the fermentation of uric acid. The strains were easily identified as belonging to one species or the other on the basis of spore morphology and formate production. The crystal properties and spectra of the native ferredoxins of all the strains isolated and the amino acid composition and partial carboxy-terminal sequence of all their apoferredoxins were determined. All the ferredoxins were tested for cross-reactivity with antiserum toC. acidiuriciferredoxin by microcomplement fixation. Five of the sixC. acidiuricistrains, which had ferredoxins with amino acid compositions identical to that fromC. acidiurici, also showed immunological identity (immunological distance = 0.0). These results suggest sequence identity. The one strain with a different amino acid composition failed to show complete cross-reactivity. Two of the threeC. cylindrosporumstrains have ferredoxin amino acid compositions identical to that fromC. cylindrosporum. The third strain had a minimum of five differences in sequence. AllC. cylindrosporumstrains had ferredoxins that differed considerably fromC. acidiuricistrains (minimum of eight to nine differences), and none of these ferredoxins cross-reacted with antisera toC. acidiuriciferredoxin. Antisera were prepared to formyltetrahydrofolate synthetase fromC. acidiuriciandC. cylindrosporum, and all possible comparisons were made by using immunodiffusion and microcomplement fixation. There is more intraspecies variation in the synthetases than in the ferredoxins; however, the results suggest considerable interspecies differences in both proteins. These results suggest a low degree of genomic relatedness between the two species, which contrasts sharply with their apparent high degree of phenotypic similarity.
Isolation of a lambdadcys transducing bacteriophage and its use in determining the regulation of cysteine messenger ribonucleic acid synthesis in Escherichia coli K-12
Authors: Fimmel A L , Loughlin R E
Published: January 2020

A defective specialized lambda transducing phage carrying the cysJ, cysI, cysH, and cysD genes has been isolated from a secondary-site lysogen. Deoxyribonucleic acid-ribonucleic acid (DNA-RNA) hybridization studies utilizing this phage have been carried out to detect cysteine-specific messenger RNA (cys mRNA) synthesized in vivo. A vivo. A 3.5- to 9-fold increase in the rate of synthesis of cys mRNA has been detected in the derepressed wild-type (Cys+) strain grown on glutathione compared with a repressed control grown on cystine. Pleiotropic cysE and cysB mutants grown on glutathione were found to possess rates of synthesis of cys mRNA that were significantly lower than their derepressed isogenic parent. The addition of O-acetyl-L-serine to the cysE strain produced a 5.5-fold increase in the rate of synthesis of cys mRNA. These results indicate that cysteine biosynthesis is controlled at the level of transcription by the inducer O-acetylserine, the cysB protein and cyst(e)ine.
Genetic mapping of the F plasmid gene that promotes degradation of stable ribonucleic acid in Escherichia coli
Authors: Ohnishi Y , Iguma H , Ono T , Nagaishi H , Clark A J
Published: January 2020

F+ Escherichi coli cells that contain an srnA mutant allele degrade their stable ribonucleic acid (RNA) extensively after RNA synthesis is blocked at 42 degrees C. The relevant gene promoting degradation of stable RNA, srnB+, or its promoter was mapped between 1.7 and 2.8 kilobases on the F plasmid by using deleted F' plasmids and chimeric plasmids composed of pSC101 and fragments of F plasmid.
Osmotic imbalance in inositol-starved spheroplasts of Saccharomyces cerevisiae
Authors: Atkinson K D , Kolat A I , Henry S A
Published: January 2020

Physiological states associated with inositol starvation of spheroplasts of Saccharomyces cerevisiae were investigated and compared with conditions preceding death of starved whole cells. In the absence of synthesis of inositol-containing lipids, cell surface expansion terminated after one doubling of whole cells. In spheroplasts, cessation of membrane expansion was apparently followed by rapid development of an osmotic imbalance, causing lysis. Continued synthesis and accumulation of cytoplasmic constituents within the limited cell volume were implicated as a cause of the osmotic imbalance. In whole cells, an increase in internal osmotic pressure also follows termination of membrane and cell wall expansion. The cell wall prevents lysis, allowing a state of increasing cytoplasmic osmotic pressure to persist in the period preceding onset of inositol-less death.
Biochemical-genetic study of the first enzyme of histidine biosynthesis in Salmonella typhimurium: substrate and feedback binding regions
Authors: Wainscott V J , Ferretti J J
Published: January 2020

