bluuebunny/crossref_metadata_2025 huggingface dataset:
Manganese requirement of phosphoglycerate phosphomutase and its consequences for growth and sporulation of Bacillus subtilis
Authors: Oh Y K , Freese E
Published: January 2020

In the absence of manganese, rapidly metabolizable carbohydrates such as glucose or glycerol are not completely metabolized by Bacillus subtilis growing in a nutrient sporulation medium: 3-phosphoglyceric acid (3PGA) accumulates inside the cells, growth stops at a low cell titer, and normal sporulation remains suppressed (no prespore septa). Upon the addition of manganese, 3PGA disappears, growth resumes, and normal sporulation takes place. These effects results from a specific manganese requirement of phosphoglycerate phosphomutase which catalyzes the interconversion of 3PGA and 2-phosphoglyceric acid (2PGA). Other metal ions cannot replace manganese, for which the enzyme has an apparent Km of 0.22 mM.
Regulation of molybdate transport by Clostridium pasteurianum
Authors: Elliott B B , Mortenson L E
Published: January 2020

The regulation of the molybdate (MoO42-) transport activity of Clostridium pasteurianum has been studied by observing the effects of NH3, carbamyl phosphate, MoO42-, and chloramphenicol on the ability of cells to take up MoO42-. Compared with cells fixing N2, cells grown in the presence of 1 mM NH3 are greater than 95% repressed for MoO42- transport. Uptake activity begins to increase just before NH exhaustion (under Ar or N2) and continues to increase throughout the lag period as cells shift from NH3-growing to N2-fixing conditions. When cells are shifted from N2-fixing to NH3-growing conditions the transport activity per fixed number of cells decreases by increase of bells in absence of transport synthesis. Carbamyl phosphate (greater than or equal to 15 mM) but not NH3 inhibits 58% of the in vitro uptake activity. When 1 mM carbamyl phosphate is added just before the exhaustion of NH3, the transport activity, measured 2 h later, is 100% repressed. Cells grown in the presence of high MoO42- (1mM) are 80% repressed for MoO42- transport. Synthesis of the MoO42- transport system is also completely stopped when chloramphenicol (300 mug/ml) is added just before the exhaustion oNH 3 from the medium. These findings demonstrate that the ability of cells to transport MoO42- is dependent upon new protein synthesis and can be repressed by high levels of substrate. The regulation of MoO42- uptake by NH3 or carbamyl phosphate closely parallels the regulation of nitrogenase activity. Activity of neither nitrogenase component (Fe protein or MoFe protein) was detected even 3 h after the exhaustion of the NH3 if either MoO42- was absent or if WO42- was present in place of MoO42-. The duration of the diauxic lag increases with decreasing concentration of MoO42- in the medium. If no MoO42- is present the lag continues indefinitely. If MoO42- is added late in the lag period, growth under N2-fixing conditions resumes but only after a normal induction period.
Purification of properties of dihydroorotase, a zinc-containing metalloenzyme in Clostridium oroticum
Authors: Taylor W H , Taylor M L , Balch W E , Gilchrist P S
Published: January 2020

Dihydroorotase +4,5-L-dihydro-orotate amidohydrolase [EC 3.5.2.3]), which catalyzes the reversible cyclization of N-carbamyl-L-aspartate to L-dihydroorotate, has been purified from orotate-grown Clostridium oroticum. The enzyme is homogeneous when subjected to polyacrylamide gel electrophoresis and is stable at pH 7.6 in 0.3 M NaCl containing 10 muM ZnSO4. The enzyme has a molecular weight of approximately 110,000. Sodium dodecyl sulfate gel electrophoresis, using three different buffer systems, indicated the enzyme is composed of two subunits, each having a molecular weight of 55,000. Dihydroorotase is shown by atomic absorption spectroscopy to be a zinc-containing metalloenzyme with 4 g-atoms of zinc per 110,000 g of protein. The pH optima for the conversion of N-carbamyl-L-aspartate to L-dihydroorotate and for L-dihydroorotate to N-carbamyl-L-aspartate are pH 6.0 and 8.2, respectively. The Km values for N-carbamyl-L-aspartate and for L-dihydroorotate are 0.13 and 0.07 mM, respectively. Inhibitor studies indicate that zinc may be involved in the catalytic activity of the enzyme.
Influence of amino acids on the growth of Bacteroides melaninogenicus
Authors: Miles D O , Dyer J K , Wong J C
Published: January 2020

Addition of individual amino acids to a Trypticase-yeast extract-hemin medium affected growth rates and final yields of an asaccharolytic strain and a saccharolytic strain of Bacteroides melaninogenicus. L-Aspartate or L-asparagine produced maximal growth enhancement for both strains. L-[14C]aspartate was fermented by resting cells of the asaccharolytic strain. L-Cysteine or L-serine also enhanced growth for the saccharolytic strain. However, growth of the saccharolytic strain was inhibited by L-lysine, L-glutamate, L-glutamine, L-isoleucine, L-leucine, and L-proline; growth of the asaccharolytic strain was inhibited by DL-valine and L-serine. Both strains were inhibited by L-histidine, DL-methionine, L-tryptophan, L-arginine, and glycine.
Method for the isolation of the replication region of a bacterial replicon: construction of a mini-F'kn plasmid
Authors: Lovett M A , Helinski D R
Published: January 2020

