bluuebunny/crossref_metadata_2025 huggingface dataset:
Rifampin disrupts conjugal and chromosomal deoxyribonucleic acid metabolism in Escherichia coli K-12 carrying some IncIalpha plasmids
Authors: Boulnois G J , Beddoes M J , Wilkins B M
Published: January 2020

The effects of rifampin and chloramphenicol on the transfer of ColIdrd-1 have been examined to determined whether transfer requires the synthesis of an untranslated species of ribonucleic acid (RNA), as proposed in models for the transfer of another IncIalpha plasmid, R64drd-11. When RNA synthesis was inhibited throughout mating by rifampin, ColI transfer between dna+ bacteria occurred at the normal rate for about 10 min and then stopped abruptly. Conjugational deoxyribonucleic acid (DNA) synthesis in dnaB mutants indicates that plasmid DNA was made in the rifampin-treated donors to replace the transferred material but the DNA tended to be unstable. In the presence of chloramphenicol, transfer of ColI gradually diminished over a longer period. Rifampin, but not chloramphenicol, was found to have unpredicted effects on chromosomal DNA metabolism in unmated dna+ and dnaB bacteria when they harbor any of three IncIalpha plasmids (ColIdrd-1, R144drd-3, and R64drd-11). Replication of the bacterial chromosome in such cells stopped abruptly about 15 min after the addition of rifampin, and at 41 degrees C, but not 37 degrees C, this was followed by extensive DNA breakdown. These findings suggest that curtailment of IncIalpha plasmid transfer by the drug results from a general disruption of DNA metabolism rather than from inhibition of a species of RNA essential for transfer.
Ionizing radiation damage to the folded chromosome of Escherichia coli K-12: sedimentation properties of irradiated nucleoids and chromosomal deoxyribonucleic acid
Authors: Ulmer K M , Gomez R F , Sinskey A J
Published: January 2020

The structures of the membrane-free nucleoid of Escherichia coli K-12 and of unfolded chromosomal deoxyribonucleic acid (DNA) were investigated by low-speed sedimentation on neutral sucrose gradients after irradiation with 60Co gamma rays. Irradiation both in vivo and in vitro was used as a molecular probe of the constraints on DNA packaging in the bacterial chromosome. The number of domains of supercoiling was estimated to be approximately 180 per genome equivalent of DNA, based on measurements of relaxation caused by single-strand break formation in folded chromosomes gamma irradiated in vivo and in vitro. Similar estimates based on the target size of ribonucleic acid molecules responsible for maintaining the compact packaging of the nucleoid predicted negligible unfolding due to the formation of ribonucleic acid single-strand breaks at doses of up to 10 krad; this was born out by experimental measurements. Unfolding of the nucleoid in vitro by limit digestion with ribonuclease or by heating at 70 degrees C resulted in DNA complexes with sedimentation coefficients of 1,030 +/- 59S and 625 +/- 15S, respectively. The difference in these rates was apparently due to more complete deproteinization and thus less mass in the heated material. These structures are believed to represent intact, replicating genomes in the form of complex-theta structures containing two to three genome equivalents of DNA. The rate of formation of double-strand breaks was determined from molecular weight measurements of thermally unfolded chromosomal DNA gamma irradiated in vitro. Break formation was linear with doses up to 10 krad and occurred at a rate of 0.27 double-strand break per krad per genome equivalent of DNA (1,080 eV/double-strand break). The influence of possible nonlinear DNA conformations on these values is discussed.
Characterization of a site-specific restriction endonuclease from Rhodopseudomonas sphaeroides
Authors: Lynn S P , Cohen L K , Gardner J F , Kaplan S
Published: January 2020

A type II restriction endonuclease, RshI, has been partially purified from photoheterotrophically grown Rhodopseudomonas sphaeroides strain 2.4.1. The enzyme preparation, after a single DE-52 column fractionation, is free of 5' exonuclease and phosphatase activities but contains a trace of 3' exonuclease activity. Based upon deoxyribonucleic acid (DNA) sequencing data in the vicinity of the enzyme-promoted cleavage of pBR322 DNA, we have concluded that RshI probably recognizes the palinodromic hexanucleotide sequence 5'-CGATCG-3' and cleaves between the T and C. lambda cI857 DNA contains three RshI sites, two of which lie in the replaceable region. The plasmid pBR322, which carries resistances to ampicillin and tetracycline, contains a single RshI site in the ampicillin resistance determinant. Insertion of DNA into the RshI site of pBR322 results in loss of ampicillin resistance but retention of tetracycline resistance, thereby providing a convenient screening procedure for recombinant plasmids.
Effect of ammonium ions on activity of hydrolytic enzymes during sporulation of yeast
Authors: Opheim D J
Published: January 2020

The addition of 10 mM ammonium sulfate to sporulation medium noncoordinately blocked the increases in protease C, protease B, alpha-mannosidase, and 1,4-amyloglucosidase activities which occur during normal sporulation of Saccharomyces cerevisiae, but had only a minor effect on the 10-fold increase in alkaline phosphatase activity.
A New Locus of
Escherichia coli
That Determines Sensitivity to Bacteriophage φX174
Authors: Munekiyo Reikichi , Tsuzuki Teruhisa , Sekiguchi Mutsuo
Published: January 2020

A new gene designated
phxB
, necessary for adsorption of φX174 to the cell surface of
Escherichia coli
, is located between
gal
and
aroG
on the
E. coli
chromosome.
Types of beta-lactamase determined by plasmids in gram-negative bacteria
Authors: Matthew M , Hedges R W , Smith J T
Published: January 2020