Twenty-five strains of Salmonella typhimurium containing different mutations in the first gene of histidine biosynthesis were studied to correlate regions of the genetic map with biochemical functions. These strains contained either missense, double-frameshift, or suppressed nonsense mutations, all of which resulted in altered, though active, enzymes. Each mutant enzyme was assayed for activity in the presence of varying concentrations of the feedback inhibitor L-histidine or the substrates ATP and 5-phosphoribosyl-1-pyrophosphate. The feedback properties and substrate kinetics of each mutant enzyme were compared to wild-type values, and these results indicated that the following functions were correlated with regions of the hisG gene: feedback inhibition in two general areas, including regions IA and IB and regions V, VI, and VII; ATP binding in two general areas, including regions IA, IB, and II and regions V, VI, and VII; and 5-phosphoribosyl-1-pyrophosphate binding in two general areas, including regions IB, II, and III and regions V and VI.
Peptide utilization in Pseudomonas aeruginosa: evidence for membrane-associated peptidase
Authors: Miller R V , Becker J M
Published: January 2020

A methionine auxotroph of Pseudomonas aeruginosa grew on methionine-containing peptides as a source of the required amino acid. Amino-terminus-blocked peptides would not serve as growth substrates, despite the fact that peptidases active on these blocked peptides were readily detectable in cell extracts. No evidence was found for extracellular enzymes capable of degrading the oligopeptides investigated. The degradative enzymes were not found in the periplasmic space of the cellular envelope. A high proportion of cellular peptidase activity was associated with the particulate (membrane) fraction of the cell lysate.
Mapping of the mecillinam-resistant, round morphological mutants of Escherichia coli
Authors: Iwaya M , Jones C W , Khorana J , Strominger J L
Published: January 2020

Genes responsible for round morphology in mecillinam-resistant, round morphological mutants of Escherichia coli have been mapped. Three mutants, called rodX, mapped at around 14 min, and two, called rodY, mapped at around 70 min by P1 transduction. These are either the same or very close to the loci reported, respectively, for the rodA (H. Matsuzawa, K. Hayakawa, T. Sato, and K. Imahori, J. Bacteriol. 115:436-442, 1973) and envB genes (B. Westling-Häggström and S. Normark, J. Bacteriol. 123:75-82, 1975). This suggests that mecillinam can be used very efficiently to select for found morphological mutants of rodA and envB after nitrosoguanidine treatment.
Changes in cytochrome content and electron transport patterns in Pseudomonas putida as a function of growth phase
Authors: Sweet W J , Peterson J A
Published: January 2020

Optical absorbance difference spectra of membrane vesicles prepared from aerobically grown Pseudomonas putida indicated that, when harvested in logarithmic phase, the cells contained one c-type cytochrome and two or three b-type cytochromes, one of which was cytochrome o. As the cells grew into stationary phase and the oxygen concentration of the medium dropped to essentially zero, an additional component believed to be cytochrome d was produced. Both the o- and d-type cytochromes might function as terminal oxidases. No a-type cytochromes could be detected at any stage of growth. Polarographic measurement of oxygen utilization revealed that cyanide and azide are effective inhibitors of the oxidation of ascorbate coupled with 2,6-dichlorophenolindophenol or N,N,N',N'-tetramethyl-p-phenylenediamine in respiratory particles from either log-phase or stationary-phase cells. Reduced nicotinamide adenine dinucleotide- or succinate-dependent oxygen utilization, however, was sensitive to these inhibitors only in log-phase particles. These results indicate that an alternate terminal oxidase may be synthesized by this organism in response to restricted oxygen availability and that branching of the respiratory system may result.
Effect of thymine concentration on cell shape in Thy- Escherichia coli B/r
Authors: Meacock P A , Pritchard R H , Roberts E M
Published: January 2020

Cells of a thymineless mutant of Escherichia coli B/r are shown to change their shape when the concentration of thymine in the growth medium is reduced. Electron micrographs of whole cells and isolated sacculi were used to make quantitative measurements of the changes in cell length and width which occur as a result of such a change in thymine concentration. The results showed that there is an increase in cell volume, which is due to an increase in cell width accompanied by a decrease in cell length. These changes were compared with the predictions of models which assume that cell shape is influenced by the chromosome replication cycle.
Conjugal transfer system of plasmid RP4: analysis by transposon 7 insertion
Authors: Barth P T , Grinter N J , Bradley D E
Published: January 2020