A purified fragment of deoxyribonucleic acid (DNA) that determines resistance to kanamycin and is incapable of self-replication was used to select a self-replicating fragment from an EcoRI endonuclease digest of the sex factor F'lac. This F'lac fragment, exhibiting a molecular weight of 6 X 10(6), carries the genes essential for maintenance of the F replicon in Escherichia coli cells. The constructed mini-F'km plasmid also retains the incompatibility properties of the parent F'lac plasmid. Large amounts of the kanamycin resistance fragment of a molecular weight of 4.5 X 10(6) with an EcoRI-cleaved, self-replicating derivative of colicinogenic plasmid E1 that has a molecular weight of 2.2 X 10(6), The recombinant plasmid is able to replicate extensively in E. coli in medium containing chloramphenicol, and, therefore, large quantities of this plasmid DNA can be obtained. The substantial difference in size between the two fragments in the recombinant plasmid greatly facilitates their separation by preparative agarose gel electrophoresis.
Constitutive and repressivle enzymes of the common pathway of aromatic biosynthesis in Escherichia coli K-12: regulation of enzyme synthesis at different growth rates
Authors: Tribe D E , Camakaris H , Pittard J
Published: January 2020

Synthesis of five of the enzymes of the common pathway of aromatic biosynthesis has been shown to be unaffected by either the aromatic amino acids--the product of the first reaction (3-deoxy-D-arabinoheptulosonic acid-7-phosphate) or the product of the last reaction (chorismate)--or by the state of regulator gene loci tyrR. On the other hand, the rate of synthesis of these enzymes, and of several other enzymes for which repression control was inactive because of mutations in relevant regulator genes, was found to change with growth rate. These changes were found to correlate at faster growth rates than those observed in glucose minimal medium with the alterations in the relative frequencies of the corresponding structural genes which occur at these growth rates. It was found that when wild-type cells were grown at these faster growth rates in medium lacking the aromatic amino acids, complete derepression of the tyrosine-inhibitable 3-deoxy-D-arabinoheptulosonic acid-7-phosphate synthetase occurred, in strong contrast to the situation when wild-type cells are grown in glucose minimal medium.
Synthesis of omega-alicyclic fatty acids from cyclic precursors in Bacillus subtilis
Authors: Dreher R , Poralla K , König W A
Published: January 2020

A mutant of Bacillus subtilis synthesizes a variety of omega-alicyclic fatty acids when fed with the respective alicyclic carboxylic acids. These fatty acids are: omega-cyclopropane, omega-cyclobutane, omega-cyclopentane, omega-cyclohexane, and omega-cyclohexene fatty acids. These unusual fatty acids did not lead to an inhibition of growth at 37 degrees C and pH 7. The selective advantage of these fatty acids under extrene conditions was studied in comparison with the acidophilic, thermophilic bacterium B. acidocaldarius, which normally contains a high proportion of omega-cyclohexane fatty acids.
Motility as a morphogenic character in the genus Arthrobacter
Authors: Stanlake G J , Clark J B
Published: January 2020

Motility in Arthrobacter atrocyaneus, A. citreus, and A. simplex was found to correlate with the morphogenic cycle of these organisms. The percentage of the A. atrocyaneus and A. simplex populations that were flagellated at a given time during the growth cycle differed significantly from that of the normorphogenic Pseudomonas aeruginosa population. Flagellation in A. atrocyaneus was shown to be dependent upon the morphogenic cycle rather than upon growth. The commitment to flagellar synthesis in A. atrocyaneus was found to occur only after induction to the rod morphology. Flagellar synthesis in A. atrocyaneus was shown to be restricted to only a small segment of the morphogenic cycle.
Deoxyribonucleic acid polymerase from the extreme thermophile Thermus aquaticus
Authors: Chien A , Edgar D B , Trela J M
Published: January 2020

A stable deoxyribonucleic acid (DNA) polymerase (EC 2.7.7.7) with a temperature optimum of 80 degrees C has been purified from the extreme thermophile Thermus aquaticus. The enzyme is free from phosphomonoesterase, phosphodiesterase and single-stranded exonuclease activities. Maximal activity of the enzyme requires all four deoxyribonucleotides and activated calf thymus DNA. An absolute requirement for divalent cation cofactor was satisfied by Mg2+ or to a lesser extent by Mn2+. Monovalent cations at concentrations as high as 0.1 M did not show a significant inhibitory effect. The pH optimum was 8.0 in tris(hydroxymethyl)aminomethane-hydrochloride buffer. The molecular weight of the enzyme was estimated by sucrose gradient centrifugation and gel filtrations on Sephadex G-100 to be approximately 63,000 to 68,000. The elevated temperature requirement, small size, and lack of nuclease activity distinguish this polymerase from the DNA polymerase of Escherichia coli.
Electron microscope studies of conditional spore cortexless mutants of Bacillus sphaericus
Authors: Imae Y , Strominger M B , Strominger J L
Published: January 2020

Spore cortex of conditional cortexless mutants of Bacillus sphaericus 9602 was not detectable by electron microscopy unless the medium was supplemented with meso-alpha,epsilon-diaminopimelic acid during sporulation. Other spore structures appeared normal. Spore shape was quite irregular in the absence of meso-alpha,epsilon-diaminopimelic acid.
Genetic Map Position of the
pdxH
Gene in
Escherichia coli
Authors: Shimizu Sakayu , Dempsey Walter B.
Published: January 2020

The gene for pyridoxine phosphate oxidase,
pdxH
, is located 1.2 min beyond
aroD
, proximal to
trp
.
Influence of secretory immunoglobulin A and purified secretory component on dextran-sucrase activity of Streptococcus mutans
Authors: Cole J S , Clark G E , Wistar R
Published: January 2020

The net stimulation of dextransucrase EC 2.4.1.5) activity from Streptococcus mutans HS6 by dextran, secretory immunoglobulin A, or secretory component was investigated. Approximately equal stimulation resulted from treatment with these three components.
Iron-chelating compound from Mycobacterium avium
Authors: McCullough W G , Merkal R S
Published: January 2020

