bluuebunny/crossref_metadata_2025 huggingface dataset:
Fractionation of membrane vesicles from coliphage M13-infected Escherichia coli
Authors: Wickner W
Published: January 2020

Membrane vesicles were prepared by osmotic lysis of spheroplasts from M13-infected Escherichia coli. Reduced nicotinamide adenine dinucleotide (NADH) oxidase (reduced NAD: oxidoreductase, EC 1.6.99.3) and Mg2+-Ca2+-activated adenosine triphosphatase (ATP phosphohydrolase, EC 3.6.1.3), which are normally localized to the inner surface of the cytoplasmic membrane, were 50% acceesible to their polar substrates in these vesicles. The major coat protein of coliphage M13 is also bound to the cytoplasmic membrane (prior to phage assembly) but with its antigenic sites exposed to the exterior of the cell. Antibody to M13 coat protein was used to fractionate membrane vesicles. Neither agglutinated nor unagglutinated vesicles had altered NADH oxidase and adenosine triphosphatase specific activities. This is inconsistent with such vesicles being a mixture of correctly oriented and completely inverted membrane sacs and suggests that NADH oxidase, adenosine triphosphatase, M13 coat protein, or all three proteins rearrange during vesicle preparation.
Kinetic properties of Serratia marcescens adenosine 5'-diphosphate glucose pyrophosphorylase
Authors: Preiss J , Crawford K , Downey J , Lammel C , Greenberg E
Published: January 2020

The regulatory properties of partially purified adenosine 5'-diphosphate-(ADP) glucose pyrophosphorylase from two Serratia marcescens strains (ATCC 274 and ATCC 15365) have been studied. Slight or negligible activation by fructose-P2, pyridoxal-phosphate, or reduced nicotinamide adenine dinucleotide phosphate (NADPH) was observed. These compounds were previously shown to be potent activators of the ADPglucose pyrophosphorylases from the enterics, Salmonella typhimurium, Enterobacter aerogenes, Enterobacter cloacae, Citrobacter freundii, Escherichia aurescens, Shigella dysenteriae, and Escherichia coli. Phosphoenolpyruvate stimulated the rate of ADPglucose synthesis catalyzed by Serratia ADPglucose pyrophosphorylase about 1.5- to 2-fold but did not affect the S0.5 values (concentration of substrate required for 50% maximal stimulation) of the substrates, alpha-glucose-1-phosphate, and adenosine 5'-triphosphate. Adenosine 5'-monophosphate (AMP), a potent inhibitor of the enteric ADPglucose pyrophosphorylase, is an effective inhibitor of the S. marcescens enzyme. ADP also inhibits but is not as effective as AMP. Activators of the enteric enzyme counteract the inhibition caused by AMP. This is in contrast to what is observed for the S. marcescens enzyme. Neither phosphoenolpyruvate, fructose-diphosphate, pyridoxal-phosphate, NADPH, 3-phosphoglycerate, fructose-6-phosphate, nor pyruvate effect the inhibition caused by AMP. The properties of the S. marcescens HY strain and Serratia liquefaciens ADPglucose pyrophosphorylase were found to be similar to the above two S. marcescens enzymes with respect to activation and inhibition. These observations provide another example where the properties of an enzyme found in the genus Serratia have been found to be different from the properties of the same enzyme present in the enteric genera Escherichia, Salmonella, Shigella, Citrobacter, and Enterobacter.
Characterization of group B colicin-resistant mutants of Escherichia coli K-12: colicin resistance and the role of enterochelin
Authors: Pugsley A P , Reeves P
Published: January 2020

Nine classes of group B colicin-resistant mutants were examined to study the role of enterochelin in colicin resistance. Four of the mutants studied (cbt, exbC, exbB, and tonB) hypersecreted enterochelin. Enterochelin hypersecretion was apparently responsible for resistance of the exbC mutant to colicins G and H and for resistance of the exbB mutant to colicins G, H, Ia, Ib, S1, and V. All four mutants scored as colicin B tolerant, even in the absence of enterochelin synthesis. The mutants produced substantially increased amounts of two high-molecular-weight outer membrane polypeptides when grown under limiting iron conditions. The presence of these polypeptides was correlated with increased colicin B-neutralizing activity in the outer membrane preparations.
Similarity in properties and mapping of three Rec mutants of Haemophilus influenzae
Authors: Kooistra J , Setlow J K
Published: January 2020

Three Rec- mutants of Haemophilus influenzae have been studied with respect to their transformability, ultraviolet and mitomycin C sensitivities, spontaneous and ultraviolet-induced deoxyribonucleic acid breakdown, inducibility of lysogens, and the linkage of the three mutations to a streptomycin resistance marker. The data indicate that the three mutations cause the same phenotypic changes, and that they are all on the same gene. Transformability of the mutants is different when two different media are used for competence development, although transformability with the two competence methods is not different in a Rec- strain that is mutant at another gene.
Ultrastructural visualization of anionic sites on mycoplasma membranes by polycationic ferritin
Authors: Schiefer H G , Krauss H , Brunner H , Gerhardt U
Published: January 2020