We have begun an analysis in Escherichia coli of the conjugal transfer functions of the broad-host-range plasmid RP4. We have isolated 19 tra mutants of RP4, generated by insertion of transposon 7, and mapped their insertion sites by restriction endonuclease analysis. These sites fall into two separate regions on either side of the kanamycin resistance determinant. The transfer rates of the mutants range from 10% of that of RP4 to an undetectable level. Spot tests with the P-1 pilus-specific phages PRR1, Pf3, and PR4 and electron microscopic examination for pili have classified the mutants into several phenotypes consistent with their having normal, retracted, or no pili. Analysis of transient plasmid heterozygotes, created by P1 transduction, divided the tra mutants into a minimum of five complementation groups. Some of these groups contain more than one phenotypic class and may represent more than one gene because of the possible polar and deletion effects of Tn7 insertion.
Single-strand breakage in DNA of Escherichia coli exposed to Cd2+
Authors: Mitra R S , Bernstein I A
Published: January 2020

When a growing culture of Escherichia coli was exposed to 3 X 10(-6) M Cd2+, 85 to 95% of the cells lost their ability to form colonies on agar plates. Loss of viability was accompanied by considerable single-strand breakage in the DNA, with no detectable increase in double-strand breaks. A direct correlation appeared to exist between the number of single-strand breaks and the concentrations of Cd2+ to which the cells were exposed. Exposure of DNA in vitro to a Cd2+ concentration of 3 X 10(-6) M or higher, followed by sedimentation in alkaline sucrose gradients, demonstrated no single-strand breaks. Cadmium-exposed cells recovered viability when incubated in Cd2+-free liquid medium containing 10 mM hydroxyurea. During the early period of recovery, there was a lag in the incorporation of labeled thymidine, but cellular DNA, at least in part, appeared to be repaired.
Identification of the Escherichia coli cell division gene sep and organization of the cell division-cell envelope genes in the sep-mur-ftsA-envA cluster as determined with specialized transducing lambda bacteriophages
Authors: Fletcher G , Irwin C A , Henson J M , Fillingim C , Malone M M , Walker J R
Published: January 2020

From a lysogen with lambda integrated in the leu operon, specialized transducing phages that carry the cell division, murein biosynthesis, and envelope permeability genes located about 0.5 min to the right of leu were isolated. These phages were used to identify the previously undiscovered cell division gene sep. A genetic map proves that sep is located in the sequence leuA sep murE murF murC ddl ftsA envA. A physical map of this region was prepared by heteroduplex analysis of the phage DNAs. Overlapping segments of host DNA extended rightward for as much as 26.4 kilobase pairs from the prophage insertion point (thought to be in leuA) to include all the genes through envA.
Cyclic AMP regulation of the hexose phosphate transport system in Escherichia coli
Authors: Ezzell J W , Dobrogosz W J
Published: January 2020

Synthesis of the hexosephosphate transport system in Escherichia coli required the cyclic AMP-receptor protein regulatory complex. The apparent Km value for hexosephosphate activity was affected by the level of phosphate in the uptake environment.
Polyadenylic acid sequences in the RNA of Hyphomicrobium
Authors: Schultz G A , Chaconas G , Moore R L
Published: January 2020

Heterogeneous RNA containing polyadenylic acid [poly(A)] sequence has been isolated from Hyphomicrobium by affinity chromatography on oligothymidylic acid cellulose and polyuridylic acid Sepharose columns. About 0.1 to 0.3% of [3H]adenine-labeled RNA over a 60-min period is associated with poly(A) sequences. This percentage decreases to about 0.03 in a 20-h labeling period. The poly(A) tracts recovered after digestion with ribonuclease A and T1 are composed of greater than 95% adenine residues and are up to 200 nucleotides in length with a predominant range of 15 to 40 nucleotides. Adenosine and AMP are present in the ratio of 1:36 in alkaline digests of Hyphomicrobium poly(A) tracts. This is compatible with nucleotide lengths determined on acrylamide gels and location at the 3'-OH terminus of the RNA molecule.
sn-Glycerol-3-phosphate dehydrogenase and its interaction with nitrate reductase in wild-type and hem mutant strains of Staphylococcus aureus
Authors: Lascelles J
Published: January 2020