A iron-chelating monohydroxamate was isolated from cultures of Mycobacterium avium grown on an iron-limiting medium. The hydroxyamate metabolite was characterized by chemical degradation and spectral measurements as L-alpha-asparaginyl-L-alpha-(N-hydroxy)-asparagine.
Prediction of the rate of glucose utilization from cellular levels of glucose 6-phosphate and fructose 1,6-diphosphate in Escherichia coli
Authors: Dietzler D N , Leckie M P , Crimmins D L , Ungar J M , Sternheim W L
Published: January 2020

A comprehensive equation, upsilon = VM/[1 + (A0.5/Fru-P2)n] [ 1 + (Glc-6-P/I0.5)], has been proposed to represent the quantitative interrelationships between the rate of glucose utilization and the levels of glucose-6-phosphate and fructose-1,6-diphosphate in the intact Escherichia coli cell. This comprehensive equation was derived from empirical equations that describe the relationship between the rate of glucose utilization and one of these hexose phosphates in metabolic situations where the other hexoses phosphate was not altered. In the experiments described in this report, treatment of nitrogen (NH4+)-starved cultures of E. coli W4597 (K) with various concentrations of sodium azide altered the levels of both hexose phosphates as well as the rate of glucose utilization. In each case the observed rate and the rate predicted by the comprehensive equation agreed closely, substantiating the validity of this comprehensive relationship as a quantitative indicator of metabolic events in the intact cell. The mechanism of metabolic regulation that is represented by this equation is discussed in light of the cellular levels of adenosine 5'-triphosphate and phosphoenolpyruvate observed in these experiments.
Acceptance and transfer of R-factor RP1 by members of the "herbicola" group of the genus Erwinia
Authors: Gibbins L N , Bennett P M , Saunders J R , Grinsted J , Connolly J C
Published: January 2020

The R-factor RP1 was transferred by conjugation from Pseudomonas aeruginosa PAO12r(RPI) to various strains of Erwinia herbicola and to one strain of Erwinia stewartii. The exconjugate strains had minimum inhibitory concentration values for carbenicillin, kanamycin, neomycin, and tetracycline somewhat lower than the corresponding values for the pseudomonad RP1 donor strain. The biochemical characteristics of the exconjugant strains displayed minor variation in some instances from those of the corresponding R- strains. Sensitivity of the RP1+ strains to the RP1-specific bacteriophages PRD1 and PRR1 varied from an efficiency of plating [compared with P. aeruginosa PA067(RP1)] of 0 [E. herbicola Y46(RP1)] to 133 [E. herbicola Y190(RP1)] and 148 [E. stewartii SS104R(RP1)] for PRD1, and from 0 [E. herbicola Y46(RP1)] to 0.0002 [E. herbicola Y185(RP1)] and 18.4 [E. stewartii SS104R(RP1)] for PRR1. The phage-resistant strain E. herbicola Y46(RP1), would donate, by conjugation, the R-factor to E. herbicola Y46rifr, P, aeruginosa PAT900, or Escherichia coli UB1005 only at extremely low frequencies, if at all. Transformation of E. coli JC7620 by covalently closed circular DNA from E. herbicola Y46(RP1) gave and E. coli R+ strain exhibiting the expected antibiotic resistance pattern and having the ability to donate RP1 by conjugation. It is suggested (i) that some strains of E. herbicola RP1 either do not produce RP1 pili or produce defective pili, and (ii) that sensitivity to the bacteriophages PRD1 and PRR1 is not a suitable means of diagnosing the presence RP1 in E. herbicola strains.
Convenient method for detecting 14CO2 in multiple samples: application to rapid screening for mutants
Authors: Tabor H , Tabor C W , Hafner E W
Published: January 2020

A procedure is presented for the rapid screening of bacterial colonies to detect mutants unable to produce 14CO2 from a labeled precursor. The method is especially useful for mass screening for mutants that cannot be easily detected by their phenotypic characteristics.
Execution times of macromolecular synthetic processes involved in the induction of allophanate hydrolase at 15 degrees C
Authors: Bossinger J , Cooper T G
Published: January 2020

We have observed that transcription, involved in production of allophanate hydrolase, is completed 2.5 min after the addition of inducer at 15 degrees C. The rna1 gene product must be functional up unti 10 min; protein synthesis is initiated at 20 min and is terminated by 24 min. Two minutes later, active enzyme appears. The results confirm our earlier observations and eliminate any uncertainty that might have clouded identification of the time within the lag period that is occupied by ribonucleic acid synthesis.
Resporulation of outgrowing Bacillus subtilis spores
Authors: Keynan A , Berns A A , Dunn G , Young M , Mandelstam J
Published: January 2020

Germinated spores of Bacillus subtilis were incubated in outgrowth medium and tested periodically for capacity to sporulate when suspended in sporulation medium. Concurrent measurements were made of deoxyribonucleic acid (DNA) content and numbers of cell division septa and nucleoids. Sporulation potential is shown to reach a peak at about 110 min at which time the chromosomes are probably well into the second round of replication. Experiments with nalidixic acid show that sporulation potential can be generated in the outgrowth medium even when DNA synthesis is largely prevented. Further experiments show that nalidixic acid apparently does not prevent the formation of DNA initiation complexes, which can subsequently function after resuspension in the sporulation medium. The results support those previously obtained with a temperature-sensitive DNA mutant which indicated that sporulation could only be induced at a specific stage of chromosome replication, and then only if the cells are in a state of nutritional "step-down".
Derepressed synthesis of cellulase by Cellulomonas
Authors: Stewart B J , Leatherwood J M
Published: January 2020