Anionic sites on mycoplasma membranes were visualized in the electron microscope by a polycationized ferritin derivative. The technique of thin sectioning was used. Staining prior to fixation led to clustering of ferritin granules on the mycoplasma cell surface. On glutaraldehyde-fixed Mycoplasma mycoides subsp. capri, M. gallisepticum, M. pneumoniae, and Acholeplasma laidlawii, the anionic sites were uniformly distributed over the entire membrane surface. M. hominis did not bind the polycationic ferritin label. Chemical and enzymatic treatments of the mycoplasmas indicated that the anionic sites may be lipid phosphate groups. Isolated M. mycoides subsp. capri membranes were labeled exclusively on only one membrane surface, presumably the outer one. Liposomes prepared from diphosphatidylglycerol and phosphatidylcholine were also labeled by the polycationic ferritin.
D-Ribulose-1,5-bisphosphate carboxylase and polyhedral inclusion bodies in Thiobacillus intermedius
Authors: Purohit K , McFadden B A , Shaykh M M
Published: January 2020

The growth-related parameters of Thiobacillus intermedius, cultured in glutamate-CO2-S2O32- medium, have been determined. After centrifugation at 48,000 X g for 1 h, 24% of the D-ribulose-1,5-bisphosphate carboxylase (RuBPCase) activity of the disrupted-cell suspensions obtained from CO2-S2O32--and glutamate-CO2-S2O3(3)- grown cells could be sedimented, and the specific activities of this enzyme in the supernatant fractions were almost equivalent. The enzyme was stable in T. intermedius starved of thiosulfate in the presence and absence of glutamate, but a progressive decrease was evident in several growth cycles, each cycle supported by resupplementation of cells with thiosulfate. Polyhedral inclusion bodies were present in CO2-S2O3(2)- and glutamate-CO2S2O3(2)- grown cells. The number of polyhedral bodies per cell increased during mixotrophic growth approximately in proportion to the observed increase in the specific activity of RuBPCase. RuBPCase could not be detected in T. intermedius grown heterotrophically on yeast extract, nor could polyhedral bodies be found.
Association of messenger ribonucleic acid with 70S monosomes from down-shifted Escherichia coli
Authors: Jacobson L A , Baldassare J C
Published: January 2020

The complexed 70S ribosomes (monosomes) that accumulate in Escherichia coli after an energy source shift-down were examined in an electron microscope. In all cases, the ribosomes lie at or near one end of a ribonucleic acid (RNA) strand. This messenger RNA (mRNA) has a mean length of 168 nm and a length-average length of 200 nm, sufficient to code for polypeptides of a weight-average molecular weight of 20,000. The length distribution indicates that these strands are a reasonable representation of the population of monocistronic mRNA's of E. coli. The mRNA strands disappear entirely upon digestion with pancreatic ribonuclease, phosphodiesterase I, or polynucleotide phosphorylase. The susceptibility to digestion by 3'-exonucleases indicate that the ribosomes lie at the 5' end of the mRNA strands. These results are consistent with the hypothesis that down-shifted cells have a translational defect at a point subsequent to the binding of ribosomes to mRNA but prior to the formation of the first peptide bond, such that ribosomes remain bound at or near their points of initial attachment to mRNA.
Identification of the Major Penicillin-Binding Proteins of
Escherichia coli
as
d
-Alanine Carboxypeptidase IA
Authors: Spratt Brian G. , Strominger Jack L.
Published: January 2020

Penicillin-binding proteins 5 and 6 of
Escherichia coli
have been identified as
d
-alanine carboxypeptidase IA.
Expression and regulation of lactose genes carried by plasmids
Authors: Guiso N , Ullmann A
Published: January 2020

A number of plasmids carrying the lactose character have been studied. All of the plasmids examined so far code for proteins essential for lactose utilization, i.e., beta-galactosidase and galactoside permease. None of them carries enzymatically or immunologically detectable thiogalactoside transacetylase. The expression of the two enzymes is both negatively and positively controlled: they are inducible by different galactosides and are sensitive to catabolite repression. Since the plasmid-coded lactose systems have many features in common with the Escherichia coli lactose operon, it is suggested that the plasmids could have acquired the lactose genes from an E. coli chromosome.
Soluble adenylate cyclase from the culture medium of Bordetella pertussis: purification and characterization
Authors: Hewlett E , Wolff J
Published: January 2020

Culture medium of exponentially growing Bordetella pertussis (strain 114) contains significant quantities of soluble (100,000 X g for 1 h) adenylate cyclase. The enzyme was purified by chromatography on diethylaminoethyl-cellulose and Sephadex G-200. The purest material yielded a single band on sodium dodecyl sulfate-disc gel electrophoresis. It is heat labile, has a temperature optimum of 30 degrees C, a pH optimum of pH 7 to 8, and a Km for adenosine 5'-triphosphate of 0.4 mM, and requires Mg2+ for maximum activity. The molecular weight, by sodium dodecyl sulfate-disc gel electrophoresis and sucrose density gradient, is approximately 70,000. The enzyme is markedly inhibited by fluoride and weakly inhibited by monovalent salts, but its activity is not altered by alpha-keto acids of nonsubstrate nucleoside triphosphates. Thus, but its presence in the culture supernatant, its smaller molecular weight, and its insensitivity to alpha-keto acids and nucleotides, this enzyme differs from the bacterial adenylate cyclases previously described.
Involvement of 4-hydroxymandelic acid in the degradation of mandelic acid by Pseudomonas convexa
Authors: Bhat S G , Vaidyanathan C S
Published: January 2020