Two species of beta-lactamase determined by plasmids in enteric bacteria that show some resemblance to TEM enzymes are described. Both are distinct from all other plasmid-mediated beta-lactamases and differ from the TEM beta-lactamases in ability to hydrolyze some substrates, in isoelectric point, in immunological specificity, and in susceptibility to inhibition. One of the enzyme species, mediated by plasmid p453, has been briefly described previously. We have discovered that this beta-lactamase, designated SHV-1, is unique in its response to inhibition by the sulfhydryl group reagent p-chloromercuribenzoate, because the hydrolysis of cephaloridine but not that of benzylpenicillin is affected. This enzyme is found in a variety of plasmid types which were transferred from several bacterial species collected from a wide geographic range. The other enzyme species is novel; only a single plasmid determining this kind of beta-lactamase (designated HMS-1) has been detected.
Pyridine nucleotide cycle of Salmonella typhimurium: regulation of nicotinic acid phosphoribosyltransferase and nicotinamide deamidase
Authors: Foster J W , Kinney D M , Moat A G
Published: January 2020

Nicotinic acid phosphoribosyl transferase (NAPRTase) and nicotinamide deamidase activities from Salmonella typhimurium were examined regarding their regulation by either feedback inhibition or repression mechanisms. The results indicate that neither enzyme is subject to feedback inhbition. Nicotinamide deamidase does not appear to be under repression control. NAPRTase, however, is repressed when cells are grown in minimal medium supplemented with various intermediates of the pyridine nucleotide cycle. The concentration of exogenously supplied pyridine nucleotide necessary to effect repression of NAPRTas was found to be that concentration which will result in a nadA mutant generation time of less than 60 min. Furthermore, the results presented indicate that nicotinamide adenine dinucleotide is the actual corepressor molecule. The analogs 6-aminonicotinic acid and 6-aminonicotinamide were also capable of repressing NAPRTase, but only when an intact pyridine nucleotide cycl permitted conversion to 6-aminonicotinamide adenine dinucleotide. The role of a repressible NAPRTase is discussed in relation to the overall functioning of the pyridine nucleotide cycle.
Mechanisms controlling the two phosphate uptake systems in Neurospora crassa
Authors: Burns D J , Beever R E
Published: January 2020

The development of the high-affinity and low-affinity phosphate uptake systems of Neurospora crassa has been followed during germination and early growth. The ratio between the activities of the two systems became constant by the time exponential growth began, although the value of this ratio depended on the external phosphate concentration. The regulatory mechanisms controlling the systems were investigated by following the changes that resulted when exponentially growing germlings adapted to one phosphate concentration were shifted to a different concentration. The high-affinity system was derepressed under conditions of phosphate starvation, and inhibited irreversibly by feedback inhibition under conditions of over-supply. The low-affinity system was also derepressed and subject to feedback inhibition under comparable conditions, but, in contrast, inhibition of this system was reversible. A detailed description is given of the interplay between the systems during adaptation to changes in phosphate supply. Changes that occurred in the internal phosphate pool support the hypothesis that this metabolite is responsible for controlling the activities of the systems, either by triggering derepression of new uptake system synthesis or by inhibiting the existing system by feedback.
Demonstration of an internal fraction plane in cell walls of Streptococcus faecalis and Streptococcus mutans
Authors: Sleytr U B , Shockman G D , Higgins M L
Published: January 2020

The proposed lower internal density of the gram-positive wall was confirmed by observed an internal fracture plane in the walls of Streptococcus faecalis and Streptococcus mutans. However, the granular surfaces produced by this cleavage appeared to be more of a reflection of distortion during preparation than of subunit construction.
Altered membrane proteins in a minicell-producing mutant of Bacillus subtilis
Authors: Buchanan C E
Published: January 2020

The Bacillus subtilis minicell-producing mutant divIV-B1 has a membrane protein profile that is strikingly different from that of the other minicell-producing mutant, divIV-A1, or that of wild-type strain CU403.
Accelerated Adsorption of Bacteriophage T5 to
Escherichia coli
F, Resulting from Reversible Tail Fiber-Lipopolysaccharide Binding
Authors: Heller Knut , Braun Volkmar
Published: January 2020

A dual specificity for phage T5 adsorption to
Escherichia coli
cells is shown. The tail fiber-containing phages T5
+
and mutant hd-3 adsorbed rapidly to
E. coli
F (1.2 × 10
−9
ml min
−1
), whereas the adsorption rate of the tail fiber-less mutants hd-1, hd-2, and hd-4 was low (7 × 10
−11
ml min
−1
). The differences in adsorption rates were due to the particular lipopolysaccharide structure of
E. coli
F. Phage T4-resistant mutants of
E. coli
F with an altered lipopolysaccharide structure exhibited similar low adsorption for all phage strains with and without tail fibers. The same held true for
E. coli
K-12 and B which also differ from
E. coli
F in their lipopolysaccharide structures. Only the tail fiber-containing phages reversibly bound to isolated lipopolysaccharides of
E. coli
F. Infection by all phage strains strictly depended on the
tonA
-coded protein in the outer membrane of
E. coli
. We assume that the reversible preadsorption by the tail fibers to lipopolysaccharide accelerates infection which occurs via the highly specific irreversible binding of the phage tail to the
tonA
-coded protein receptor. The difference between rapid and slow adsorption was also revealed by the competition between ferrichrome and T5 for binding to their common
tonA
-coded receptor in
tonB
strains of
E. coli
. Whereas binding of T5
+
to
E. coli
K-12 and of the tail-fiber-less mutant hd-2 to
E. coli
F and K-12 was inhibited 50% by about 0.01 μM ferrichrome, adsorption of T5 to
E. coli
F was inhibited only 40% by even 1,000-fold higher ferrichrome concentrations.
Orientation of the guanine operon of Escherichia coli K-12 by utilizing strains containing guaB-xse and guaB-upp deletions
Authors: Vales L D , Chase J W , Murphy J B
Published: January 2020

