bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of arginine utilization in Neurospora
Authors: Weiss R L , Davis R H
Published: January 2020

The response of Neurospora to changes in the availibility of exogenous arginine was investigated. Upon addition of arginine to the growth medium, catabolism is initiated within minutes. This occurs prior to expansion of the arginine pool or augmentation of catabolic enzyme levels. (Basal levels are approximately 25% of those found during growth in arginine-supplemented medium.) Catabolism of arginine is independent of protein synthesis, indicating that the catabolic enzymes are active but that arginine is not available for catabolism unless present in the medium. Upon exhaustion of the supply of exogenous arginine, catabolism ceases abruptly, despite an expanded arginine pool and induced levels of the catabolic enzymes. The arginine pool supports protein synthesis until the cells regain their normal capacity for endogenous arginine synthesis. These observations, combined with the known small level of induction of arginine catabolic enzymes, non-repressibility of most biosynthetic enzymes, and vesicular localization of the bulk of the arginine pool, suggest that compartmentation plays a significant role in controlling arginine metabolism in Neurospora.
Control of morphogenesis in Arthrobacter crystallopoiets: effect of cyclic adenosine 3',5'-monophosphate
Authors: Hamilton R W , Achberger E C , Kolenbrander P E
Published: January 2020

The intracellular levels of cyclic adenosine 3',5'-monophosphate (cyclic AMP) were measured at various intervals during growth and morphogenesis in Arthrobacter crystallopoietes. Cyclic AMP levels remained relatively constant throughout growth in spherical cells grown in glucose-based media. Immediately after inoculation of spheres from glucose- to succinate-containing media, a 30-fold increase in intracellular cyclic AMP was detected. This dramatic rise in cyclic AMP preceded the observed change in cellular morphology from spheres to rods. The cyclic AMP level in rod-shaped cells rapidly dropped to a relatively stable concentration during the exponential growth phase. At the onset of stationary phase and rod-to-sphere morphological transition, a second peak of cyclic AMP was observed. Neither of these two peaks was detectable in a morphogenetic mutant that grew only as spheres. The intracellular levels of cyclic AMP in this mutant remained constant throughout exponential growth and decreased slightly during stationary phase. Effects of exogenously added cyclic nucleotides and their derivatives to both parent and mutant cultures were investigated. The data presented indicate that dramatic changes in intracellular cyclic AMP levels occur just before the morphological transitions characteristic of the morphogenetic cycle in A. crystallopoietes. It is suggested that cyclic AMP is a contributing factor in the regulatory phenomenon associated with morphogenesis in this bacterium.
Media dependence of commitment in Bacillus subtilis
Authors: Cooney P H , Whiteman P F , Freese E
Published: January 2020

At some time during sporulation development, cells of Bacillus subtilis develop a commitment to continue sporulation even after addition of or dilution into a fresh nutrient. The extent of commitment was measured by the titer of spores produced at the time at which the original culture sporulated maximally. Since newly formed spores of B. subtilis soon germinate in the replenished medium, the measurement of their titer, especially of heat-resistant spores, gave low values. This problem was avoided by the germination-delaying effect of methyl anthranilate (1 mM) when added together with the fresh nutrients. In a given culture, the titer of committed cells was then independent of the method by which it was measured, i.e., by the phase-bright, octanol-resistant, or heat-resistant spore titer. The time of commitment depended on the type of nutrient added. Commitment occurred earlor casein hydrolysate. The rates at which non-metabolizable amino acid analogues or the 14C from an amino acid mixture were taken up by the cells increased toward the end of growth and later declined. This decline occurred slowly and was only weakly correlated with the commitment time of an analogous amino acid.
Oscillations in the synthesis of cell wall components in synchronized cultures of Escherichia coli
Authors: Hakenbeck R , Messer W
Published: January 2020

The rate of cell wall synthesis with respect to both proteins and lipids was determined in synchronized cultures of Escherichia coli B/r. Whereas the rate of total protein synthesis showed an exponential increase with cell age, the rate of incorporation of proteins and lipids into cell wall had a maximum at a cell age of 30 to 35 min, 15 min before cell division. This oscillation was observed in both the cytoplasmic membrane and in the outer membrane of the cell envelope.
Composition and enzyme activities of Spiroplasma citri membranes
Authors: Mudd J B , Ittig M , Roy B , Latrille J , Bové J M
Published: January 2020

Spiroplasma citri was cultured in three different media that supplied cholesterol and fatty acids from: (i) horse serum, (ii) pleuropneumonia-like organism (PPLO) serum fraction, or (iii) bovine serum albumin-fatty acid-cholesterol. The ability of PPLO serum fraction to support growth varied by lot number. Neither PPLO serum fraction nor the bovine serum albumin medium supported growth as well as the horse serum medium. Analysis of cholesterol, lipid phosphorus, and membrane protein showed the horse serum- and PPLO-grown cells to be indistinguishable, but the bovine serum albumin-grown cells were deficient in lipid phosphorus. The three cultures did not show markedly different fatty acid compositions, but, in all cases, the cultures preferentially incorporated palmitic acid and discriminated against linoleic acid. Cultures grown for different times from logarithmic growth through a degenerative phase showed relatively constant ratios of cholesterol/protein and lipid phosphorus/protein. Fatty acid composition was also relatively constant at the different stages. Adenosine triphosphatase and p-nitrophenyl phosphatase were mainly associated with the membrane, whereas reduced nicotinamide adenine dinucleotide oxidase was either readily removed or not associated with the membrane. The reduced nicotinamide adenine dinucleotide oxidase was inactivated at temperatures above 35 degrees C.
Formation and function of Vibrio parahaemolyticus lateral flagella
Authors: Shinoda S , Okamoto K
Published: January 2020

