bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of temperature on translocation frequency of the Tn3 element
Authors: Kretschmer P J , Cohen S N
Published: January 2020

The effect of temperature on the translocation frequency of the Tn3 element was investigated. The temperature optimum for translocation of Tn3 was in the range from 26 to 30 degrees C. At temperatures above 30 degrees C, the translocation frequency decreased rapidly and linearly; at 36 degrees C it was only 5% of the frequency observed at 30 degrees C. The duration and reversibility of the temperature effect were utilized to demonstrate a requirement for protein synthesis in the translocation process.
Adenine inhibition of the synthesis of photosynthetic membranes in the chloroplast of Scenedesmus obliquus grown in the dark
Authors: Abeliovich A , Dickbuk S
Published: January 2020

In the presence of adenine, heterotrophically grown Scenedesmus obliquus lost most of its photosynthetic membranes. The rudimentary membranes appeared to be intact both functionally and morphologically.
Microbial oxidation of gaseous hydrocarbons. II. Hydroxylation of alkanes and epoxidation of alkenes by cell-free particulate fractions of methane-utilizing bacteria
Authors: Patel R N , Hou C T , Laskin A I , Felix A , Derelanko P
Published: January 2020

Cell-free particulate fractions derived from methylotrophic bacteria catalyze the oxygen- and reduced nicotinamide adenine dinucleotide-dependent epoxidation of alkenes and hydroxylation of alkanes. Evidence presented indicates that the hydroxylation and epoxidation reactions are catalyzed by the same or a similar metal-containing monooxygenase.
Introduction of bacteriophage lambda into cells of Klebsiella aerogenes
Authors: Bloom F R , Tyler B
Published: January 2020

We have shown that a mutation in the cro gene of phage lambda greatly reduces zygotic induction. This observation has allowed us to move this phage on an episome into cells of Klebsiella aerogenes where it grows as well as in cells of Escherichia coli. This technique should allow the introduction of various derivatives of lambda into any organism which is able to receive deoxyribonucleic acid from E. coli.
Insertional Inactivation of
trpC
in Cloned
Bacillus trp
Segments: Evidence for a Polar Effect on
trpF
Authors: Keggins K. M. , Lovett P. S. , Marrero R. , Hoch S. O.
Published: January 2020

Plasmid pUB110 was previously used as a vector to clone fragments of deoxyribonucleic acid that complement the
trpC2
mutation in
Bacillus subtilis
from endonuclease
Eco
RI digested
B. licheniformis, B. pumilus
, and
B. subtilis
cellular deoxyribonucleic acid. Each of several such
trp
plasmids was subsequently shown to contain a segment of the
trp
gene cluster on the basis of genetic complementing activity. In the present study, analysis of the Trp enzyme levels in
B. subtilis
harboring the constructed
trp
plasmids confirms the genetic constitution of the plasmids. Thus, plasmids that complement mutations in specific
trp
genes specify the corresponding enzyme activities. The levels of the plasmid-specified Trp enzymes in
B. subtilis
were generally above the repressed level of the chromosomally specified Trp enzymes and equal to or below the derepressed levels of the chromosomally specified Trp enzymes. Certain cloned
trp
segments contain a single
Hin
dIII-sensitive site. Insertion of
Hin
dIII-generated deoxyribonucleic acid fragments into these
trp
plasmids resulted in inactivation of
trpC
complementing activity, loss of the
trpC
-specified enzyme activity, and a 10-fold reduction in the specific activity of the plasmid-specified
trpF
product. The
Hin
dIII insertions had no detectable effect on the level of the
trpD
product, nor did the insertions detectably alter plasmid-specified complementing activity other than to abolish
trpC
complementation. Removal of the
Hin
dIII insertions was accompanied by recovery of
trpC
complementing activity and restoration of the
trpC
-and
trpF
-determined enzymes to the levels specified by the parent plasmids.
Effect of glucose on polyol metabolism by Rhizobium trifolii
Authors: Ronson C W , Primrose S B
Published: January 2020