Temperature induction of an Escherichia coli strains with lambda cI1857 integrated in the guaB gene has been used to produce strains containing chromosomal deletions extending into the xse and upp genes. By utilizing strains containing these deletions, it has been possible to order the genes in the guanine operon with respect to the xseA and upp genes. The order of the genes in this region is glyA-hisS-xseA-guaO-guaB-guaA-purG-upp-purC.
Pseudomonas cepacia mutants blocked in the direct oxidative pathway of glucose degradation
Authors: Lessie T G , Berka T , Zamanigian S
Published: January 2020

Glucose dehydrogenase-deficient strains of Pseudomonas cepacia grew normally with glucose as carbon source, indicating that the direct pathway of glucose oxidation does not play an essential role in this bacterium.
Fermentation of 1,2-Propanediol and 1,2-Ethanediol by Some Genera of
Enterobacteriaceae
, Involving Coenzyme B
12
-Dependent Diol Dehydratase
Authors: Toraya Tetsuo , Honda Susumu , Fukui Saburo
Published: January 2020

Klebsiella pneumoniae
(
Aerobacter aerogenes
) ATCC 8724 was able to grow anaerobically on 1,2-propanediol and 1,2-ethanediol as carbon and energy sources. Whole cells of the bacterium grown anaerobically on 1,2-propanediol or on glycerol catalyzed conversion of 1,2-diols and aldehydes to the corresponding acids and alcohols. Glucose-grown cells also converted aldehydes, but not 1,2-diols, to acids and alcohols. The presence of activities of coenzyme B
12
-dependent diol dehydratase, alcohol dehydrogenase, coenzyme-A-dependent aldehyde dehydrogenase, phosphotransacetylase, and acetate kinase was demonstrated with crude extracts of 1,2-propanediol-grown cells. The dependence of the levels of these enzymes on growth substrates, together with cofactor requirements in in vitro conversion of these substrates, indicates that 1,2-diols are fermented to the corresponding acids and alcohols via aldehydes, acyl-coenzyme A, and acyl phosphates. This metabolic pathway for 1,2-diol fermentation was also suggested in some other genera of
Enterobacteriaceae
which were able to grow anaerobically on 1,2-propanediol. When the bacteria were cultivated in a 1,2-propanediol medium not supplemented with cobalt ion, the coenzyme B
12
-dependent conversion of 1,2-diols to aldehydes was the rate-limiting step in this fermentation. This was because the intracellular concentration of coenzyme B
12
was very low in the cells grown in cobalt-deficient medium, since the apoprotein of diol dehydratase was markedly induced in the cells grown in the 1,2-propanediol medium. Better cell yields were obtained when the bacteria were grown anaerobically on 1,2-propanediol. Evidence is presented that aerobically grown cells have a different metabolic pathway for utilizing 1,2-propanediol.
Expression of the cloned uvrB gene of Escherichia coli: dependency on nonsense suppressors
Authors: Pannekoek H , Noordermeer I , van de Putte P
Published: January 2020

Recombinant plasmid pNP5, consisting of plasmid pMB9 on which the uvrB gene is cloned, fully complements for the defects due to chromosomal uvrB mutations in the presence of the amber suppressor sup-6 or supF. Correndonuclease II activity was also completely restored in in UvrB strains containing both plasmid pNP5 and amber suppressor sup-6, as compared with the parental UvrB+ strain. It is shown that the amber mutation which interferes with the expression of the cloned uvrB gene is located outside this gene. Apparently, the amber mutation exerts a polar effect on uvrB expression that is relieved by sup-6 or supF. Introduction of a rho mutation into suppressor-free UvrB strains, harboring pNP5, did not relieve the polarity caused by the amber mutation.
Neisseria gonorrhoeae membrane microenvironment studied by spin-label electron spin resonance: comparison of colony types
Authors: Newhall W J , Kleinhans F W , Rosenthal R S , Sawyer W D , Haak R A
Published: January 2020

Spin-label electron spin resonance was used to characterize the microenvironment around spin probes which localize (i) in membranes, (ii) at the membrane surface, or (iii) in the cytoplasm of living Neisseria gonorrhoeae. Four colony types (T1, T2, T3, and T4) of gonococci were compared on the basis of the electron spin resonance parameters 2T parallel to, S (order parameter), and tau c (microviscosity). The concentration of spin label used had little or no effect on viability. T1 and T2 gonococci were found to have a more restricted environment for molecular motion of a membrane surface spin label than did T3 and T4. The membrane fluidity, as measured by a membrane lipid spin label, of T4 (S = 0.571) was significantly greater than that of T1 or T3 (S = 0.580). This difference was detected at 37 degrees C, at 25 degrees C, in agar-grown bacteria, and in exponential-phase cells. Studies using spin labels which probe different levels of the membrane indicated the presence of a membrane flexibility gradient. Cytoplasmic spin-label studies indicated that the cytoplasm of all gonococcal colony types was three to five times more viscous than water.
Specialized lambda transducing bacteriophage which carries hisS, the structural gene for histidyl-transfer ribonucleic acid synthetase
Authors: Fishman S E , Kerchief K R , Parker J
Published: January 2020