Formation of the lateral flagella (L-flagella) of Vibrio parahaemolyticus was studied immunologically, using specific antiserum against L-flagella. On solid medium, L-flagella were formed at both high (37 degrees C) and low (25 degrees C) temperatures, although at high temperatures they became dissociated from the cells and decomposed in the medium. L-flagella were not formed in liquid or soft-agar medium. Formation of L-flagella was decreased by lowering the pH of the medium and repressed by transferring the cells from solid medium to liquid medium. Mutants possessing L-flagella but not a polar monotrichous flagellum (M-flagellum) swarmed on solid medium, whereas mutants were grown on solid medium and then transfered to liquid medium, the cells oscillated until they lost L-flagella. It is postulated that L-flagella are locomotive organelles on solid medium and in some cases also in liquid medium, whereas M-flagella are locomotive organelles only in liquid medium.
Inhibition of aminoacyl-transfer ribonucleic acid synthetases and the regulation of amino acid biosynthetic enzymes in Neurospora crassa
Authors: Spurgeon S L , Matchett W H
Published: January 2020

Growth conditions that result in the accumulation of the tryptophan intermediate indoleglycerol phosphate or of the histidine intermediate imidazoleglycerol phosphate cause mycelia of Neurospora crassa to exhibit an immediate and sustained increase in the differential rate at which the biosynthetic enzymes of the tryptophan, histidine, and arginine pathways are synthesized. These accumulated intermediates are shown to be inhibitors of the activity of aminoacyltransfer ribonucleic acid (tRNA) synthetases, as judged by an in vitro esterification assay. The tryptophan intermediate is shown to inhibit the charging of tryptophan, and the histidine intermediate is shown to inhibit charging of histidine. The inhibitions noted are consistent with the finding that the level of charged tRNATrp is decreased significantly in cells that have accumulated indoleglycerol phosphate and that of tRNAHis is decreased significantly in cells that have accumulated imidazoleglycerol phosphate. These results are interpreted as support for the involvement of aminoacyl-tRNA species in mediating cross-pathway regulation of the tryptophan, histidine, and arginine biosynthetic pathways as proposed in Lester's polyrepressor hypothesis (G. Lester, 1971). the correlations noted lead to the conclusion that Neurospora utilizes regulatory mechanisms that have the ability to react to changes in the level of charging of tRNA species.
Host cell and ultraviolet reactivation of ultraviolet-irradiated Mycoplasmaviruses
Authors: Das J , Nowak J A , Maniloff J
Published: January 2020

The mycoplasma Acholeplasma laidlawii was shown to have mechanisms for both host cell and ultraviolet (UV) reactivation of UV-irradiated mycoplasmaviruses. Host cell reactivation was examined by comparing the survival abilities of UV-irradiated double-stranded deoxyribonucleic acid mycoplasmavirus plated on both untreated and on acriflavine-treated cells. Acriflavine treatment inhibited cell exision repair. Decreased survival on the acriflavine-treated cells demonstrated host cell reactivation. UV reactivation was studied by comparing the survival of UV-irradiated virus plated on untreated cells with its survival on cells that received a small UV dose before plating. The UV-irradiated cells gave increased virus survival, showing UV reactivation. Similar experiments with a single-stranded deoxyribonucleic acid mycoplasmavirus showed that this virus could be UV reactivated, but not host cell reactivated.
Identification of a phosphorus-containing storage granule in the cyanobacterium plectonema boryanum by electron microscope x-ray microanalysis
Authors: Kessel M
Published: January 2020

Transmission electron microscopy of cyanobacteria couple with X-ray microanalysis has confirmed that dense deposits within these cells are composed of phosphorous.
Purification and some properties of an extracellular alpha-amylase from Bacteroides amylophilus
Authors: McWethy S J , Hartman P A
Published: January 2020

A medium was developed to obtain maximum yields of extracellular amylase from Bacteroides amylophilus 70. Crude enzyme preparation, obtained by ammonium sulfate precipitation of cell-free broth, contained six amylolytic isoenzymes that were detected by isoelectric focusing and polyacrylamide gel electrophoresis. One of these amylases was purified by diethylaminoethyl-Sephadex A-50 ion-exchange chromatography and Sephadex G-200 gel filtration techniques. Some properties of the purified extracellular alpha-amylase were: optimum pH, 6.3; optimum temperature, 43 degrees C: PH stability range, 5.8 to 7.5; isoelectric point, pH 4.6; molecular weight, 92,000 (by sodium dodecyl sulfatedisc gel electrophoresis); and sugars causing inhibition, cyclomaltoheptaose, cyclomaltohexaose, and alpha-d-phenylglucoside. In addition, Ca2+ and Co2+ were strong activators,and Hg2+ was a strong inhibitior; all other cations were slightly stimulatory. Dialysis against 0.01 M ethylenediaminetetraacetic acid caused a 58% loss of activity that was restored to 92% of the original by the addition of 0.04 M Ca2+. The enzyme affected a blue-value-reducing-value curve characteristic of alpha-type amylases. The relative rates of hydrolysis of amylose, soluble starch, amylopectin, and dextrin were 100, 97, 92, and 60%, respectively; Michaelis constants for these substrates were 18.2, 18.7, 18.2, and 16.7 mumol of d-glucosidic bond/liter, respectively. The enzyme degraded maize (corn) starch granules to some extent and had relatively little activity on potato starch granules.
Effects of lipid phase transition of the freeze-cleaved envelope of Escherichia coli
Authors: Bayer M E , Dolack M , Houser E
Published: January 2020