A microorganism capable of degrading DL-mandelic acid was isolated from sewage sediment of enrichment culture and was identified as Pseudomonas convexa. It was found to metabolize mandelic acid by a new pathway involving 4-hydroxymandelic acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, and 3,4-dihydroxybenzoic acid as aromatic intermediates. All the enzymes of the pathway were demonstrated in cell-free extracts. L-Mandelate-4-hydroxylase, a soluble enzyme, requires tetrahydropteridine, nicotinamide adenine dinucleotide phosphate, reduced form, and Fe2+ for its activity. The next enzyme, L-4-hydroxymandelate oxidase (decarboxylating), a particulate enzyme, requires flavine adenine dinucleotide and Mn2+ for its activity. A nicotinamide adenine dinucleotide-dependent, as well as a nicotinamide adenine dinucleotide phosphate-dependent, benzaldehyde dehydrogenase has been resolved and partially purified.
Genetic linkage of chromosomal tetracycline resistance and pigmentation to a purine auxotrophic marker and the isoleucine-valine-leucine structural genes in Staphylococcus aureus
Authors: Pattee P A
Published: January 2020

Three tetracycline resistance determinants (tmn-3106, tmn-3110, and tmn-3511) reported by Asheshov (1975) to be chromosomal in Staphylococcus aureus have been linked by transformation to a purine auxotrophic marker (pur-110), a cluster of eight genes involved in the biosynthesis of isoleucine, valine, and leucine (the ilv-leu region), a marker (ilvR10) that may be involved in the regulation of the ilv-leu region, and a gene involved in pigmentation (pig-131). The linkage group thus defined is tmn-3106-pur-110-ilvR10-(ilv-leu)-pig-131. The orientation of the ilv-leu region relative to ilvR10 and pig-131 was not determined. The tmn-3106, tmn-3110, and tmn-3511 determinants exhibit the same linkage relationships to the other markers. It is concluded that this linkage group represents a portion of the chromosome of S. aureus.
Second-site mutations in capR (lon) strains of Escherichia coli K-12 that prevent radiation sensitivity and allow bacteriophage lambda to lysogenize
Authors: Gayda R C , Yamamoto L T , Markovitz A
Published: January 2020

capR (lon) mutants of Escherichia coli K-12 are mucoid and sensitive to ultraviolet (UV) and X-ray radiation as well as to nitrofurantoin. The mutants form filaments after exposure to these agents. capR mutants are also conditionally lethal since they die when plated on complex medium even without UV treatment; this phenomenon is designated "complex medium-induced killing". Furthermore, capR mutants are poorly lysogenized by bacteriophage lambda. Second-site revertants were isolated by plating on media containing nitrofurantoin. All 17 of the independent revertants studied were still mucoid but resistant to UV radiation. Sixteen of the 17 revertants contained a mutation, sulA, that cotransduced with pyrD (21 min). A second locus, sulB, was also found that cotransduced with leu (2 min). Studies with partial diploids (F'pyrD+ sulA+/pyrD36 sulA17 capR9 (lon) demonstrated that sulA+ is dominant to sulA; thus the indicated partial diploid is UV sensitive, whereas the haploid parent is UV resistant. Furthermore, two other phenotypic traits of capR (lon) mutants were reversed by the sul mutation:complex medium-induced killing and the inability of lambda phage to efficiently lysogenize capR strains. On the basis of these and other results, the following model is suggested to explain capR (lon) and sul gene interactions. capR (lon) is a regulator gene for the structural genes sulA+ and sulB+. Depression of both sul operons results in UV sensitivity and decreased ability of lambda to lysogenize, whereas inactivation of either sul+ protein by mutation to sul prevents these phenomena.
Depression of uracil uptake by ammonium in Neurospora crassa
Authors: Magill J M , Edwards E S , Sabina R L , Magill C W
Published: January 2020

The mechanism of uracil uptake and one aspect of its regulation were studied in germinated conidia of Neurospora crassa. Uracil was found to be taken up by a transport mechanism that did not exhibit Michaelis-Menten kinetics. Rather, the kinetic patterns indicated two separate systems or a single transport mechanism with negative cooperativity. Cytosine and thymine inhibited uracil uptake, but uridine did not. The mutant strain uc-5-pyr-1, which failed to transport uracil, was used in reversion studies and to map the uc-5 locus. Spontaneous reversion rates at the uc-5 locus were found to be approximately 2 x 10(-8), indicating that the uc-5 lesion results from a single mutation. Loss of the uracil transport function through a single mutation favors the model of a single transport mechanism with negative cooperativity. Uracil uptake was significantly decreased in the presence of NH 4+, and evidence is presented for repression by NH4+ of a uracil transport system. Growth rates of pyrimidine-requiring and wild-type strains measured in the presence and absence of NH4+, with uracil as the pyrimidine supplement, showed that NH4+ decreased the growth rates of the pyrimidine-requiring strains significantly, while having no effect on wild-type growth rates.
Effects of phenethyl alcohol on Bacillus and Streptococcus
Authors: Silva M T , Sousa J C , Macedo M A , Polónia J , Parente A M
Published: January 2020

The activity of phenethyl alcohol (PEA) on Bacillus cereus, B. megaterium, and Streptococcus faecalis was studied by electron microscopy of thin sections and by the assay of intracellular K+ leakage. S. faecalis was unaffected by PEA at concentrations up to 0.5%, B. cereus was severely damaged by 0.5% PEA, and B. megaterium behaved intermediately. Important membrane ultrastructural alterations were observed in B. cereus cells treated with 0.5% PEA, namely the change in the geometry of the membrane profile from asymmetric to symmetric, the occurrence of prominent, complex mesosome-like structures, and membrane fracturing and solubilization. Protoplasts from B. megaterium were found to be quickly lysed by 0.5% PEA due to the disruption of the cytoplasmic membrane. The electron microscopic observations, together with the results of the study of the K+ efflux from B. cereus and B. megaterium, indicate that PEA primarily and directly damages the cytoplasmic membrane of sensitive bacteria. The breakdown of the permeability barrier probably is responsible for the observed bactericidal action of 0.5% PEA on B. cereus.
Septation deficiency and phosphilipid perturbation in Escherichia coli genetically constitutive for the beta oxidation pathway
Authors: Vanderwinkel E , De Vlieghere M , Fontaine M , Charles D , Denamur F , Vandevoorde D , De Kegel D
Published: January 2020