A number of specialized lambda transducing bacteriophages which carry the Escherichia coli gene guaB were isolated from E. coli. One of these bacteriophages, lambda cI857 Sam7 d guaB-2, also carries hisS, the structural gene for histidyl-transfer ribonucleic acid synthetase (EC 6.1.1.21). Histidyl-transfer ribonucleic acid synthetase activities in induced and uninduced lysogens carrying lambda d guaB-2 indicate that the phage carries the entire structural gene and that the gene is under the control of an E. coli promoter. These conclusions were confirmed by the in vivo production of a protein encoded by the phage which comigrates with authentic histidyl-transfer ribonucleic acid synthetase on two-dimensional polyacrylamide gels.
Adherence of bacteria to mammalian cells: inhibition by tunicamycin and streptovirudin
Authors: Pan Y T , Schmitt J W , Sanford B A , Elbein A D
Published: January 2020

Group B streptococci were labeled either by growing the cells in [14C]fructose or by using the surface label 4,4'-[3H]diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid, which reacts with amino groups. A quantitative assay was developed by using these labeled bacteria to study the adherence of streptococci to canine kidney epithelial cells. The bacteria adhered to kidney cells that had been infected with influenza A virus, but did not adhere to uninfected cells. The binding of 3H-labeled group B streptococci was proportional to the number of bacteria added and showed saturation kinetics. The binding was blocked by the addition of unlabeled group B streptococci but was not affected by addition of streptococci from other groups. It was also blocked by mixing the 3H-labeled streptococci with influenza A virus before adding the bacteria to the kidney cells. When the kidney cells were infected with influenza virus in the presence of either tunicamycin or streptovirudin, these antibiotics inhibited the appearance of viral hemagglutinin in the kidney cells and also prevented the release of mature virus. In these experiments, the adherence of 3h-labeled streptococci was also inhibited. Tunicamycin was shown to block the incorporation of [14C]mannose into lipid-linked oligosaccharides and glycoprotein in both normal and virus-infected kidney cells. These data give strong support to the notion that adherence of streptococci to mammalian cells involves recognition of viral hemagglutinin, a glycoprotein whose synthesis is blocked by certain antibiotics.
Immunochemical characterization of glutamine synthetase from Neurospora crassa glutamine auxotrophs
Authors: Sánchez F , Dávila G , Mora J , Palacios R
Published: January 2020

Glutamine synthetase derived from two Neurospora crassa glutamine auxotrophs was characterized. Previous genetic studies indicated that the mutations responsible for the glutamine auxotrophy are allelic and map in chromosome V. When measured in crude extracts, both mutant strains had lower glutamine synthetase specific activity than that found in the wild-type strain. The enzyme from both auxotrophs and the wild-type strain was partially purified from cultures grown on glutamine as the sole nitrogen source, and immunochemical studies were performed in crude extracts and purified fractions. Quantitative rocket immunoelectrophoresis indicated that the activity per enzyme molecule is lower in the mutants than in the wild-type strain; immunoelectrophoresis and immunochemical titration of enzyme activity demonstrated structural differences between the enzymes from both auxotrophs. On the other hand, the monomer of glutamine synthetase of both mutants was found to be of a molecular weight similar to that of the wild-type strain. These data indicate that the mutations are located in the structural gene of N. crassa glutamine synthetase.
Suppression of a deletion mutation in the glutamine amidotransferase region of the Salmonella typhimurium trpD gene by mutations in pheA and tyrA
Authors: Tanemura S , Bauerle R
Published: January 2020

Prototrophic revertants of a trpD deletion mutant that lacks the glutamine amidotransferase domain of the bifunctional component II subunit of the anthranilate synthetase-phosphoribosyltransferase complex have been found to arise by the occurrence of sublethal missense mutations in either the pheA or tyrA loci. Such suppressor mutations were obtained directly by mutation of the wild-type pheA gene as well as indirectly by partial reversion of a variety of nonleaky pheA and tyrA mutations. The suppressor strains have only a portion of the normal level of the pheA or tyrA enzyme activity and thus experience a partial limitation in the synthesis of phenylalanine or tyrosine. This limitation leads to a relaxation of end-product regulation of the phenylalanine- or tyrosine-specific enzymes of the common aromatic pathway and to the overproduction of the branch point intermediate, chorismic acid, which is one of the substrates of the anthranilate synthetase reaction. It is proposed that the high intracellular level of chorismic acid acts to elevate the non-physiological NH3-dependent anthranilate synthetase activity of the component I subunit, thereby eliminating the need for the glutamine amidotransferase activity of the component II subunit. Consistent with this is the finding that phenylalanine and tyrosine are specific inhibitors of growth of the pheA and tyrA suppressor strains, respectively, causing a shutdown of the overproduction of chorismic acid by reestablishing normal end-product control of the common pathway.
Ultrastructure of the outer membrane of Salmonella typhimurium bacteriocin-resistant mutants deficient in the 33K protein
Authors: Lounatmaa K
Published: January 2020