We studied the fine structure of the envelope of Escherichia coli auxotroph K1060 after the cells were grown in the presence of one of the following fatty acids; oleic, palmitelaidic, or elidic acid. The cells were freeze-fractured after exposure to temperatures above and below the lipid phase transition range. As judged by freeze-etching methods, we observed that below the transition range the fracture plane of the inner membrane showed the typical aggregation of intramembranous particles (IMP) and concomitant development of areas devoid of IMP. In these areas we found a regular arrangement of equally spaced ridges, often intersected at 90 degrees by arrays of similar ridges. The ridges were composed of spherical particles measuring 4 to 5 nm in diameter. Formation and melting of these arrays took place within 15 to 30s after temperature shift-down or shift-up, respectively. Fixation in glutaraldehyde prevented these changes. The outer-membrane fracture plane revealed ordered areas to a lesser degree; these were discernible only by the regular arrangement of the IMP of the concave fracture plane. We interpret the data by suggesting that the pattern of ridges in E. coli K1060 is analogous to the band patterns described for artificial liposomes, and that the particles, possibly proteins, are lined up or extruded along the ridges during membrane lipid crystallization.
Protoplast formation of selected Mycobacterium smegmatis mutants by lysozyme in combination with methionine
Authors: Yabu K , Takahashi S
Published: January 2020

Lysozyme-sensitive mutants of Mycobacterium smegmatis, isolated by nitrosoguanidine treatment, have been converted into protoplasts in a nutritionally enriched medium containing lysozyme and DL-methionine.
Physiological regulation of a decontrolled lac operon
Authors: Wanner B L , Kodaira R , Neidhart F C
Published: January 2020

The expression of the lac operon was studied under a variety of growth conditions in induced and in constitutive cells of Escherichia coli that carried different catabolite-insensitive lac promoters. Use of such "decontrolled" lac operons permitted a study of the expression of an operon that was presumably subject only to passive control. Since the use of toluenized cells was demonstrated not to be completely reliable, all enzyme assays were performed on sonic supernatant fluids. The cells contained different catabolite-insensitive promoters, which included the L1 and UV5 lac promoters, as well as others isolated in this study. There were three major observations. First, small but real carbon source effects were seen. Second, there was only a small change in beta-galactosidase specific activity with changes in the growth rate. This result implies a limited transcription and/or translation capacity within the cell. Third, at rapid growth rates, most promoters exhibited a decreased expression. The UV5 promoter, which was the "strongest" promoter, was an exception. A mechanism to explain this promoter-dependent control is discussed.
Cellular distribution of ornithine in Neurospora: anabolic and catabolic steady states
Authors: Bowman B J , Davis R H
Published: January 2020

During growth on minimal medium, cells of Neurospora contain three pools of ornithine. Over 95% of the ornithine is in a metabolically inactive pool in vesicles, about 1% is in the cytosol, and about 3% is in the mitochondria. By using a ureaseless strain, we measured the rapid flux of ornithine across the membrane boundaries of these pools. High levels of ornithine and the catabolic enzyme ornithine aminotransferase coexist during growth on minimal medium but, due to the compartmentation of the ornithine, only 11% was catabolized. Most of the ornithine was used for the synthesis of arginine. Upon the addition of arginine to the medium, ornithine was produced catabolically via the enzyme arginasn early enzyme of ornithine synthesis. The biosynthesis of arginine itself, from ornithine and carbamyl phosphate, was halted after about three generations of growth on arginine via the repression of carbamyl phosphate synthetase A. The catabolism of arginine produced ornithine at a greater rate than it had been produced biosynthetically, but this ornithine was not stored; rather it was catabolized in turn to yield intermediates of the proline pathway. Thus, compartmentation, feedback inhibition, and genetic repression all play a role to minimize the simultaneous operation of anabolic and catabolic pathways for ornithine and arginine.
Suppression of an Escherichia coli dnaA mutation by the integrated R factor R100.1: generation of small plasmids after integration
Authors: Chandler M , Silver L , Frey J , Caro L
Published: January 2020

We have observed that integration of the R plasmid R100.1 into the chromosome of Escherichia coli is associated with the formation of small, covalently closed circular elements. Contour length measurements, partial denaturation mapping, and analysis of the deoxyribonucleic acid fragments produced by digestion of one of these, pLC1, with the restriction endonuclease EcoRI indicate that it is the r-determinant element of R100.1.
Lecithin Requirement for the Sporulation Process in
Neurospora crassa
Authors: Juretic Davor
Published: January 2020

Reversible inhibition of conidiogenesis occurred when lecithin was depleted from
Neurospora
membranes by choline starvation.
Mutational analysis of serine-glycine biosynthesis in Rhodopseudomonas capsulata
Authors: Beremand P D , Sojka G A
Published: January 2020