A Cellulomonas sp. was isolated from the soil which hydrolyzed cellulose, as shown by clear-zone formation on cellulose agar medium. Catabolite repression of cellulase synthesis occurred when moderate levels of glucose were added to the medium. A stable mutant that no longer exhibits catabolite repression was produced through treatment of the wild-type organism with N-methyl-N'-nitro-N-nitrosoguanidine. Both enzyme concentration and specific activity, as determined by the rate of hydrolysis of carboxymethylcellulose, were greater with the mutant than with the wild-type organism under various test conditions. The wild type had no measurable cellulase activity when grown in the presence of either 1.0% glucose or cellobiose. Cellobiose, but not glucose, inhibited enzyme activity towards both cellulose and carboxymethylcellulose. Cellobiose, cellulose, and sophorose at low concentrations induced cellulase synthesis in both the wild-type and the mutant organism. Cellulase regulation appears to depend upon a complex relationship involving catabolite repression, inhibition, and induction.
Glycolytic and tricarboxylic acid cycle enzyme activities during intraperiplasmic growth of Bdellovibrio bacteriovorus on Escherichia coli
Authors: Hespell R B
Published: January 2020

Selected enzyme activities were measured in extracts of the total cell pellets obtained at various times during aerobic intraperiplasmic growth of Bdellovibrio bacteriovorus 109J on anaerobically grown Escherichia coli substrate cells. Initially, the glycolytic enzyme activities were associated with the input of E. coli and the tricarboxylic acid cycle enzyme activities with the input of bdellovibrios. During the first 90 min of Bdellovibrio development, the glycolytic activities declined about 25 to 60%, whereas the tricarboxylic acid cycle activities increased about 10%. Between 110 and 180 min, the glycolytic activities decreased to trace levels and tricarboxylic acid cycle activities increased about 50 to 90%. Both bdellovibrio cell extracts and the cell-free growth menstruum (obtained after bdellovibrio growth on E. coli) caused the inactivation of glycolytic enzymes in E. coli extracts.
Role of 4-aminobutyrate aminotransferase in the arginine metabolism of Pseudomonas aeruginosa
Authors: Voellym R , Leisinger T
Published: January 2020

4-Aminobutyrate aminotransferase (GABAT) from Pseudomonas aeruginosa was purified 64-fold to apparent electrophoretic homogeneity from cells grown with 4-aminobutyrate as the only source of carbon and nitrogen. Purified GABAT catalyzed the transamination of 4-aminobutyrate, N2-acetyl-L-ornithine, L-ornithine, putrescine, L-lysine, and cadaverine with 2-oxoglutarate (listed in order of decreasing activity). The enzyme is induced in cells grown on 4-guanidinobutyrate, 4-aminobutyrate, or putrescine as the only carbon and nitrogen source. Cells grown on arginine or on glutamate contained low levels of the enzyme. The regulation of the synthesis of GABAT as well as the properties of the mutant with an inactive N2-acetyl-L-ornithin 5-aminotransferase suggest that GABAT functions in the biosynthesis of arginine by convertine N2-acetyl-L-glutamate 5-semialdehyde to N2-acetyl-Lornithine as well as in catabolic reactions during growth on putrescine or 4-guanidinobutyrate but not during growth on arginine.
Complexity of the ultraviolet mutation frequency response curve in Escherichia coli B/r: SOS induction, one-lesion and two-lesion mutagenesis
Authors: Doudney C O
Published: January 2020

Three distinct sections of the ultraviolet mutation frequency response (MFR) curve toward tryptophan prototrophy have been demonstrated in Excherichia coli B/r WP2 trp thy and its uvrA derivative in log-phase growth in minimal medium. The initial section, which appears fluence-squared, may reflect the necessity, if mutation is to result, for induction of two lesions, one located within the potentially mutated genetic locus and the other damaging deoxyribonucleic acid replication and resulting in inducation of the error-prone SOS repair function. A second linear section is ascribed to the continued induction, after exposure above that sufficient for complete SOS expression, of isolated lesions which lead to mutation in potentially mutated loci. The third section demonstrates an increased rate of mutagenesis and suggests the induction of two lesions in proximity which result in additional mutations. Split-exposure studies support the inducible nature of the SOS function and suggest that mutation frequency decline (MFD) is due to exicion resulting from or related to the prevention of SOS induction by inhibition of protein synthesis. Preirradiation tryptophan starvation of the uvr+ strain for 30 min decrease MFR in the first and second sections of the curve. Reduction of MFR in the third section requires more prestarvation time and is blocked by nalidixic acid. The decreased MFR of the first and second sections ascribed to promotion of postirradiation MFD based on excision and that of third section to completion of the chromosome during the prestarvation period.
Adenine methylation of Okazaki fragments in Escherichia coli
Authors: Marinus M G
Published: January 2020

In Escherichia coli polA lig-4 bacteria, the moles percent 6-methyladenine content of 10S deoxyribonucleic acid (Okazaki fragments) is 0.96 compared with 1.4 for bulk desoxyribonucleic acid.
Mutations in Prophage φ11 That Impair the Transducibility of Their
Staphylococcus aureus
Lysogens for Methicillin Resistance
Authors: Cohen Sidney , Sweeney Helen M. , Basu Sandip K.
Published: January 2020