Mutants of Escherichia coli defective in the regulation of the fatty acids beta oxidation pathway show an ultrastructural deficiency in septum formation at high growth rate. Several independent pairs of parent and mutant strains have been analyzed biochemically. Each parent strain displays a well-defined pattern of cellular phospholipids, which varies with the growth conditions. High ratios of phosphatidylglycerol to cardiolipin characterize fast-growth conditions. None of the mutant strains, although they grow in mass nearly as rapidly as their respective parents, can reach these high ratios. The beta oxidation pathway regulatory mutation leads to an increased turnover of the glycerol moieties of these phospholipids in the inner as well as in the outer cell membrane.
Effect of polymyxin on the ultrastructure of the outer membrane of wild-type and polymyxin-resistant strain of Salmonella
Authors: Lounatmaa K , Mäkelä P H , Sarvas M
Published: January 2020

The effect of polymyxin on two sets of Salmonella mutants was studied by thin-section and scanning electron microscopy. Polymyxin (in increasing concentrations, starting just below bactericidal effect) caused the appearance of the previously described rodlike projections on the cell surface of wild-type (smooth, polymyxin-sensitive) bacteria. These projections seemed to involve the outer membrane of the cell wall. In rough mutants, which are deficient in lipopolysaccharide, the projections were much smaller and flat. Higher concentrations of polymyxin were required to produce morphological effects in polyxmin-resistant mutants of both smooth and rough forms. Furthermore, in these mutants polymyxin caused vesicle-like bulging of the total outer membrane quite different in appearance from the rodlike projections of the wild type.
Electron Microscope Study of Sporulation and Parasporal Crystal Formation in
Bacillus thuringiensis
Authors: Bechtel Donald B. , Bulla Lee A.
Published: January 2020

A comprehensive ultrastructural analysis of sporulation and parasporal crystal development is described for
Bacillus thuringiensis
. The insecticidal crystal of
B. thuringiensis
is initiated at the start of engulfment and is nearly complete by the time the exosporium forms. The crystal and a heretofore unobserved ovoid inclusion develop without any clear association with the forespore septum, exosporium, or mesosomes. These observations contradict previous hypotheses that the crystal is synthesized on the forespore membrane, exosporium, or mesosomes. Formation of forespore septa involves densely staining, double-membrane-bound, vesicular mesosomes that have a bridged appearance. Forespore engulfment is subpolar and also involves mesosomes. Upon completion of engulfment the following cytoplasmic changes occur: decrease in electron density of the incipient forespore membrane; loss of bridged appearance of incipient forespore membrane; change in stainability of incipient forespore, forespore, and mother cell cytoplasms; and alteration in staining quality of plasma membrane. These changes are involved in the conversion of the incipient forespore into a forespore and reflect “commitment” to sporulation.
Isolation and characterization of the rodlet layer of Trichophyton mentagrophytes microconidial wall
Authors: Hashimoto T , Wu-Yuan C D , Blumenthal H J
Published: January 2020

The rodlet layer of the microconidial wall of Trichophyton mentagrophytes was isolated and partially characterized. The purified microconidial walls were first extracted with urea (8M), mercaptoethanol (1%), and sodium dodecyl sulfate (1%) followed by enzymatic digestion with glusulase (snail intestinal enzymes) and purified (1 leads to 3)-beta-D-glucanase and chitinase. The purified rodlet layer was 15 to 30 nm thick and accounted for approximately 10% of the original wall weight. The pattern of rodlet patches, as revealed by electron microscopy of freeze-etched preparations of the isolated layer, was essentially the same as that observed on the intact microconidial wall. The rodlet layer was found to be resistant to most of the common organic solvents, cell wall lytic enzymes, mild acid treatments, and surface-active agents, but was solubilized in boiling 1 N NaOH with concomitant disorientation of the rodlet patterns. A melanin or melanin-like pigment appeared to be intimately associated with this rodlet layer and was solubilized during a hot-alkali treatment. Protein (80 to 85%) and glucomannan (7 to 10%) were the major components of the rodlet layer. The rodlet layer did not contain any appreciable amounts of lipid or phosphorus.
Mutant of
Pseudomonas aeruginosa
18S That Synthesizes Type Id β-Lactamase Constitutively
Authors: Flett F. , Curtis N. A. C. , Richmond M. H.
Published: January 2020

A mutant of
Pseudomonas aeruginosa
18S that constitutively synthesizes type Id β-lactamase was isolated and some of its properties were elucidated.
Interaction of Pseudomonas and Enterobacteriaceae plasmids in Aeromonas salmonicida
Authors: Olsen R H , Wright C D
Published: January 2020

We observed that Aeromonas salmonicida ARO200 will maintain either or both the Pseudomonas R-factor, pMG1, and Enterobacteriaceae R-factors. This bacterial strain, therefore, provides a unique background wherein the host ranges of Pseudomonas and Enterobacteriaceae plasmods overlap. Co-maintenance of these plasmids resulted in behavior of plasmid aggregates that allowed transfer of R-dterminants beyond the host range of the parent plasmid. We observed that the ARO200 genetic background facilitated the redistribution of B determinants among unrelated and conjugally noninterfertile gram-negative bacteria. Aberrant behavior resulting in the deletion of R-determinants for plasmids singly maintained in ARO200 was also observed. Plasmids studied included RP1, R702, IncP; Rs-a, IncW; R192.7, IncFII; R64-11, IncI; R390, IncN; and R6K, IncX.
Regulation of purine utilization in bacteria. VII. Involvement of membrane-associated nucleoside phosphorylase in the uptake and the base-mediated loss of the ribose moiety of nucleosides by Salmonella typhimurium membrane vesicles
Authors: Rader R L , Hochstadt J
Published: January 2020