Rhodopseudomonas capsulata possesses the enzymes of both the "phosphorylated" and the "non-phosphorylated" pathways of serine biosynthesis. Certain mutants with lesions in the phosphorylated pathway are serine-glycine auxotrophs, though they still produce enzymes of the non-phosphorylated sequence. These results indicate that the phosphorylated pathway is essential for the synthesis of serine and glycine in R. capsulata under the condtions tested.
Deoxyribonucleic acid repair in Escherichia coli mutants deficient in the 5'----3' exonuclease activity of deoxyribonucleic acid polymerase I and exonuclease VII
Authors: Chase J W , Masker W E
Published: January 2020

A series of Escherichia coli strains deficient in the 5'----3' exonuclease activity associated with deoxyribonucleic acid (DNA) polymerase I (exonuclease VI) and exonuclease VII has been constructed. Both of these enzymes are capable of pyrimidine dimer excision in vitro. These strains were examined for conditional lethality, sensitivity to ultraviolet (UV) and X-irradiation, postirradiation DNA degradation, and ability to excise pyrimidine dimers. It was found that strains deficient in both exonuclease VI (polAex-) and exonuclease VII (xseA-) are significantly reduced in their ability to survive incubation at elevated temperature (43 degrees C) beyond the reduction previously observed for the polAex single mutants. The UV and X-ray sensitivity of the exonuclease VI-deficient strains was not increased by the addition of the xseA7 mutation. Mutants deficient in both enzymes are about as efficient as wild-type strains at excising dimers produced by up to 40 J/m2 UV. At higher doses strains containing only polAex- mutations show reduced ability to excise dimers; however, the interpretation of dimer excision data at these doses is complicated by extreme postirradiation DNA degradation in these strains. The additional deficiency in the polAex xseA7 double-mutant strains has no significant effect on either postirradiation DNA degradation or the apparent deficiency in dimer excision at high UV doses observed in polAex single mutants.
Different binding sites for entry and exit of amino acids in whole cells of Mycobacterium phlei
Authors: Israeli E , Kalra V K , Brodie A F
Published: January 2020

On the basis of mutual inhibition of uptake with different amino acids in whole cells of Mycobacterium phlei, it was demonstrated that the binding site of proline was different from those of all other amino acids studied. Other groups of amino acids share a common binding site: lysine, histidine, and arginine; valine, leucine, and isoleucine; tryptophan, tyrosine, and phenylalanine; glutamic acid and aspartic acid. The exit and entry processes were studied for proline, glutamine, and glutamic acid. It was observed that in each case the entry and exit processes were mediated by different membrane sites.
Recovery of Saccharomyces cerevisiae mating-type a cells from G1 arrest by alpha factor
Authors: Chan R K
Published: January 2020

Mating-type a cells of the yeast Saccharomyces cerevisiae that had been specifically arrested in the G1 phase of the cell cycle by alpha factor, an oligopeptide pheromone made by alpha cells, recovered and resumed cell division after a period of inhibition which was dependent on the concentration of alpha factor used. These treated a cells were more resistant to alpha factor than untreated a cells, but lost their resistance upon further cell division. However, cells arrested for 6 h were no more resistant to alpha factor than cells arrested for only 2.5 h. Mating-type a strains could inactivate or remove alpha factor from the culture fluid, but two a sterile (nonmating) mutants and an a/alpha diploid strain could not. These results suggest that a cells have a mechanism, which may involve uptake or inactivation of alpha factor, for recovering from alpha factor arrest. However, the results do not distinguish between a recovery mechanism which is constitutive and one which is induced by alpha factor. The loss of alpha factor activity during recovery appeared to be primarily cell contact mediated, although an extracellular, diffusible inhibitor of alpha factor that is labile or that functions stoichiometrically could not be ruled out.
Synthesis of R-plasmid-coded beta-lactamase in minicells and in an in vitro system
Authors: Grindley J N , Blumberg R , Nakada D
Published: January 2020

beta-Lactamase encoded by a small, nontransferring R-plasmid, NTP1, conferring ampicillin resistance to its host bacteria, was purified. NTP1 plasmid-coded beta-lactamase was found to be periplasmically located in the host Escherichia coli cell, to have a molecular weight of about 25,000, and to show a relatively low activity against oxacillin and methicillin compared with benzylpenicillin. These characteristics indicate that NTP1 plasmid-coded beta-lactamase is very similar or identical to the "TEM-type" beta-lactamase, which is the most common beta-lactamase coded by R-plasmids in enteric bacteria. In minicells containing NTP1 plasmids, at least six plasmid-specific proteins were synthesized, and beta-lactamase was synthesized in a greater amount than other plasmid-coded proteins. In a cell-free transcription-translation coupled system from E. coli, NTP1 plasmid deoxyribonucleic acid directed the synthesis of several species of plasmid-specific proteins, including active beta-lactamase. The in vitro system also showed preferential synthesis of beta-lactamase, as was observed in minicells containing NTP1 plasmids.
Biosynthesis of wall polymers in Bacillus subtilis
Authors: Wyke A W , Ward J B
Published: January 2020

Preparations of membrane plus wall derived from Bacillus subtilis W23 were used to study the in vitro synthesis of peptidoglycan and teichoic acid and their linkage to the preexisting cell wall. The teichoic acid synthesis showed an ordered requirement for the incorporation of N-acetylglucosamine from uridine 5'-diphosphate (UDP)-N-acetylglucosamine followed by addition of glycerol phosphate from cytidine 5'-diphosphate (CDP)-glycerol and finally by addition of ribitol phosphate from CDP-ribitol. UDP-N-acetylglucosamine was not only required for the synthesis of the teichoic acid, but N-acetylglucosamine residues formed an integral part of the linkage unit attaching polyribitol phosphate to the cell wall. Synthesis of the teichoic acid was exquisitely sensitive to the antibiotic tunicamycin, and this was shown to be due to the inhibition of incorporation of N-acetylglucosamine units from UDP-N-acetylglucosamine.
Partial purification of glycerophosphate acyltransferase from Escherichia coli
Authors: Snider M D , Kennedy E P
Published: January 2020