Outer membrane mutants of Salmonella typhimurium deficient in one, two, or three of the 33,000-dalton (33K), 34K, and 36K outer membrane proteins (7) were studied by using thin sectioning and freeze-fracturing electron microscopy techniques. The outer concave fracture face of all mutants deficient in the 33K protein had numerous particleless patches. In contrast to all previously examined 34K to 36K-deficient mutants, the 33K-deficient mutants showed marked heterogeneity in the size and distribution of such "empty" patches between cells of a culture. One mutant was deficient in both the 33K and the 34K to 36K "porin" protein complex; its outer membrane had very large particleless smooth areas. It is concluded that the 33K protein on one hand and the porin on the other are both able to form intramembraneous particles.
Gene lon and plasmid inheritance in Escherichia coli K-12
Authors: Falkinham J O
Published: January 2020

Lon- mutants of Escherichia coli K-12 are deficient in the inheritance of F-plasmids by conjugation. This deficiency is distinct from the conjugation deficiency caused by overproduction of capsular polysaccharide which decreases donor-recipient pair formation.
Incompatibility group P-1 bla+ plasmids do not increase penicillin resistance of Pseudomonas acidovorans
Authors: Bruce D L , Warren R A
Published: January 2020

Incompatibility group P-1 plasmids with the bla+ genotype were transferred from various Escherichia coli strains to Pseudomonas acidovorans strain 29. When resistance to ampicillin was used as the criterion, none of these plasmids appeared able to express their Bla+ phenotype in this host. When the plasmids were subsequently transferred back from these ampicillin-sensitive P. acdiovorans transcipients to E. coli strains, it was found that the Bla+ phenotype was again expressed. Although beta-lactamase was not detected in cultures of P. acidovorans transcipients, macroiodometric determinations of beta-lactamase activity made on broken cell suspensions revealed that beta-lactamase was indeed synthesized. It was concluded that P. acidovorans strain 29 allows expression of the bla gene within the cell but that this organism is unable to excrete the enzyme.
Effect of protein synthesis on plasmid maintenance in Streptococcus faecalis
Authors: Murphey-Corb M , Murray M L
Published: January 2020

Plasmid-to-chromosome ratios in Enterobacteriaceae, upon interruption of protein synthesis by chloramphenicol, are either conserved or increased when measured by dye buoyant density centrifugation. We have found, on the other hand, that the effect of inhibition of protein synthesis on the amount of covalently closed circular deoxyribonucleic acid visualized by this method in two strains of Streptococcus faecalis appears to differ from these established systems. A three- to sixfold decrease in covalently closed circular deoxyribonucleic acid was observed when lysates of chloramphenicol-treated cultures were submitted to dye buoyant density centrifugation. A loss of covalently closed circular deoxyribonucleic acid was also evident from electrophoretic profiles of these lysates. Several conditions which could account for the apparent loss of covalently closed circular deoxyribonucleic acid upon inhibition of protein synthesis are discussed.
Ribosomal ribonucleic acid isolated from Salmonella typhimurium: absence of the intact 23S species
Authors: Winkler M E
Published: January 2020

Ribonucleic acid (RNA) isolated by four distinct methods and from a variety of Salmonella typhimurium strains lacked intact 23S ribosomal RNA (rRNA). On sucrose gradients which minimize aggregation, the vast majority of S. typhimurium rRNA sedimented as a 16S peak with a 14S shoulder. RNA from this region of the gradient was resolved into three discrete bands by electrophoresis in formamide. Two very minor S. typhimurium RNA peaks were resolved at 21S and 10S on sucrose gradients, and each peak formed discrete bands in electrophoresis. It is concluded that if S. typhimurium does possess an intact 23S rRNA species, this species is extremely "labile." The absence of isolatable S. typhimurium 23S rRNA possibly reflected in vivo processing of the rRNA before isolation. Under certain conditions, S. typhimurium rRNA formed discrete aggregates which sedimented similarly to intact Escherichia coli 23S rRNA.
Specificity in formation of type II F' plasmids
Authors: Hadley R G , Deonier R C
Published: January 2020

Eight new F' plasmids derived from Hfr strains in which F is integrated at the chromosomal element alpha 3 beta 3 have been isolated and subjected to restriction enzyme, hybridization, and electron microscope heteroduplex analysis. Plasmids carrying extensive amounts of bacterial deoxyribonucleic acid were produced even though they were obtained by selection for transfer of lac, which is closely linked to F in the parental Hfr strains. Seven plasmids were type II Flac+ proC+ purE+ plasmids, and one was a type I Flac+ proC+ plasmid. Five of the Flac+ proC+ purE+ plasmids contain approximately 284 kilobases of bacterial deoxyribonucleic acid, which is identical for all five within the resolution of the restriction enzyme analysis. Theses results indicate that type II F' plasmids are the predominant tra+ F' type from this region of the Escherichia coli K-12 chromosome and that the recombination events leading to formation of these plasmids exhibit site specificity.
Products of endogenous N-acetylglucosaminyltransferase activity of Dictyostelium discoideum during growth and early development
Authors: Crean E V , Lagerstedt J P , Rossomando E F
Published: January 2020

In the presence of Mn2+ and uridine diphosphate-N-acetyl-D-[14C]glucosamine, a total particulate fraction prepared from Dictyostelium discoideum amoebae catalyzed the transfer of N-acetyl[14C]glucosamine to endogenous membrane protein acceptors. No transfer to lipid acceptors was evident. The 14C products obtained from growth-phase and aggregation-competent amoebae were converted to glycopeptides by pronase digestion. The respective glycopeptides appeared identical in their chemical and chromatographic properties, suggesting that the same activity was functioning in both growing and differentiating cells. The results provided no evidence for developmental regulation of this activity in D. discoideum.
Membrane H+ conductance of Streptococcus lactis
Authors: Maloney P C
Published: January 2020