Methicillin resistance (
mec
) is not transduced into
Staphylococcus aureus
8325-4, but is transduced into this host after it has been lysogenized with phage φ11 and has acquired the penicillinase plasmid pI524 by a separate transduction (Cohen and Sweeney, 1970, 1973). Strain 8325-4 is competent for transformation of typical plasmid or chromosomal markers and for
mec
only if it is lysogenic for φ11 or a related prophage (Sjöström et al., 1974, 1975). A mutant strain of φ11 that was temperature sensitive (Ts) for vegetative multiplication did not mediate competence for transformation of its 8325-4 lysogen if the lysogen had been grown at a nonpermissive temperature (Sjöström and Philipson, 1974). We isolated four Ts mutants of φ11 that did not mediate transducibility of their 8325-4(pI524) lysogens for
mec
after growth at nonpermissive temperatures (40 to 42°C). Transduction of typical plasmid or chromosomal markers was not affected. These φ11-Ts mutants mediated normal competence of their lysogens for transformation of a tetracycline resistance plasmid. Similarly, φ11-Ts mutants that rendered their lysogens temperature sensitive for transformation did not depress the frequency of transduction of
mec
. These two types of φ11-Ts mutants fell into two different genetic complementation groups that differed in the physiology of deoxyribonucleic acid synthesis and in the time of expression of the mutations during a single-burst growth cycle at a nonpermissive temperature. A virulent mutant of φ11, which plaqued with 100% efficiency on 8325(φ11), also failed to condition strain 8325-4 for transducibility of
mec
but retained the ability to confer competence for transformation of a tetracycline resistance plasmid. Different genetic loci and physiological functions are involved in φ11 mutations that affect transducibility of
mec
and those that affect competence for transformation of markers generally in
S. aureus
8325-4.
Biosynthesis of bacterial glycogen: genetic and allosteric regulation of glycogen biosynthesis in Salmonella typhimurium LT-2
Authors: Steiner K E , Preiss J
Published: January 2020

Structural gene mutants of the glycogen biosynthetic enzymes adenosine diphosphate glucose pyrophosphorylase (glgC) and glycogen synthase (glgA) were isolated and partially characterized. The cotransduction frequencies of these genes with the aspartic semialdehyde dehydrogenase (asd) and glycerol-3-phosphate dehydrogenase (glpD) genes suggested the unambiguous gene order of glpD glgA glgC asd. The results of the three-factor cross glpD- glgA- glgC+ X glpD+ glgA+ glgC- were consistent with the proposed order. A simultaneous and approximately equivalent derepression of the glgC, glgA, and glgB (branching enzyme) gene products was observed in the late logarithmic-early stationary phase of growth on enriched media. These results are consistent with the coordinately regulated synthesis of the three glycogen biosynthetic enzymes in Salmonella typhimurium.
Biosynthesis of the outer membrane receptor for vitamin B12, E colicins, and bacteriophage BF23 by Escherichia coli: kinetics of phenotypic expression after the introduction of bfe+ and bfe alleles
Authors: Bassford P J , Kadner R J , Schnaitman C A
Published: January 2020

The bfe locus codes for the cell surface receptor for vitamin B12, the E colicins, and bacteriophage BF23 in the Escherichia coli outer membrane. When the bfe+ allele, which is closely linked to the argH locus, was introduced into an argH bfe recipient by conjugation, arg+ recombinant cells rapidly and simultaneously acquired sensitivity to colicin E3 and phage BF23. In the reciprocal experiment introducing bfe into an argH bfe+ recipient, it was found that colicin E3-resistant, arg+ cells began to appear shortly after the arg+ recombinant population began to divide. This was far earlier than would have been predicted on the basis of 220 receptors per haploid cell. Moreover, there was a lag between the appearance of colicin resistance and the appearance of resistance to killing by phage BF23, and hence a period of time during which some arg+ recombinant cells were sensitive to the phage but resistant to the colicin. Colicin E3 added to cells during this period of time protected against phage killing, indicating that the colicin-resistant cells still had receptors capable of binding colicin on their surface. The modification of the phenotypic expression of colicin and phage resistance by inhibitors of deoxyribonucleic acid, ribonucleic acid, and protein synthesis was also investigated. The results obtained indicate that the receptor protein coded for by the bfe locus can exist on the cell surface in several different functional states.
Interaction of cytoplasmic membrane and ribosomes in Escherichia coli: spectinomycin-induced disappearance of membrane protein I-19
Authors: Mizuno T , Yamagata H , Mizushima S
Published: January 2020

Incubation of Escherichia coli with spectinomycin caused the disappearance of a major protein from the cytoplasmic membrane. This protein, called "I-19", was not a ribosomal protein. Its disappearance was not a result of the direct action of spectinomycin on the cytoplasmic membrane, but a result of its action on ribosomes. The disappearance was specifically induced by spectinomycin, and other antibiotics such as neomycin, erythromycin, and chloramphenicol had no effect. Although growth was not required for spectinomycin-induced disappearance of protein I-19 from the cytoplasmic membrane, the disappearance was not observed under conditions where protein synthesis was inhibited completely either by the addition of chloramphenicol or by cooling in ice. It is suggested that at least some ribosomes interact with the cytoplasmic membrane and that a modification of the mode of interaction through the action of spectinomycin on ribosomes caused the deletion of membrane protein I-19.
Isolation of a mutant TOL plasmid with increased activity and transmissibility from Pseudomonas putida (arvilla) mt-2
Authors: Nakazawa T , Yokota T
Published: January 2020

Strains with greater ability to dissimilate m-toluate were obtained from the wild-type Pseudomonas putida (arvilla) mt-2 that harbors the TOL plasmid. Increased growth of a mutant strain on aromatic substrates was coupled with simultaneous increase in the activity of metapyrocatechase, an enzyme coded by the TOL plasmid, without changing its catalytic properties. In the mutant and the wild-type strains, the inducer specificity and the induction kinetics of metapyrocatechase synthesis were the same, and a half-maximal effect of m-toluate on the enzyme synthesis was observed at 0.25 mM. Thus, the increased utilizability seen in a mutant strain appeared to be due to an increased quantity of the enzymes coded by the TOL plasmid. The properties of the mutant strain were dependent upon the mutation on the TOL plasmid but not on the chromosome mutation. Transfer experiments with a strain carrying the mutant TOL (TOL-H) or the wild-type TOL plasmid revealed that the TOL-H transfer was 1,000 times greater than that of the wild type.
Deoxyribonucleic acid sequence organization of a yeast plasmid
Authors: Livingston D M , Klein H L
Published: January 2020