Glycerophosphate acyltransferase, a membrane-bound enzyme catalyzing the initial step of phospholipid biosynthesis in Escherichia coli, has been extracted with Triton X-100, a nonionic detergent, and purified 20- to 40-fold. This preparation is free from lysophosphatidate acyltransferase. Glycerophosphate acyltransferase is inactive in detergent extracts, but can be reconstituted by the addition of phospholipid. Under such conditions, the enzyme is associated with phospholipid. The sole product of the reaction with acyl coenzyme A as substrate is 1-acyl-sn-glycero-3-phosphate. Furthermore, the enzyme shows a marked preference for saturated fatty acyl conenzyme A, implying that this enzyme is responsible for the predominance of saturated moieties in position 1 of E. coli phospholipids. Acyltransferase from two mutants, plsA and plsB, was partially purified and characterized. Results support the view that plsB is a structural gene for the acyltransferase, but suggest that the plsA gene product is not directly involved in phospholipid biosynthesis.
Rate of ribosomal ribonucleic acid chain elongation in Escherichia coli B/r during chloramphenicol treatment
Authors: Shen V , Bremer H
Published: January 2020

In Escherichia coli B/r growing in glucose-amino acids medium, the radioactive labeling of 5S ribosomal ribonucleic acid (rRNA) and transfer RNA (tRNA) was measured after the simultaneous addition to the bacteria of chloramphenicol (CAM) (100 mug/ml), rifampin (200 mug/ml), and radioactive uracil. Accumulation of 5S rRNA ceased 85 s after the addition of rifampin, independent of the presence or absence of CAM; this indicates that CAM did not affect the rRNA chain growth rate. Together with previous measurements of the synthesis of rRNA and messenger RNA under these conditions, the results imply that CAM caused a redistribution of RNA polymerase which greatly favored stable RNA synthesis (77 to 97% of total functioning RNA polymerase engaged in synthesis of rRNA and tRNA). Further, it is inferred that RNA polymerase molecules were activated that were inactive during exponential growth. The labeling of tRNA observed under these conditions suggests the existence of clusters of tRNA genes at the 3' end of long transcripts that resemble the rRNA precursor in length and response to CAM and may be parts of rRNA transcripts.
Basis for the Observed Fluctuation of Carboxypeptidase II Activity During the Cell Cycle in BUG 6, a Temperature-Sensitive Division Mutant of
Escherichia coli
Authors: Beck Barbara D. , Park James T.
Published: January 2020

Diaminopimelyl-
d
-alanyl carboxypeptidase (carboxypeptidase II) is most active at the time of division, whether measured in toluene-treated cells of
Escherichia coli
K-12 strain D11-1, fractionated by size, or in toluene-treated cells of the temperature-sensitive division mutant, BUG 6 (B. D. Beck and J. T. Park, 1976). The present investigation has now shown that, under conditions that permit division, the increased carboxypeptidase II activity in toluenetreated cells of BUG 6 is probably not due to protein synthesis. Although dividing cells are more permeable than nondividing cells, permeability differences are not sufficient to account for the changes in carboxypeptidase II activity. Thus, in the toluene-treated nondividing cells, carboxypeptidase II is present, but its activity is masked, which suggests the presence of an inhibitor. Another striking difference between nondividing and dividing cells is that carboxypeptidase II is much more readily released from dividing cells by both tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetic acid and toluene treatment. Carboxypeptidase II was partially purified and found to be an 86,000-molecular-weight protein consisting of two 43,000-molecular-weight polypeptides. Tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetic acid treatment of nondividing cells releases less than 10% of the carboxypeptidase II and other periplasmic proteins that are releasable from dividing cells.
Methanococcus vannielii: ultrastructure and sensitivity to detergents and antibiotics
Authors: Jones J B , Bowers B , Stadtman T C
Published: January 2020

Methanococcus vannielii is a strictly anaerobic motile coccus that possesses a tuft of flagellae. The cells are markedly sensitive to mechanical stress and are readily lysed by detergents, but the organism grows normally in media of low ionic strength. The absence of a typical cell wall, further suggested by resistance of M. vannielii to penicillin, cycloserine, and vancomycin, was confirmed by ultrastructural studies. Electron micrographs showed that the cell envelope lacks a peptidoglycan layer. On the outer surface there is a regular array of subunits similar to those of the glycoprotein envelopes of the halobacteria. However, the M. vannielii cell envelope, unlike those of the holobacteria, is unable to maintain a definite shape, and a high salt concentration is not required for its integrity.
Replicative Deoxyribonucleic Acid Synthesis in Isolated Mitochondria from
Saccharomyces cerevisiae
Authors: Mattick John S. , Hall Ruth M.
Published: January 2020