Staphylococcus aureus has membrane-associated sn-glycerol-3-phosphate dehydrogenase activity that is strongly activated by detergents. The enzyme can be measured spectrophotometrically in intact cells in assay systems containing lauryldimethylamine oxide (Ammonyx LO). The dehydrogenase activity was located exclusively in the membrane fraction of cells grown with glycerol under aerobic conditions or under anaerobic conditions with the addition of nitrate; there was no evidence of multiple forms. Development of sn-glycerol-3-phosphate dehydrogenase activity was studied with suspensions of cells grown previously under semianaerobic conditions with glucose and nitrate. The wild-type strain rapidly formed the enzyme when incubated with glycerol under aerobic conditions or under semianaerobic conditions in the presence of nitrate. Under similar conditions, suspensions of hem mutant H-14 required the addition of hemin. Induction of the enzyme was strongly repressed by glucose with both organisms. A procedure was established to obtain cells of mutant H-14 with sn-glycerol-3-phosphate dehydrogenase and nitrate reductase activities, but which could not link the systems unless supplemented with hemin. The coupled activity could also be reconstructed in vitro by the addition of hemin to the depleted membranes.
Microbial Oxidation of Methane and Methanol: Crystallization of Methanol Dehydrogenase and Properties of Holo- and Apo-Methanol Dehydrogenase from
Methylomonas methanica
Authors: Patel Ramesh N. , Hou Ching T. , Felix Andre
Published: January 2020

Procedures are described for the purification and crystallization of methanol dehydrogenase from the soluble fraction of the type I obligate methylotroph
Methylomonas methanica
strain S1. The crystallized enzyme is homogeneous as judged by acrylamide gel electrophoresis and ultracentrifugation. The enzyme had a high pH optimum (9.5) and required ammonium salt as an activator. In the presence of phenazine methosulfate as an electron acceptor, the enzyme catalyzed the oxidation of primary alcohols and formaldehyde. Secondary, tertiary, and aromatic alcohols were not oxidized. The molecular weight as well as subunit size of methanol dehydrogenase was 60,000, indicating that it is monomeric. The sedimentation constant (
s
20,w
) was 3.1S. The amino acid composition of the crystallized enzyme is also presented. Antisera prepared against the crystalline enzyme were nonspecific; they cross-reacted with and inhibited the isofunctional enzyme from other obligate methylotrophic bacteria. The crystalline methanol dehydrogenase had an absorption peak at 350 nm in the visible region and weak fluorescence peaks at 440 and 470 nm due to the presence of a pteridine derivative as the prosthetic group. A procedure was developed for the preparation of apo-methanol dehydrogenase. The molecular weights, sedimentation constants, electrophoretic mobilities, and immunological properties of apo- and holo-methanol dehydrogenases are identical. Apo-methanol dehydrogenase lacked the absorption peak at 350 nm and the fluorescence peaks at 440 and 470 nm and was catalytically inactive. All attempts to reconstitute an active enzyme from apo-methanol dehydrogenase, using various pteridine derivatives, were unsuccessful.
Mapping of a genetic locus that affects glycerol 3-phosphate transport in Bacillus subtilis
Authors: Lindgren V
Published: January 2020

Two types of fosfomycin-resistant mutants of Bacillus subtilis were isolated. Mutants of the first type (GlpT mutants) were resistant to at least 200 microgram of fosfomycin per ml and failed to take up exogenous glycerol 3-phosphate. Mutants of the second type were resistant to lower concentrations of fosfomycin and transported glycerol-3-phosphate as efficiently as wild-type bacteria. The glpT mutations, but not the mutations in the second type of fosfomycin-resistant mutants, map in the cysA-aroI region of the B. subtilis chromosome.
dnaA acts before dnaC in the initiation of DNA replication
Authors: Kung F C , Glaser D A
Published: January 2020

We constructed a double mutant of Escherichia coli K-12 carrying dnaA(Ts) and dnaC(Cs) lesions. In this mutant DNA synthesis proeceeds normally at 32 degrees C and initiation is inhibited at both 41 and 20 degrees C. By shifting this culture grown at 32 degrees C to the two restrictive temperatures in different time sequences and assaying protein and DNA synthesis of cells growing at different temperatures, we found that dnaA and dnaC genes work independently with dnaA acting before dnaC. While preparing special strains for this work, we also showed that the order of genes in the neighborhood of dnaA is dnaA-tnaA-phoS-ilv.