Two-micrometer deoxyribonucleic acid (DNA), a circular plasmid of Saccharomyces cerevisiae, contains two nontandem repeated sequences which are inverted with respect to one another. These repeated sequences together account for 21% of the molecule length. Restriction endonuclease analysis and electron microscopy demonstrated the existence of two forms of 2-mum DNA differing in the orientation of the interstitial segments bounded by the inverted repeated sequences. The two forms of 2-mum DNA could result from an intramolecular reciprocal recombination between inverted repeat elements. A map containing the restriction endonuclease sites and the units of the inverted repeat has been constructed.
Presence of cytochrome c in Desulfomonas pigra
Authors: Sperry J F , Wilkins T D
Published: January 2020

Desulfomonas pigra, a gram-negative, nonmotile anaerobic, sulfate-reducing bacillus isolated from human feces, was found to have cytochrome c and a desulfoviridin-like pigment.
Accumulation of nucleotides by starved Escherichia coli cells as a probe for the involvement of ribonucleases in ribonucleic acid degradation
Authors: Cohen L , Kaplan R
Published: January 2020

The acid-soluble ribonucleic acid degradation products formed by Escherichia coli cells starved for a carbon source have been identified. They comprise oligonucleotides, nucleoside diphosphates, 5'- and 3'-nucleoside monophosphates, nucleosides, and free bases. The majority of these products are excreted phates, nucleosides, and free bases. The majority of these products are excreted into the medium, and only small and constant amounts are kept in the pool. During carbon starvation at elevated temperatures, mutants deficient in ribonuclease I do not form oligonucleotides and 3'-nucleoside monophosphates, and mutants that contain a modified form of polynucleotide phosphorylase do not accumulate nucleoside diphosphates. 5'-Nucleoside monophosphates do accumulate, however, in a mutant containing thermoabile ribonuclease II, under conditions where more than 95% of all enzyme activity had been destroyed. The data presented confirm the participation of ribonuclease I and polynucleotide phosphorylase in the final steps of ribonucleic acid degradation and indicate that an exonuclease forming 5'-nucleoside monophosphates is also involved.
Purification and properties of homoprotocatechuate 2,3-dioxygenase from Bacillus stearothermophilus
Authors: Jamaluddin M P
Published: January 2020

The enzyme 3,4-dihydroxyphenylacetate:oxygen 2,3-oxidoreductase (decyclizing) (homoprotocatechuate 2,3-dioxygenase) was purified from the thermophilic organism Bacillus stearothermophilus, grown with j-hydroxyphenylacetic acid as a source of carbon. The enzyme appeared to be homogeneous as judged by disc-gel electrophoresis and sedimentation equilibrium measurements. The average molecular weight determined by three independent procedures was 106,000; the protein was globular and was dissociated in sodium dodecyl sulfate to give a species of molecular weight 33,000 to 35,000. The enzyme was fairly stable on heating and showed maximal activity at about 57 degrees C. An Arrhenius plot of Km for homoprotocatechuate was concave upward, with a break at 32 degrees C; an increase in delta H above this temperature was compensated by lower values of --delta S. Several properties of this enzyme are contrasted with those reported for homoprotocatechuate 2,3-dioxygenase purified by other workers from Pseudomonas ovalis.
Synthesis of cell envelope components by anucleate cells (minicells) of Bacillus subtilis
Authors: Mertens G , Reeve J N
Published: January 2020

Minicells produced by Bacillus subtilis CU403 (divIVB1) are capable of mucopeptide biosynthesis as shown by the incorporation of L-alanine, D-alanine, and N-acetylglucosamine into trichloroacetic acid-precipitable material, which can be degraded to trichloroacetic acid-soluble material by lysozyme digestion. Incorporation of the precursors is sensitive to vancomycin and D-cycloserine and insensitive to chloramphenicol. Penicillin inhibits the incorporation of D- and L-alanine N-acetylglucosamine at concentrations in excess of 10 mug of penicillin per ml; however, minicells are insensitive to penicillin-induced lysis. The material synthesized in minicells from N-acetylglucosamine is not subject to turnover during a subsequent 6-h incubation period. [2-3H]glycerol is converted to a cold trichloroacetic acid-precipitable form by minicells. This synthesis is not inhibited by vancomycin, penicillin, D-cycloserine, or chloramphenicol. Fractionation of the material synthesized from glycerol into hot trichloroacetic acid-soluble material and chloroform/methanol-extractable material indicates that minicells convert glycerol into teichoic acid and lipid.
Selective inhibition of Bacillus subtilis sporulation by acridine orange and promethazine
Authors: Burke W F , Spizizen J
Published: January 2020

Two structurally similar compounds were found to inhibit sporulation in Bacillus subtilis 168. A dye, acridine orange, and an antischizophrenic drug, promethazine, blocked spore formation at concentrations subinhibitory to vegetative growth, while allowing synthesis of serine protease, antibiotic, and certain catabolite-repressed enzymes. The sporulation process was sensitive to promethazine through T2, whereas acridine orange was inhibitory until T4. The drug-treated cells were able to support the replication of phages phie and phi29, although the lytic cycles were altered slightly. The selective inhibition of sporulation by these compounds may be related to the affinity of some sporulation-specific genes to intercalating compounds.
Initiation of Bacillus spore germination by hydrostatic pressure: effect of temperature
Authors: Murrell W G , Wills P A
Published: January 2020