The characteristics of a system for the in vitro synthesis of mitochondrial deoxyribonucleic acid (mtDNA) in mitochondria isolated from
Saccharomyces cerevisiae
are described. In this system the exclusive product of the reaction is mtDNA. Under optimal conditions the initial rate of synthesis is close to the calculated in vivo rate; the rate is approximately linear for 20 min but then decreases gradually with time. DNA synthesis proceeds for at least 60 min and the de novo synthesis of an amount of mtDNA equivalent to 15% of the mtDNA initially present is achieved. The rate and extent of synthesis observed with mitochondria isolated from grande and petite (
rho
−
) strains were similar. The mode of DNA synthesis is semiconservative; after density labeling with 5-bromodeoxyuridine triphosphate, in vitro, the majority of labeled DNA fragments of duplex molecular weight, 6 × 10
6
, are of a density close to that calculated for hybrid yeast mtDNA. The density label is incorporated into one strand of the duplex molecules. These properties indicate that the synthesis resembles replicative rather than repair synthesis. This system therefore provides a convenient method for the study of mtDNA synthesis in
S. cerevisiae
. The observation that mtDNA synthesis is semiconservative in vitro suggests that the dispersive mode of synthesis observed in
S. cerevisiae
in vivo labeling studies is the result of some other process, possibly a high recombination rate.
Regulation of enzyme synthesis by the glutamine synthetase of Salmonella typhimurium: a factor in addition to glutamine synthetase is required for activation of enzyme formation
Authors: Bloom F R , Streicher S L , Tyler B
Published: January 2020

In Klebsiella aerogenes but not in Salmonella typhimurium glutamine synthetase can function during nitrogen-limited growth to increase the rate of synthesis of histidase from the hut genes of S. typhimurium 15-59 (hutS. 15-59). Formation of proline oxidase is also not increased in nitrogen-limited cultures of S. typhimurium. However, in hybrid strains of Escherichia coli or K. aerogenes, the glutamine synthetase of S. typhimurium activates synthesis of histidase from the hutS. 15-59 genes. Apparently, glutamine synthetase is necessary but not sufficient for activation of transcription of the hut genes; another factor must also be present. This factor is active in both K. aerogenes and E. coli but is missing or altered in S. typhimurium.
Dying of Gamma-Irradiated
Escherichia coli
Studied by the Use of Prophage
Authors: Petranović Drago , Zgaga Vera , Trgovčević Željko
Published: January 2020

Loss of the biological activity of deoxyribonucleic acid in gamma-irradiated
Escherichia coli
cells was studied. The study is based on two sets of experimental data: (i) post-irradiation heat inducibility of the cells whose chromosomes were “labeled” with the thermoinducible λ
c
I857
ind
prophage, and (ii) post-irradiation capacity of nonlysogenic cells to promote growth of the unirradiated λ
c
I857
ind
phage. The results show that, at the beginning of incubation after irradiation, the number of plaques formed upon heat induction of lysogenic cells was much higher than the viable cell count of the nonheated culture. This high resistance of the heat inducibility gradually decreased during post-irradiation incubation. Finally, after a period of 4 h, there was no difference in sensitivity between the heat inducibility and the colony-forming ability of gamma-irradiated cells. The capacity of gamma-irradiated bacteria to support growth of unirradiated λ
c
I857
ind
is radioresistant; this resistance, in contrast to that of heat inducibility, is much less affected during post-irradiation incubation. A continuous decrease in radioresistance of heat inducibility without a corresponding decrease in radioresistance of the capacity suggests that functional failure of initially undamaged and/or repaired parts of the chromosome gradually develops after irradiation. From the fact that after 4 h all colony formers are capable of being induced by heat, whereas no chromosomal activity can be detected in nonviable cells, two conclusions may be drawn: (i) gamma-irradiated
E. coli
cells destined to die reach their biological end point within 4 h of post-irradiation incubation; (ii) in most cells, functional failure of the whole chromosome is the immediate cause of death.
Control of Protein Synthesis in
Escherichia coli
: Analysis of an Energy Source Shift-Down
Authors: Johnsen Knud , Molin Søren , Karlström Olle , Maaløe Ole
Published: January 2020

The energy source shift-down described in the preceding paper (Molin et al., J. Bacteriol. 131: 7–17, 1977) was used to study the effects of shift-down on protein synthesis. The overall rate of protein synthesis was reduced immediately, and to the same extent, in stringent and relaxed strains. The primary effect of the shift was a slowing down of the polypeptide chain growth rate, a finding not previously reported. In stringent strains the normal, preshift rate was reestablished within 2 to 3 min, whereas in relaxed strains the chain growth rate remained low for about 20 min before slowly returning to the normal value, which was reestablished some 50 to 60 min after the shift. Throughout this transition, the stability of messenger ribonucleic acid (mRNA) remained unchanged in both strains. We interpret these findings as evidence of the more rapid reduction of the mRNA pool in the stringent strain after shift-down: we believe that very soon after the shift, the stringent strain reduces its pool of mRNA and with it the number of ribosomes engaged in protein synthesis. In this manner the number of active ribosomes is adjusted to the availability of energy and carbon. The relaxed strain cannot rapidly reduce its mRNA pool, which thus remains large enough to engage a near-preshift number of ribosomes during a prolonged period; as a consequence its ribosomes must work at a reduced rate. The possibility that ppGpp is involved in the control of mRNA production is discussed. After shift-down, the initial part of β-galactosidase (the auto-α fragment) was produced at a higher rate than complete β-galactosidase in the relaxed strain, as expected when translation is impeded.
Temperature-Sensitive Cell Division Mutants of
Escherichia coli
with Thermolabile Penicillin-Binding Proteins
Authors: Spratt Brian G.
Published: January 2020