Membrane conductance to H+ was measured in the anaerobic bacterium Streptoccus lactis by a pulse technique employing a low driving force (0.1 pH unit; 6 mV). Over the pH range of 3.7 to 8.5, a constant value for passive H+ conductance was observed, corresponding to 0.2 mumol of H+/s per p/ unit per g, dry weight (1.6 microS/cm2 of surface area). The pH insensitivity of this low basal H+ conductance supports the idea that a circulation of protons can mediate highly efficiency engery transductions across the membranes of bacteria.
Distribution of coenzyme F420 and properties of its hydrolytic fragments
Authors: Eirich L D , Vogels G D , Wolfe R S
Published: January 2020

The ability of hydrolytic products of coenzyme F420 to substitute for F420 in the hydrogenase and nicotinamide adenine dinucleotide phosphate-liniked hydrogenase systems of Methanobacterium strain M.o.H. was kinetically determined. The nicotinamide adenine dinucleotide phosphate-linked hydrogenase system was employed to quantitate the levels of F420 in a number of methanogenic bacteria as well as in some nonmethanogens. Methanobacterium ruminantium and Methanosarcina barkeri contained low levels of F420, whereas other methanogens tested contained high levels (100 to 400 mg/kg of cells). F420 from six of the seven methanogens was tested by thin-layer electrophoresis and was found to be electrophoretically identical to that purified from Methanobacterium strain M.o.H. The only exception was M. barkeri, which contained a more electronegative derivative of F420. Acetobacterium woodii, Escherichia coli, and yeast extract contained no compounds able to substitute for F420 in the nicotinamide adenine dinucleotide phosphate-linked hydrogenase system.
Partial purification and characterization of thiosulfate oxidase from Pseudomonas aeruginosa
Authors: Schook L B , Berk R S
Published: January 2020

Soluble thiosulfate oxidase from Pseudomonas aeruginosa was purified 85-fold and coverted thiosulfate to tetrathionate by using either ferricyanide or cytochrome c as an electron acceptor.
Suppression of tif-mediated induction of SOS functions in Escherichia coli by an altered dnaB protein
Authors: D'Ari R , George J , Huisman O
Published: January 2020

The tif-1 mutation in the Escherichia coli recA gene is known to cause induction of the various "SOS" functions at high temperature, including massive synthesis of the recA protein, lethal filamentation, elevated mutagenesis, and, in lambda lysogens, induction of prophage. It is shown here that the deoxyribonucleic acid initiation mutation dnaB252 suppresses all these manifestations of tif expression. Induction of lambda by ultraviolet irradiation, however, is not affected by the dnaB252 mutation. No similar suppression of tif is observed with other dnaB mutations affecting deoxyribonucleic acid elongation or with other deoxyribonucleic acid initiation mutations at the dnaA and dnaC loci. The fact that an alteration of the dnaB protein specifically suppresses tif-mediated SOS induction implies a role of the replication apparatus in this process, as has been suggested for ultraviolet induction. The induction of lambda is known to proceed via repressor cleavage, presumably promoted by an activated (protease) form of the recA protein. Since lambda induction is normal after ultraviolet irradiation of the tif-1 dnaB252(lambda) strain, tif-mediated induction in this strain may be blocked in a tif-specific step leading to activation of the recA (tif) protein. It is possible that the recA (tif) mutant protein may be directly involved in the replication complex in processes leading to this activation.
Plasmid vehicles for direct cloning of Escherichia coli promoters
Authors: An G , Friesen J D
Published: January 2020

A multicopy plasmid cloning vehicle, pGA22, which carries genes for ampicillin resistance (Apr), tetracycline resistance (Tcr), chloramphenicol resistance (Cmr), and kanamycin resistance (Kmr) has been constructed. This plasmid has five unique sites for restriction endonucleases EcoRI, PstI, XhoI, SmaI, and SalI within antibiotic resistance genes. pGA22, which is 5.1 megadaltons in size, has a low copy number (probably fewer than 10 per genome), is capable of relaxed replication, and is mobilized by F-factor at a frequency of 10(-5). A series of promoter-cloning vehicles, pGA24, pGA39, and pGA46, has been developed from pGA22. In these plasmids the natural promoter for Tcr has been removed and has been replaced by small deoxyribonucleic acid fragments carrying unique sites for several restriction endonucleases. Cells carrying these vectors are sensitive to tetracycline unless insertional activation of the Tcr occurs by cloning a promoter-carrying deoxyribonucleic acid fragment in one of the unique sites adjacent to the 5' end of Tcr. In this way, promoters carried on a HindIII-generated deoxyribonucleic acid fragment can be inserted at the HindIII site of plasmid pGA24, pGA39, or pGA46. A promoter in fragments generated by digestion with restriction endonuclease XmaI or PstI or by any restriction endonucleases which generate flush ends, such as SmaI, PvuII, HpaI, HincII, or HaeIII, can be clones in plasmid pGA39. Plasmid pGA46 can be used to detect a promoter fragment carried on a BglII, BamHI, MboI, or PstI fragment. We also describe a plasmid, pGA44, with a unique KpnI site in the rifampin resistance gene rpoB.
Partition of alkane by an extracellular vesicle derived from hexadecane-grown Acinetobacter
Authors: Käppeli O , Finnerty W R
Published: January 2020