Although uridine and adenosine are converted by membrane-associated nucleoside phosphorylases to ribose-1-phosphate (ribose-1-P) and the corresponding bases (uracil and adenine), only ribose -1-P is accumulated within Salmonella typhimurium LT2 membrane vesicles. In accordance with these observations, no uptake is observed when the vesicles are incubated with the bases or nucleosides labeled in their base moieties. The vesicles lack a transport system for ribos-1-P, since excess ribose-1-P does not inhibit the uptake of the ribose moiety of uridine. In addition, there is no exchange with preaccumulatedribose-1-P. Thus, uridine, rather than ribose-1-P, must serve as the initially transported substrate. The uptake of the ribose portion of uridine is coupled to electron transport, and the levels to which ribose-1-P are accumulated may be reduced by adding various bases to the reaction mixtures. The bases appear to inhibit the uridine phosphorylase reaction and/or cause an efflux of ribose-1-P from the vesicles. This loss of ribose-1-P reflects the accumulation of nucleosides in the external medium after being synthesized within the membranes. Synthesis of the nucleosides from intravesicular ribose-1-P and exogenous base proceeds even though the bases are not accumulated by the vesicles. Furthermore, ribose-1-P cannot significantly inhibit uridine phosphorylase activity unless the membranes are disrupted. These observations indicate that the membrane-associated nucleoside phosphorylases may have a transmembranal orientation with their base and ribose-1-P binding sites on opposite sides of the membranes. Such an asymmetric arrangement of these enzymes may facilitate the uptake of the ribosyl moiety of nucleosides by a group translocation mechanism. Thus, nucleosides may be cleaved during the membrane transport process, with the resultant bases delivered to the external environment while ribose-1-P is shunted to the intravesicular space.
Growth response of Escherichia coli to nutritional shift-up: immediate division stimulation in slow-growing cells
Authors: Sloan J B , Urban J E
Published: January 2020

When Escherichia coli 15T- cells growing exponentially at 70- to 80-min doubling times are subjected to a nutritional shift-up via glucose addition, cell division continues at the preshift rate for about 70 min (rate maintenance). The same cells growing at doubling times of 120 min or longer, however, begin to divide at a new faster rate immediately upon glucose addition. In both the rate maintenance and immediate division situations, cell mass, as measured by optical density (OD), begins to increase immediately upon shift-up. Consequently, the OD/cell pattern differs in the two growth-rate transitions. During rate maintenance, the OD/cell ratio increases dramatically for 60 to 70 min, and then slows appreciably and approaches the OD/cell characteristic of the new medium. During immediate division situations, the OD/cell increases only slightly for the first 180 +/- min; then the rate of increase accelerates but does not stop at the OD/cell characteristic of the new medium. Immediate division upon nutritional shift-up apparently depends upon initial doubling times in excess of 115 to 120 min and provision of a readily metabolized carbon source supporting doubling times of about 40 min. Similar immediate division occurs in E. coli B/r and K-12.
Transformation of Streptococcus sanguis Challis by plasmid deoxyribonucleic acid from Streptococcus faecalis
Authors: LeBlanc D J , Hassell F P
Published: January 2020

Plasmid deoxyribonucleic acid (DNA) from Streptococcus faecalis, strain DS5, was transferred to the Challis strain of Streptococcus sanguis by transformation. Two antibiotic resistance markers carried by the beta plasmid from strain DS5, erythromycin and lincomycin, were transferred to S. sanguis at a maximum frequency of 1.8 x 10-5/colony-forming unit. Approximately 70% of the covalently closed circular DNA isolated from transformant cultures by dye buoyant density gradients was shown to be hybridizable to beta plasmid DNA. Two major differences were observed between the beta plasmid from S. faecalis and the plasmid isolated from transformed S. sanguis: (i) the beta plasmid from strain DS5 sedimented in velocity gradients at 43S, whereas the covalently closed circular DNA from transformed Challis sedimented at 41S, suggesting a 1.5-Mdal deletion from the beta plasmid occurred; (ii) although the 43S beta plasmid remained in the supercoiled configuration for several weeks after isolation, the 41S plasmid was rapidly converted to a linear double-stranded molecule. Attempts to transform S. sanguis with the alpha plasmid from S. faecalis, strain DS5, were unsuccessful.
Mutational alteration of a nitrogen-fixing bacterium to sensitivity to infection by bacteriophage Mu: isolation of nif mutations of Klebsiella pneumoniae M5al induced by Mu
Authors: Rao R N
Published: January 2020

The nitrogen-fixing bacterium Klebsiella pneumoniae M5al is not sensitive to infection by bacteriophage Mu. A mutant of K. pneumoniae that is sensitive to Mu infection was isolated. Several Mu-induced auxotrophic mutations of K. pneumoniae including nif, trp, and rtl were isolated and genetically characterized. Evidence is presented that the Mu-induced mutations of nif arise as the result of insertion of Mu within (or near) the nif operon(s). The rtl locus, which determines the ability to utilize ribitol as a carbon source, was found to be linked to nif loci.
Microbial oxidation of methane and methanol: crystallization and properties of methanol dehydrogenase from Methylosinus sporium
Authors: Patel R N , Felix A
Published: January 2020