The thermostability of the penicillin-binding proteins (PBPs) of 31 temperature-sensitive cell division mutants of
Escherichia coli
has been examined. Two independent cell division mutants have been found that have highly thermolabile PBP3. Binding of [
14
C]benzylpenicillin to PBP3 (measured in envelopes prepared from cells grown at the permissive temperature) was about 30% of the normal level at 30°C, and the ability to bind [
14
C]benzylpenicillin was rapidly lost on incubation at 42°C. The other PBPs were normal in both mutants. At 30°C both mutants were slightly longer than their parents and on shifting to 42°C they ceased dividing, but cell mass and deoxyribonucleic acid synthesis continued and long filaments were formed. At 42°C division slowly recommenced, but at 44°C this did not occur. The inhibition of division at 42°C was suppressed by 0.35 M sucrose, and in one of the mutants it was partially suppressed by 10 mM MgCl
2
. PBP3 was not stabilized in vitro at 42°C by these concentrations of sucrose or MgCl
2
. Revertants that grew as normal rods at 42°C regained both the normal level and the normal thermostability of PBP3. The results provide extremely strong evidence that the inactivation of PBP3 at 42°C in the mutants is the cause of the inhibition of cell division at this temperature and identify PBP3 as an essential component of the process of cell division in
E. coli
. It is the inactivation of this protein by penicillins and cephalosporins that results in the inhibition of division characteristic of low concentrations of many of these antibiotics.
Caulobacter crescentus pili: structure and stage-specific expression
Authors: Lagenaur C , Agabian N
Published: January 2020

Pili are functionally expressed during the predivisional and swarmer stages of the Caulobacter crescentus differentiation cycle. They appear on the developing swarmer pole and at the same cellular location as flagella and the phiCbK receptor sites. Pili disappear when the swarmer cell differentiates into a stalked cell; this occurs with the loss of flagella and the disappearance of phage receptor sites. C. crescentus CB13B1a pili have been purified and characterized. Monomeric pilin is a protein with an apparent molecular weight of 8,500 that stains weakly with periodic acid-Schiff reagent. The amino acid composition of purified pilin reveals very low quantities of basic amino acids and a complete absence of methionine. Pilin is synthesized throughout the C. crescentus differentiation cycle. Neither free pili nor pilin monomers are detectable in the growth media, suggesting that loss of piliation in the swarmer- to stalked-cell transition occurs via pilus retraction.
Further characterization of the F fertility inhibition systems of "unusual" Fin+ plasmids
Authors: Gasson M J , Willetts N S
Published: January 2020

Flac mutants insensitive to transfer inhibition by R factors. JR66a and R485 were isolated and characterized. Representative mutations were cis dominant and are therefore presumed to be at the sites of action, fisU and fisV, respectively, of the FinU and FinV transfer inhibition systems encoded by JR66a and R485. The mutants were used to confirm that the FinU and FinV fertility inhibition systems are different from each other and from the FinOP, FinQ, and FinW systems of R100, R62, and R455, respectively. Together with traO and fisQ mutants of Flac, the new mutants were also used to investigate the nature of the F fertility inhibition systems encoded by a further group of "unusual" Fin+ plasmids. Of these, two incompatibility group X plasmids were found to carry finO+ genes, and of five incompatibility group I plasmids, three encoded FinQ systems, one the FinU system, and one a new system (FinR). Transfer of a variety of derepressed F-like plasmids was inhibited by the FinQ, FinU, and FinV systems, but a quantitatively very different levels; this emphasizes the differences as well as the similarities between the conjugation systems of F-like plasmids.
Mutants of luminous bacteria with an altered control of luciferase synthesis
Authors: Waters C A , Hastings J W
Published: January 2020

Arginine is known to increase the luminescence in vivo and in vitro of the marine bacterium Beneckea harveyi growing in minimal medium. Mutants in which this arginine effect is either diminished, or absent were isolated as bright clones on a minimal medium after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. On a minimal medium both with and without added arginine and also on complex medium, these "minimal bright" mutants produce higher levels of luminescence than the wild type both in vivo and in vitro. This is attributed to the production of an increased amount of luciferase, which itself is wild type in terms of its specific activity.
Polyamines in trypanosomatids
Authors: Bacchi C J , Lipschik G Y , Nathan H C
Published: January 2020

Polyamines were determined by n-butanol extraction and thin-layer chromatography in four trypanosomatids: Trypanosoma brucei (rat infection) and cultures of Crithidia fasciculata, Leptomonas sp., and Trypanosoma mega. All had putrescine and spermidine but no detectable spermine. Putrescine and spermidine levels were quantitated for extracts of leptomonas during the normal growth cycle. Spermidine values peaked 18 h before peak cell populations. Spermidine-putrescine ratios for all organisms were related to the presumed phylogeny of the group.
Survey for alpha-(1 leads to 3)-glucanase activity among yeasts
Authors: Meyer M T , Phaff H J
Published: January 2020

Activity of alpha-(1 leads to 3)-glucanase was found in species of Cryptococcus, Rhodotorula, and Endomyces. Observations on the expression and stability of this enzyme in Rhodotorula minuta var. texensis was presented.
Induction of Colicin E1 Synthesis in Recombination-Defective Mutants in Both the RecBC and RecF Pathways
Authors: Nakazawa Atsushi , Suzuki Nobuo
Published: January 2020

Colicin E1 synthesis was induced in mutants defective in both the RecBC and RecF pathways to the same extent as in Rec
+
strains.
Variation in guanosine 5' ,3'-tetraphosphate levels in Chromatium
Authors: Klaussmann G , Miović M
Published: January 2020