The enhanced solubility of hexadecane in the growth medium of hexadecane-grown Acinetobacter species has been related to the accumulation of an extracellular vesicular component. The partition of hexadecane was determined by measuring the amount of [3H]hexadecane bound to the vesicular particle. The vesicle was characterized as a phospholipid-rich, lipopolysaccharide-rich particle with a polypeptide composition similar to the outer membrane of Acinetobacter. The accumulation of an extracellular vesicular component that binds hexadecane in the form of a microemulsion represents another example of molecules produced by microorganisms in response to paraffinic substrates.
Selection for Escherichia coli mutants with proteins missing from the ribosome
Authors: Dabbs E R
Published: January 2020

Antibiotic-independent revertants of an erythromycin-dependent strain of Escherichia coli were isolated by spontaneous selection. Their ribosomal proteins were analyzed by two-dimensional polyacrylamide gel electrophoresis. In contrast to most ribosomally targeted selections, the specific absence of a certain protein from the ribosome, rather than alterations in ribosomal proteins, was observed. Mutants were found with protein S20, L11, L15, L28, L29, or L30 missing.
Purification and chemical characterization of the rodlet layer of Neurospora crassa conidia
Authors: Beever R E , Redgwell R J , Dempsey G P
Published: January 2020

The rodlet layer of Neurospora crassa macroconidia has been purified and chemically characterized. Sheets of rodlets were released from the conidial surface by vigorously shaking conidia in water. Conidia were removed by filtration and low-speed centrifugation, and the rodlets were recovered from the supernatant by high-speed centrifugation. The rodlet pellet comprised 1.9% of the initial dry weight. Chemical analysis was hampered by the insolubility of the rodlets. They were not solubilized by heating in various protein-denaturing buffers and were only partially dissolved by heating in 1 M NaOH at 100 degrees C for 5 min. Nevertheless, they were found to be largely composed of protein (91%, based on total nitrogen). The major amino acids in acid hydrolysates were aspartic acid, glycine, serine, alanine, half-cystine, and valine. Glucosamine was not detected in acid hydrolysates. The sulfur content was 2.5%, and this could be accounted for in half-cystine and methionine. Carbohydrate comprised just over 2%. The phosphorus content was 0.21%, of which less than one-third was accounted for in phospholipid. The total fatty acid content was 1.0%, most of which could be accounted for by the fatty acids of the phospholipids.
Deoxyribonucleic acid repair capacities of Neisseria gonorrhoeae: absence of photoreactivation
Authors: Campbell L A , Yasbin R E
Published: January 2020

No difference in survival was observed when ultraviolet-irradiated gonococcal cells were subsequently incubated in the dark or exposed to photoreactivating light. This observation indicates that photoreactivation is absent in Neisseria gonorrhoeae.
Response of Pseudomonas cepacia to beta-Lactam antibiotics: utilization of penicillin G as the carbon source
Authors: Beckman W , Lessie T G
Published: January 2020

Pseudomonas cepacia utilized penicillin G as the sole source of carbon and energy. We report here an unexplained correlation between lysine auxotrophy and beta-lactamase deficiency, resulting in loss of capacity to utilize penicillin.
Allantoate transport in Saccharomyces cerevisiae
Authors: Turoscy V , Cooper T G
Published: January 2020

Allantoate uptake appears to be mediated by an energy-dependent active transport system with an apparent Michaelis constant of about 50 microM. Cells were able to accumulate allantoate to greater than 3,000 times the extracellular concentration. The rate of accumulation was maximum at pH 5.7 to 5.8. The energy source for allantoate uptake is probably different from that for uptake of the other allantoin pathway intermediates. The latter systems are inhibited by arsenate, fluoride, dinitrophenol, and carboxyl cyanide-m-chlorophenyl hydrazone, whereas allantoate accumulation was sensitive to only dinitrophenol and carboxyl cyanide-m-chlorophenyl hydrazone. Efflux of preloaded allanotate did not occur at detectable levels. However, exchange of intra- and extracellular allantoate was found to occur very slowly. The latter two characteristics are shared with the allantoin uptake system and may result from the sequestering of intracellular allantoate within the cell vacuole. During the course of these studies, we found that, contrary to earlier reports, the reaction catalyzed by allantoinase is freely reversible.
Relationship Between Cell Size and Efficiency of Synchronization During Nitrogen-Limited Phased Cultivation of
Candida utilis
Authors: Thomas K. Chandapillai , Dawson Peter S. S. , Gamborg Brian L. , Steinhuer Lee
Published: January 2020

Under the phased method of cultivation the yeast
Candida utilis
grew and divided synchronously. The newly formed cells were relatively small, and a new cell cycle was not initiated until the cells could attain a certain minimum size (critical size). Although the cells expanded to some extent after division, the critical size was not reached until a fresh supply of medium was provided. With the arrival of the fresh supply of growth medium at the beginning of the phasing period, the cells expanded rapidly, and new cell cycles were initiated. The cells continued to expand until the growth-limiting nutrient (nitrogen source) was exhausted or until 90 min, which ever occurred first. Usually, buds emerged at a constant time after the start of the phasing period. The time of bud emergence was independent of the size attained by the cells during the expansion phase of growth. The results indicated that it was initiation of the cell cycle that was under size control, and not bud emergence. Bud emergence seemed to be under the control of a timer. The start of this timer seemed to be at or immediately after the beginning of the phasing period. Protein synthesis was essential for the initiation and expansion of buds. However, inhibition of protein synthesis by cycloheximide did not prevent unbudded cells or the parent portion of budded cells from expanding. Cycloheximide seemed to abolish the control mechanism(s) which prevented the cells from expanding after they had reached the maximum size.
Site-specific recombination between plasmids of Staphylococcus aureus
Authors: Murphy E , Novick R P
Published: January 2020