Obligate methylotrophs are divisible into two types on the basis of ultrastructural biochemical characteristics. Both groups possess a soluble phenazine methosulfate (PMS)-dependent methanol dehydrogenase. In addition, particulate PMS-dependent methanol dehydrogenase and PMS-independent methanol oxidase have been found in the type I membrane group. A procedure was developed for the crystallization of methanol dehydrogenase from the soluble fraction of the type II obligate methylotroph Methylosinus sporium. This is the first report of a crystalline methanol dehydrogenase from a methylotrophic bacterium. The crystallized enzyme is homogeneous as judged by ultracentrifugation and by acrylamide gel electrophoresis. In the presence of an electron acceptor (phenazine or phenazinium compound) and an activator (ammonium compound), the crystallized enzyme catalyzed the oxidation of primary alcohols and formaldehyde. Secondary, tertiary, and aromatic alcohols were not oxidized. The molecular weight of the enzyme as estimated by gel filtration is approximately 60,000, and as estimated by sedimentation equilibrium analysis it is 62,000. The sedimentation constant (S20,W) is 2.9. The subunit size determined by sodium dodecyl sulfate-gel electrophoresis is approximately 60,000. The amino acid composition and spectral properties of the enzyme are also presented. Antisera prepared against the crystalline enzyme are nonspecific, they cross-reacted and inhibited isofunctional enzymes from other obligate methylotrophic bacteria.
Regulation of arginine biosynthesis in Saccharomyces cerevisiae: isolation of a cis-dominant, constitutive mutant for ornithine carbamoyltransferase synthesis
Authors: Messenguy F
Published: January 2020

A cis-dominant mutation linked to argF, the structural gene specifying ornithine carbamoyltransferase, and affecting the control of the synthesis of this enzyme has been obtained. The level of ornithine carbamoyltransferase in this mutation is depressed and less repressible by addition of L-arginine than it is in the wild-type strain. Of 38 tetrads analyzed, resulting from a cross of a strain harboring this mutation with a strain carrying an argF- mutation, none was a tetratype or a nonparental ditype. This operator mutation helps to define a negative mode of control of the synthesis of the arginine biosynthetic enzymes, as had been suggested earlier upon the isolation of argRI- (arg80), argRII- (arg81), and argRIII- (arg82) specific regulatory mutations.
Thermal adaptation in yeast: growth temperatures, membrane lipid, and cytochrome composition of psychrophilic, mesophilic, and thermophilic yeasts
Authors: Arthur H , Watson K
Published: January 2020

The temperature limits of growth of a number of yeast species were examined, and on this basis the organisms were classified into different thermal categories. The following species were examined: Leucosporidium frigidum and Leucosporidium nivalis, psychrophilic, temperature limits of growth, -2 to 20 degrees C; Canadian lipolytica mesophilic, temperature limits of growth, 5 to 35 degrees Candida parapsilosis and Saccharomyces telluris, thermotolerant, temperature limits of growth, 8 to 42 degrees C; Torulopsis bovina and Candida slooffi, thermophilic, temperature limits of growth, 25 to 45 degrees C and 28 to 45 degrees C, respectively. The membrane lipid and cytochrome composition of mitochrondrial fractions isolated from these yeasts were compared. There was a direct correlation between the growth temperature and the degree of membrane of lipid unsaturation; the lower the temperature, the greater the degree of lipid unsaturation. The membrane lipid composition of the thermophilic yeasts were distinguished by the high percentage (30 to 40%) of saturated fatty acid, as compared with the mesophilic and psychrophilic yeasts. The latter contained approximately 90% unsaturated fatty acid, 55% of which was linolenic acid, C alpha-18:3. Changes in phospholipid composition in relation to temperature were also noted. The respiratory-deficient thermophile, C. slooffi, was characterized by the absence of cardiolipin (sensitivity 0.1 mug of phosphorus) and cytochrome aa3. The absence of conventional mitochondrial structures in this thermophilic microorganism is tentatively suggested although low concentrations of cytochromes b, c, and c1 were detected by low-temperature spectroscopy. On the other hand, the respiratory-competent thermophile, T. bovina, was characterized by a high cardiolipin (25% of the total phospholipid) and cytochrome aa3 content (1 nmol/mg of mitochrondrial protein). Low-temperature spectra showed the presence of one b-type cytochrome in the thermophilic yeasts, two b-type cytochromes in the mesophilic yeasts, and three b-type cytochromes in the psychrophilic yeasts. It was concluded that a knowledge of the properties of the biological membrane is fundamental to an understanding of the ability of a microorganism to grow and reproduce in different temperature environments.
Linkages between deoxyribonucleic acid synthesis and cell division in Myxococcus xanthus
Authors: Kimchi A , Rosenberg E
Published: January 2020

Addition of chloramphenicol or 0.5 M glycerol to growing Myxococcus xanthus resulted in an immediate cessation of cell division and 40% net increase in deoxyribonucleic acid (DNA). Although the chloramphenicol-treated cells divided in the presence of nalidixic acid after chloramphenicol was removed, glycerol-induced myxospores required DNA synthesis for subsequent cell division. Myxospores prepared from chloramphenicol-treated cells lost this potential to divide in the presence of nalidixic acid. The "critical period" of DNA synthesis necessary for cell division after germination overlapped in time (3 to 5 h) with initiation of net DNA synthesis. The length of the critical period of DNA synthesis was estimated at 12 min, or 5% of the M. xanthus chromosome. The requirement for cell division during germination also involved ribonucleic acid and protein synthesis after DNA synthesis. The data suggest that replication at or near the origin of the chromosome triggers the formation of a protein product that is necessary but not sufficient for subsequent cell division; DNA termination is also required. During myxospore formation, the postulated protein is destroyed, thereby reestablishing and making apparent this linkage between early DNA synthesis and cell division.
Repression of alkaline phosphatase in Salmonella typhimurium carrying a phoA+ phoR- episome from Escherichia coli
Authors: Yagil E , Hermoni E
Published: January 2020