Chromatium produces guanosine 5' ,3'-tetraphosphate, but there appears to be no correlation between guanosine 5' ,3'-tetraphosphate concentration and the inability of the organism to grow in certain light-dark regimes.
Genetic analysis of Escherichia coli K-12 region I flagellar mutants
Authors: Komeda Y , Silverman M , Simon M
Published: January 2020

Flagellar mutants in Escherichia coli region I were obtained by selection for resistance to the flagellotropic phage chi. F' elements carrying this region of the E. coli genome were then constructed. Stable merodiploid strains with a flagellar defect on the exogenate and another on the endogenote were prepared. These merodiploids yielded information on the complementation behavior of mutations in this region. Region I was shown to include at least six cistrons, flaV, flaK, flaL, flaM, flaS, and flaT. Mu-induced and deletion fla mutants were also isolated. By using these mutant strains, the transcriptional order was shown to be flaV-flaK-flaL-flaM-flaS-flaT. The definition of region I fla genes and their transcriptional relationships were confirmed by genetic tests with hybrid A phage carrying fla genes in this region.
Major proteins of the Escherichia coli outer cell envelope membrane as bacteriophage receptors
Authors: Datta D B , Arden B , Henning U
Published: January 2020

Three Escherichia coli phages, TuIa, TuIb, and TuII, were isolated from local sewage. We present evidence that they use the major outer membrane proteins Ia, Ib, and II, respectively, as receptors. In all cases the proteins, under the experimental conditions used, required lipopolysaccharide to exhibit their receptor activity. For proteins Ia and II, an approximately two- to eightfold molar excess of lipopolysaccharide (based on one diglucosamine unit) was necessary to reach maximal receptor activity. Lipopolysaccharide did not appear to possess phage-binding sites. It seemed that the lipopolysaccharide requirement reflected a protein-lipopolysaccharide interaction in vivo, and lipopolysaccharide may thus cause the specific localization of these proteins. Inactivation of phage TuII by a protein II-lipopolysaccharide complex was reversible as long as the complex was in solution. Precipitation of the complex with Mg2+ led to irreversible phage inactivation with an inactivation constant (37 degrees C)K = 7 X 10-2 ml/min per microgram. With phages TuIa and TuIb and their respective protein-lipopolysaccharide complexes, only irreversible inactivation was found at 37 degrees C. The activity of the three proteins as phage receptors shows that part of them must be located at the cells surface. In addition, the association of proteins Ia and Ib with the murein layer of the cell envelope makes this pair trans-membrane proteins.
Allantoin transport in Saccharomyces cerevisiae
Authors: Sumrada R , Cooper T G
Published: January 2020

Allantoin uptake in both growing and resting cultures of Saccharomyces cerevisiae occurs by a low-Km (ca. 15 micrometer) transport system that uses energy that is likely generated in the cytoplasm. This conclusion was based on the observation that transport did not occur in the absence of glucose or the presence of dinitrophenol, carbonyl cyanide-m-chloro-phenyl hydrazine, fluoride, or arsenate ions. Normal uptake was observed, however, in the presence of cyanide. The rate of accumulation was maximal at pH 5.2. In contrast to the urea transport system, allantoin uptake appeared to be unidirectional. Preloaded, radioactive allantoin was not lost from cells suspended in allantoin-free buffer and did not exchange with exogenously added, nonradioactive allantoin. Treatment of preloaded cells with nystatin, however, released the accumulated radioactivity. Allantoin accumulated within cells was isolated and shown to be chemically unaltered.
Effect of Carbon Source and the Role of Cyclic Adenosine 3′,5′-Monophosphate on the
Caulobacter
Cell Cycle
Authors: Kurn Nurith , Shapiro Lucille , Agabian Nina
Published: January 2020

The expression of cell cycle events in
Caulobacter crescentus
CB13 has been shown to be associated with regulation of carbohydrate utilization. Growth on lactose and galactose depends on induction of specific enzymes. Prior growth on glucose results in a delay in enzyme expression and cell cycle arrest at the nonmotile, predivisional stage. Dibutyryl cyclic adenosine 3′,5′-monophosphate (AMP) was shown to stimulate expression of the inducible enzymes and, thus, the initiation of the cell cycle. β-Galactosidase-constitutive mutants did not exhibit a cell cycle arrest upon transfer of cultures from glucose to lactose. Furthermore, carbon source starvation results in accumulation of the cells at the predivisional stage. The cell cycle arrest therefore results from nutritional deprivation and is analogous to the general control system exhibited by yeast (Hartwell, Bacteriol. Rev. 38:164-198, 1974; Wolfner et al., J. Mol. Biol.
96:
273-290, 1975), which coordinates cell cycle initiation with metabolic state. Transfer of
C. crescentus
CB13 from glucose to mannose did not result in a cell cycle arrest, and it was demonstrated that this carbon source is metabolized by constitutive enzymes. Growth on mannose, however, is stimulated by exogenous dibutyryl cyclic AMP without a concomitant increase in the specific activity of the mannose catabolic enzymes. The effect of cyclic AMP on growth on sugars metabolized by inducible enzymes, as well as on sugars metabolized by constitutive enzymes, may represent a regulatory system common to both types of sugar utilization, since they share features that differ from glucose utilization, namely, temperature-sensitive growth and low intracellular concentrations of cyclic guanosine 3′,5′-monophosphate.