Suspensions of Bacillus cereus T, B. subtilis, and B. pumilus spores in water or potassium phosphate buffer were germinated by hydrostatic pressures of between 325 and 975 atm. Kinetics of germination at temperatures within the range of 25 to 44 degrees C were determined, and thermodynamic parameters were calculated. The optimum temperature for germination was dependent on pressure, species, suspending medium, and storage time after heat activation. Germination rates increased significantly with small increments of pressure, as indicated by high negative deltaV values of -230 +/- 5 cm3/mol for buffered B. subtilis (500 to 700 atm) and B. pumilus (500 atm) spores and -254 +/- 18 cm3/mol for aqueous B. subtilis (400 to 550 atm) spores at 40 degrees C and -612 +/- 41 cm3/mol for B. cereus (500 to 700 atm) spores at 25 degrees C. The ranges of thermodynamic constants calculated at 40 degrees C for buffered B. pumilus and B. subtilis spores at 500 and 600 atm and for aqueous B. subtilis spores at 500 atm were: Ea = 181,000 to 267,000 J/mol; deltaH = 178,000 to 264,000 J/mol; deltaG = 94,000 to 98,300 J/mol; deltaS = 264 to 544 J/mol per degree K. These values are consistent with the concept that the transformation of a dormant to a germinating spore induced by hydrostatic pressure involves either hydration or a reduction in the visocosity of the spore core and a conformational change of an enzyme.
Inhibition of Dictyostelium discoideum beta-glucosidase by purines
Authors: Parish R W
Published: January 2020

beta-Glucosidase of Dictyostelium discoideum is inhibited by purines in the following order: adenine greater than adenosine greater than 6-methylaminopurine greater than hypoxanthine greater than inosine greater than purine greater than guanosine. Adenine inhibits activity by 50% at 1 to 2 mM. The kinetics are complex because the enzyme is stimulated by substrate and inhibited by glucose.
Methionyl-transfer ribonucleic acid deficiency during G1 arrest of Saccharomyces cerevisiae
Authors: Unger M W
Published: January 2020

The mesl- mutants of Saccharomyces cerevisiae cease division and accumulate in the G1 interval of the cell cycle when deprived of methionine or shifted from 23 to 36 degrees C in the presence of methionine. Synchronous cell cycle arrest results from a deficiency of charged methionyl-transfer ribonucleic acid (methionyl-tRNAMet) as shown by direct measurement of the in vivo pools of methionine, S-adenosylmethionine, and methionyl-tRNAMet. The deficiency of methionyl-tRNAMet in these cells is the consequence of a lesion in a single gene, mes1. mes1 appears to be the structural gene for the methionyl-tRNA synthetase because some revertants of this mutation exhibited a thermolabile methionyl-tRNA synthetase in vitro. A sufficient hypothesis to explain these and previous results is that the control of cell division by S. cerevisiae in response to nutrient limitation is mediated through aminoacyl-tRNA or subsequent steps in protein biosynthesis.
Uptake of ferrienterochelin by Escherichia coli: energy dependent stage of uptake
Authors: Pugsley A P , Reeves P
Published: January 2020

The uptake of the siderophore-iron complex ferrienterochelin was found to be strongly dependent upon an energized membrane state, as demonstrated by its sensitivity to dinitrophenol, azide, and cyanide. Ferrienterochelin uptake may also be dependent upon phosphate bond energy, as indicated by sensitivity to arsenate and iodoacetic acid. Although the adenosine triphosphatase does not appear to be involved in this energy coupling mechanism, ferrienterochelin uptake was shown to be less dependent upon phosphate bond energy than was glutamine uptake. Sensitivity of ferrienterochelin uptake to osmotic shock was shown to be due to the release of a ferrienterochelin binding compound located in the outer membrane of the cells and probably identical to the colicin B receptor protein.
Localization of enzymes in Ureaplasma urealyticum (T-strain mycoplasma)
Authors: Masover G K , Razin S , Hayflick L
Published: January 2020

Ureaplasma urealyticum cells were lysed by osmotic shock or by digitonin. The membrane fraction contained four to ten times as much protein as the cytoplasmic fraction. These values are in large excess of those reported for classical mycoplasmas, suggesting that the Ureaplasma membrane fraction was heavily contaminated with proteins derived from the growth medium. The U. urealyticum urease activity was localized in the cytoplasmic fraction, whereas the adenosine triphosphatase activity was localized in the membrane fraction. Significant urease activity could be detected also in nonviable cells. Urea, at concentrations above 0.25 M, was mycoplasmastatic to Acholeplasma laidlawii, Mycoplasma hominis, and U. urealyticum, so that the Ureaplasma urease did not afford preferential protection against urea toxicity. The intracellular localization of the urease would be expected to release ammonia from urea in the cytoplasm. The ammonia will take up protons to become ammonium ions. It can be hypothesized that the intracellular NH4+ plays a role in proton elimination or acid-base balance, which might be coupled to an energy producing ion gradient and/or transport mechanisms.
Degradation of Escherichia coli beta-galactosidase fragments in protease-deficient mutants of Salmonella typhimurium
Authors: Miller C G , Zipser D
Published: January 2020