Salmonella typhimurium does not produce alkaline phosphatase (nor beta-galactosidase). Nevertheless, it has the function of the phoR+ regulatory gene but lacks the function of the lacI+ regulatory gene. Several periplasmic proteins are derepressed when cells of S. typhimurium are starved for inorganic phosphate. The role of phoR is discussed.
Use of bacteriophage Mu to isolate deletions in the his-nif region of Klebsiella pneumoniae
Authors: Bachhuber M , Brill W J , Howe M M
Published: January 2020

Klebsiella pneumoniae M5a1 is naturally resistant to infection by bacteriophage Mu. Mutants of K. pneumoniae sensitive to Mu infection were isolated and found to support both lytic and lysogenic development of Mu. K. pneumoniae lysogens containing a heat-inducible Mu prophage integrated in his were isolated. Strains carrying deletions extending from his into nif were obtained after heat treatment of these lysogens. Such deletions should be useful for determining the map order and cistronic organization of the nif genes.
Role and location of "protease I" from Escherichia coli
Authors: Kowit J D , Choy W N , Champe S P , Goldberg A L
Published: January 2020

Pacaud and Uriel described an enzyme from Escherichia coli ("protease I") that hydrolyzes acetyl phenylalanine naphthyl ester (APNE). We examined the possible involvement of this enzyme in intracellular protein degradation, its subcellular distribution, and its proteolytic activity. Although the APNE-hydrolyzing activity is localized primarily in the periplasm, proteolytic activity against casein was found in the periplasm, membrane, and cytoplasm with similar specific activities. The APNE-hydrolyzing enzyme did not appear to contribute to the proteolytic activity of the periplasm. A mutant deficient in APNE-hydrolyzing activity lacked all activity in the periplasm but showed a slight percentage of residual activity in the cytoplasm. Extracts of such cells were normal in their ability to hydrolyze casein. The mutant was indistinguishable from wild-type cells in its rate of protein degradation during growth or glucose starvation and in the ability to rapidly degrade puromycin-containing polypeptides. Nitrogen starvation, which increased protein breakdown severalfold, affected neither the total amount nor the distribution of APNE-hydrolyzing activity. The mutant showed no defect in its ability to cleave small phenylalanine-containing peptides released during protein degradation. The mutant and wild-type cells are equally able to hydrolyze exogenously supplied phenylalanyl peptides. These experiments suggest that the APNE-hydrolyzing enzyme is not required for protein degradation and that "protease I" is probably not a protease.
Isolation and characterization of Escherichia coli K-12 F- mutants defective in conjugation with an I-type donor
Authors: Havekes L , Tommassen J , Hoekstra W , Lugtenberg B
Published: January 2020

Escherichia coli K-12 F- mutants defective in conjugation with an I-type donor (ConI-) were isolated and characterized. These mutants are specific in that they are conjugation proficient with other types of donor strains. They have an altered susceptibility to phages and detergents. Chemical analysis of the cell envelopes of mutant strains has shown that the lipopolysaccharide (LPS) is altered and that one major outer-membrane protein is absent. Conjugation experiments in which LPS from wild-type cells was added to a mating mixture, made up with wild-type donor and recipient cells, showed inhibition in transconjugant formation when an I-type donor, but not an F-type donor, was used. This strongly suggests that LPS of the recipient cell is directly involved in the ability to mate with an I-type donor but not with an F-type donor. The mutations are located in the 78- to 82-min region of the E. coli map, with one exception where the mutation maps near or in the galactose operon.
Plasmid-determined resistance to tellurium compounds
Authors: Summers A O , Jacoby G A
Published: January 2020

Transferable plasmids in gram-negative bacteria that confer resistance to potassium tellurite or tellurate were found. This re-istance was distinct from resistance to mercury, silver, or arsenic compounds and was unrelated to antibiotic resistance. In Escherichia coli, plasmids determine a 100-fold increase in the minimal inhibitory concentration for tellurite and a 10-fold increase in tellurate resistance. Many, but not all, of the plasmids belong to incompatibility group S. In Pseudomonas aeruginosa, tellurium resistance is specifically associated with incompatibility group P-2 and involves a 5- to 10-fold increase in tellurite or tellurate resistance.
Biochemical study of the relationship of extracellular glucan to adherence and cariogenicity in Streptococcus mutans and an extracellular polysaccharide mutant
Authors: Johnson M C , Bozzola J J , Shechmeister I L , Shklair I L
Published: January 2020

A mutant of Streptococcus mutans, GS-5, which differed in extracellular polysaccharide (EPS) produced from sucrose, was used to study the role of EPS in the production of dental caries. The mutant proved to be identical to the parent strain in sugar fermentation, growth rate, and serotype. Strain GS-5 synthesized an EPS, which in electron micrographs appeared to be of fibrillar structure, whereas the mutant produced no fibrillar material but only a globular EPS. Analysis of the EPS revealed that about 30% of the glucose units in the GS-5 polymer carried (1-3)-like bonds either as branch points or as part of the linear backbone and that the mutant material contained only about 3% of these linkages. When grown in sucrose broth, the proportion of the mutant culture adherent to the glass vessel was dramatically less than that of the parent strain. Caries scores produced in conventional rats by the mutant were significantly lower than those obtained with the parent strain. Since the only difference discovered between strain GS-5 and the mutant was the inability of the mutant to synthesize either a fibrillar EPS or an EPS with more than about 3% (1-3)-like linkages, it was concluded that the fibrillar EPS of strain GS-5 contained about 30% (1-3)-like linkages and was necessary for adherence of the bacteria to surfaces and for production of dental caries in test animals.
Number of mutations required to evolve a new lactase function in Escherichia coli
Authors: Hall B G
Published: January 2020