Anomalous recombination between two similar but nonidentical, naturally occurring penicillinase plasmids, pI258 and pI524, leading to duplication and deletion of the beta-lactamase locus, is described. Physical mapping of these plasmids by heteroduplex and restriction analysis revealed that the beta-lactamase loci were homologous and in inverted orientation with respect to one another and that their respective locations were separated by a short region of homology. This intervening region of homology included one copy of a segment that was repeated on pI524 in inverted orientation at a distance of 2.2 kilobase pairs and contained a recognition sequence for a site-specific, rec-independent recombination function that caused reversible inversion of this segment on pI524. It is proposed that site-specific, intermolecular recombination involving this repeated sequence was responsible for the observed results.
Biological properties of two distinct pilus types produced by isogenic variants of Neisseria gonorrhoeae P9
Authors: Lambden P R , Robertson J N , Watt P J
Published: January 2020

Isogenic variants from a single strain of Neisseria gonorrhoeae were shown to produce two distinct types of pili. These pili, designated alpha and beta, differed in both subunit molecular weight and in ability to attach to buccal epithelial cells.
Mutation affecting expression of spectinomycin resistance in Bacillus subtilis
Authors: Cannon J G , Bott K F
Published: January 2020

A mutation that affects the expression of spectinomycin resistance in a spectinomycin-resistant (spcA), conditionally asporogenic strain of Bacillus subtilis has been designated srm (spectinomycin resistance modifier). This mutation resulted in altered colony morphology and increased growth rate and sporulation efficiency in the presence of spectinomycin.
Regulation of ornithine decarboxylase during morphogenesis of Mucor racemosus
Authors: Inderlied C B , Cihlar R L , Sypherd P S
Published: January 2020

During the yeast-to-hyphae transition of the dimorphic phycomycete Mucor racemosus, there was a 30- to 50-fold increase in the activity of ornithine decarboxylase. Increased enzyme activity preceded the emergence of germ tubes and reached a maximum before conversion was completed. Subsequently, enzyme levels rapidly declined, despite the continuation of mycelial growth. Both putrescine and spermidine blocked the enzyme activity response. Protein synthesis was required for the increase in enzyme activity during morphogenesis. A combination of actinomycin D and netropsin inhibited ribonucleic acid synthesis but failed to inhibit the increase in ornithine decarboxylase activity. There was a twofold increase in the enzyme half-life during morphogenesis with either trichodermin or verrucarin to inhibit protein synthesis.
Determination of pili by conjugative bacterial drug resistance plasmids of incompatibility groups B, C, H, J, K, M, V, and X
Authors: Bradley D E
Published: January 2020

Representative plasmids from incompability groups B, C, H, J, K, M, V, and X were transferred to "bald" strains of Escherichia coli or Salmonella typhimurium. By using a new technique, pili were detected by electron microscopy for each incompatibility group. Morphology varied but was similar for plasmids within a group. These findings suggest that all conjugative plasmids in the Enterobacteriaceae may determine pili.
Physical characterization of plasmids determining synthesis of a microcin which inhibits methionine synthesis in Escherichia coli
Authors: Perez-Diaz J C , Clowes R C
Published: January 2020

Plasmid deoxyribonucleic acid (DNA) isolated from each of three antibiotic-resistant clinical strains of Escherichia coli producing the same microcin showed multiple bands upon agarose gel electrophoresis. Transformants selected either for microcin resistance or ampicillin resistance yielded plasmid DNA corresponding in size to only one of the multiple bands. Plasmids, isolated from all three hosts, which determined microcin resistance and microcin production measured about 4 megadaltons by sucrose density, restriction enzyme, and contour length analyses; cleavage of the DNAs by each of eight restriction enzymes showed the same response, and DNA-DNA hybridization indicated complete homology. The antibiotic resistance plasmids of the three host strains were uniformly larger, were of different sizes, and showed different restriction enzyme cleavage patterns. One of these R plasmids (pCP106) also determined the synthesis of the same microcin, and DNA-DNA hybridization studies indicated an approximate 2.4-megadalton homology with the 4-megadalton microcin plasmid pCP101. The microcin plasmids were present at approximately 20 copies per genome equivalent and were nonconjugative, whereas the R plasmids had a copy number of about 1, were conjugative, and could mobilize the microcin plasmid. Microcin plasmid pCP101 showed replication properties similar to those of a number of small multicopy plasmids such as ColE1.
Identification and mapping of a second proline permease Salmonella typhimurium
Authors: Menzel R , Roth J
Published: January 2020

In this paper we demonstrate the existence of a second proline permease, gene proP, in Salmonella typhimurium. Uptake assays demonstrate that this second proline permease has 5 to 10% the uptake rate of the putP permease, the cell's major proline permease, when assayed at 20 microM proline. Genetic mapping by Hfr and P22-mediated genetic crosses placed the second proline permease gene at 92 min on the S. typhimurium genetic map, near the genes for melibiose utilization. F'-mediated complementation tests indicated that Escherichia coli also has the proP gene.