The degradation rates of several mutationally generated fragments of Escherichia coli beta-galactosidase were determined in wild-type strains of Salmonella typhimurium and in mutant Salmonella strains lacking several proteases and peptidases. Three termination fragments (produced by lacZ545, lacZ521, and lacZX90) and one internal reinitiation (restart) fragment [lacZpi(1)] are degraded in wild-type Salmonella strains at the same rates observed in wild-type Escherichia coli strains. Mutations that lead to loss of peptidases N, A, B, P, and Q or to loss of protease I or II do not affect the decay rates of any of these fragments. In addition, all of these peptidases and proteases are present in E coli mutants carrying deg mutations (deg mutations are known to stabilize beta-galactosidase fragments). Apparently, none of the proteases and peptidases that are currently accessible to direct genetic analysis plays a role in the early steps of the degradation of protein fragments.
Escherichia coli mutants deficient in the aspartate and aromatic amino acid aminotransferases
Authors: Gelfand D H , Steinberg R A
Published: January 2020

Two new mutations are described which, together, eliminate essentially all the aminotransferase activity required for de novo biosynthesis of tyrosine, phenylalanine, and aspartic acid in a K-12 strain of Escherichia coli. One mutation, designated tyrB, lies at about 80 min on the E. coli map and inactivates the "tyrosine-repressible" tyrosine/phenylalanine aminotransferase. The second mutation, aspC, maps at about 20 min and inactivates a nonrespressible aspartate aminotransferase that also has activity on the aromatic amino acids. In ilvE- strains, which lack the branched-chain amino acid aminotransferase, the presence of either the tyrosine-repressible aminotransferase or the aspartate aminotransferase is sufficient for growth in the absence of exogenous tyrosine, phenylalanine, or aspartate; the tyrosine-repressible enzyme is also active in leucine biosynthesis. The ilvE gene product alone can reverse a phenylalanine requirement. Biochemical studies on extracts of strains carrying combinations of these aminotransferase mutations confirm the existence of two distinct enzymes with overlapping specificities for the alpha-keto acid analogues of tyrosine, phenylalanine, and aspartate. These enzymes can be distinguished by electrophoretic mobilities, by kinetic parameters using various substrates, and by a difference in tyrosine repressibility. In extracts of an ilvE- tyrB- aspC- triple mutant, no aminotransferase activity for the alpha-keto acids of tyrosine, phenylalanine, or aspartate could be detected.
Biochemical characterization of an Escherichia coli hisT strain
Authors: Lawther R P , Hatfield W
Published: January 2020

An Escherichia coli hisT strain was characterized biochemically and shown to contain altered transfer ribonucleic acid and to be altered in the regulation of amino acid biosynthesis.
Effect of temperature on the growth of Myxococcus xanthus
Authors: Janssen G R , Wireman J W , Dworkin M
Published: January 2020

The cardinal growth characteristics of Myxococcus xanthus were examined from 14 to 40 degree C, and the examinations indicated that the organism is mesophilic in character. The maximum growth rate (0,3 doublings per h) was between 34 and 36 degree C and the temperature characteristic (micron) is 17,000 cal/mol (71,162 J/mol).
Mutations in the L-arabinose operon of Escherichia coli B/r with reduced initiator function
Authors: Gonzalez I L , Sheppard D E
Published: January 2020

Partial reversion mutants derived from a strain containing a strongly polar initiator-defective mutation (araI1036) in the L-arabinose operon were found to have several characteristics expected of mutants with reduced initiator function. These reversion mutations are cotransduced with the ara region and are probably within the araI region. Furthermore, they permit induction of the L-arabinose operon to a level only one-third of the normal wild-type level. These partially functional initiator regions reduce the expression of structural genes in the cis position only; they function quite independently of wild-type or defective initiator regions in the trans position. These mutants exhibit a two- to threefold increase in the rate of expression of ara operon genes within one-tenth of a generation after a shift of the growth temperature from 28 to 42 degrees C. This suggests that the temperature optimum for initiation of operon expression is higher for the partial revertant strains than it is for strains containing a wild-type initiator region.
Analysis of Euglena gracilis chloroplast deoxyribonucleic acid with a restriction endonuclease, EcoRI
Authors: Mielenz J R , Milner J J , Hershberger C L
Published: January 2020

Cleavage of chloroplast deoxyribonucleic acid (DNA) of Euglena gracilis Z with restriction endonuclease RI from Escherichia coli (EcoRI) yielded 23 bands upon electrophoresis in gels of agarose. Four of the bands contained twice the stoichiometric amount of DNA. One of these bands contained two similarly sized fragments. The sum of the molecular weight of the 24 different fragments equaled the molecular weight of the circular molecule. The restriction fragments had different buoyant densities, with four having distinctly heavy densities in CsCl. Restriction fragments with a high buoyant density were preferentially lost when broken chloroplast DNA was purified by equilibrium density gradient centrifugation. Hybridization of chloroplast ribosomal ribonucleic acid to intact chloroplast DNA determined that there are two cistrons for 16S and 23S ribosomal ribonucleic acid. These two cistrons are located on six restriction fragments, all of which have buoyant densities greater than the intact molecule of chloroplast DNA.
Characterization of plasmids determining hemolysin and bacteriocin production in Streptococcus faecalis 5952
Authors: Oliver D R , Brown B L , Clewell D B
Published: January 2020

Two plasmids designated pOB1 and pOB2 were isolated from Streptococcus faecalis strain 5952 and found to have molecular weights of approximately 46 X 10(6) and 28 X 10(6), respectively. pOB1 was found to determine hemolytic activity and was transmissible, whereas pOB2 appeared to determine a bacteriocin that is specifically inhibitory to S. faecalis strains harboring the 26-megadalton plasmid pAM539.
Coordinate control of the synthesis of ribonucleoside diphosphate reductase components in Escherichia coli
Authors: Fuchs J A
Published: January 2020

Ribonucleoside diphosphate reductase subunits B1 and B2 and ether-permeabilized cell activities of Escherichia coli increase in parallel during thymine deprivation. Thioredoxin and thioredoxin reductase activities are not affected by thymine deprivation.