The frequency of mutation of the ebgAo allele to ebgA+ was compared with the frequency of mutation of strA+ to strA-. The observation that both spontaneous and ethyl methane sulfonate-induced mutations to ebgA+ occurred more frequently than mutations to strA- suggests that ebgA+ mutants arise as the result of single-point mutations.
Relationship between changes in the translational apparatus and actinomycin production in Streptomyces antibioticus
Authors: Jones G H
Published: January 2020

As previously reported (G. H. Jones, 1975), transfer ribonucleic acids (tRNA's) and ribosomes from actinomycin-producing cultures of Streptomyces antibioticus show a decreased ability to function in aminoacylation and translation as compared with the corresponding components from younger cells. Further, specific changes in the isoacceptor patterns are revealed when tRNA's from actinomycin-producing cells are compared with those of younger cells by reverse- phase column chromatography. A specific glycyl-tRNA species is eliminated from the reverse-phase profile of tRNA's from actinomycin-producing S. antibioticus cells as compared with younger cells. Changes in isoacceptor patterns were also observed for the amino acids methionine, valine, phenylalanine, and leucine. Actinomycin synthesis was inhibited by growing S. antibioticus cells in the presence of alpha-methyl-DL-tryptophan. Inhibition of actinomycin synthesis reversed the changes in tRNA observed in normally grown control cultures, although it had no demonstrable effect on the growth of the cells. Thus, tRNA from 48-h-old, alpha-methyl-tryptophan-grown cells had amino acid acceptor activity that was equal to or greater than that of tRNA from 12-h-old, normally grown cells. Similarly, the reverse-phase chromatographic pattern for glycyl-tRNA's from 48-h-old, alpha-methyl-tryptophan-grown cells was identical to that of the glycyl-tRNA's from 12-h-old, normally grown cells. In contrast, the ability of ribosomes from 48-h-old, alpha-methyl-tryptophan-grown cells to function in polypeptide synthesis in vitro was essentially identical to that of 48-h-old, normally grown cells. Ribosomes from 12-h-old, normally grown cells were severalfold more active in in vitro polypeptide synthesis.
Biochemical localization of the alkaline phosphatase of Bacillus licheniformis as a function of culture age
Authors: Glynn J A , Schaffel S D , McNicholas J M , Hulett F M
Published: January 2020

Biochemical localization of the enzyme as a function of age of cell culture showed the alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) activity of Bacillus licheniformis MC14 predominantly in the particulate cell fraction in early- and mid-log cells. However, in late-log and stationary cells, increasing amounts of activity were found in the soluble fraction of lysed cells. Upon protoplast formation of these cells, the activity was released into the soluble fraction. No alkaline phosphatase activity was found in either the cytoplasmic fraction or in the cell medium during any phase of cell growth. The soluble fraction released on protoplast formation that contained alkaline phosphatase activity showed immunological cross-reactivity with antibody to the purified heat--salt-solubilized membrane alkaline phosphatase (F. M. Hulett-Cowling and L. L. Campbell, 1971). Theparticulate membrane fraction containing a firmly associated alkaline phosphatase also showed similar cross-reactivity. Further, the effectiveness of nonionic detergents, ionic detergents, bile salts, and various concentrations of magnesium and sodium as solubilizing agents for this membrane-bound alkaline phosphatase was investigated. Hexadecyl pyridinium chloride (0.03 M) and magnesium and sodium salts (above 0.2 M) were effective solubilizing agents. The substrate specificities of the various fractions were determined and compared to the substrate specificities of the purified membrane alkaline phosphatase.
Effects of incident light levels on photosynthetic membrane polypeptide composition and assembly in Rhodopseudomonas sphaeroides
Authors: Takemoto J , Huang Kao M Y
Published: January 2020

Cells of Rhodopseudomonas sphaeroides were grown anaerobically with incident light levels ranging between 4,500 and 400 footcandles (ca. 48,420 and 4,304 lux). Cells grown with the higher light levels had lower contents of total bacteriochlorophyll and incorporated L-[U-14C]leucine into membrane protein at higher rates than cells grown with lower light levels. The former cells also contained relatively lower amounts of light-harvesting membrane polypeptides as compared with the latter cells. In contrast, the relative amounts of reaction center membrane polypeptides were approximately the same with varying incident light levels. The relative amounts of these membrane polypeptides were correlated with differences in rates of synthesis and assembly of the polypeptides into membrane by measuring the rates of incorporation of L-[U-14C]leucine into the membrane-bound polypeptides. No significant differences in rates of turnover of these polypeptides were detected under the varying incident light levels as measured in pulse-chase radioactive labeling experiments.
Carnitine Acetyltransferase: Candidate for the Transfer of Acetyl Groups Through the Mitochondrial Membrane of Yeast
Authors: Kohlhaw Gunter B. , Tan-Wilson Anna
Published: January 2020

On the basis of its specific activity and its affinity for acetyl-coenzyme A, carnitine acetyltransferase appears to be the most likely candidate for acetyl group transfer out of yeast mitochondria.