The effect of glucose on polyol metabolism by Rhizobium trifolii was studied. Phenomena similar to catabolite repression and catabolite inhibition were observed. The catabolism of glucose to at least glucose 6-phosphate was required for the effects to be exerted.
his-Linked hydrogen sulfide locus of Salmonella typhimurium and its expression in Escherichia coli
Authors: Voll M J , Cohen L A , Germida J J
Published: January 2020

A his-linked H2S locus of Salmonella typhimurium has been further defined by direct isolation of H2S mutants. Expression of this locus in Escherichia coli has been demonstrated.
recE4-Independent recombination between homologous deoxyribonucleic acid segments of Bacillus subtilis plasmids
Authors: Tanaka T
Published: January 2020

A plasmid (pLS104) carrying a tandem repetition of the leu region of the Bacillus subtilis chromosome arose spontaneously from pLS103, which carried a single copy of the leu region. Plasmid preparations from strains harboring pLS104 also contained the original plasmid, pLS103, and, in some preparations, plasmids carrying three or four repetitions of the leu region. These plasmids were shown to be generated by recombination between homologous deoxyribonucleic acid (DNA) segments in the tandemly repeated DNA regions on the plasmids, but not by recombinations between specific DNA sites. These phenomena were observed in a recE4-Independent background, showing that recombination of the homologous DNA sequences does not require the recE-Independent gene product(s).
Consequences of Ca2+ deficiency on macromolecular synthesis and adenylate energy charge in Yersinia pestis
Authors: Zahorchak R J , Charnetzky W T , Little R V , Brubaker R R
Published: January 2020

A 37 but not 26 degrees C virulent Yersinia pestis is known to require at least 2.5 mM Ca2+ for growth; this requirement is potentiated by Mg2+. After shift of log-phase cells (doubling time of 2 h) from 26 to 37 degrees C in Ca2+-deficient medium, shutoff of net ribonucleic acid synthesis preceded that of protein and cell mass. With 2.5 mM Mg2+, about two doublings in cell mass and number occurred before restriction with synthesis of sufficient deoxyribonucleic acid to account for initiation and termination of two postshift rounds of chromosome replication. Temperature shift with 20 mMMg2+ resulted in a single doubling of cell mass and number with one round of chromosome replication. Subsequent to shutoff of ribonucleic acid accumulation, ribonucleoside but not deoxyribonucleoside triphosphate pools became reduced to about 50% of normal values and the adenylate energy change fell from about 0.8, typical of growing cells, to about 0.6. Excretion of significant concentrations of adenine nucleotides under both permissive and restrictive conditions was observed. Only trace levels (less than 0.01 microM ol/g [dry weight]) of guaninosine 5'-diphosphate 3'-diphosphate accumulated under restrictive or permissive conditions; guanosine 5'-triphosphate 3'-diphosphate was not detected. Return of fully restricted cells from 37 to 26 degrees C with Ca2+ resulted in prompt growth, whereas addition of Ca2+ at 37 degrees C was ineffective. This finding indicates that the observed temperature-sensitive lesion in ribonucleic acid synthesis that results in restriction can be prevented but not reversed by cultivation with Ca2+.
Oxalurate transport in Saccharomyces cerevisiae
Authors: Cooper T G , McKelvey J , Sumrada R
Published: January 2020

Oxalurate, the gratuitous inducer of the allantoin degradative enzymes, was taken into the cell by an energy-dependent active transport system with an apparent Km of 1.2 mM. Efflux of previously accumulated oxalurate was rapid, with a half-life of about 2 min. The oxalurate uptake system appears to be both constitutively produced and insensitive to nitrogen catabolite repression. The latter observations suggest that failure of oxalurate to bring about induction of allophanate hydrolase in cultures growing under repressive conditions does not result from inducer exclusion, but rather from repression of dur1,2 gene expression.
Mutation spoT of Escherichia coli increases expression of the histidine operon deleted for the attenuator
Authors: Winkler M E , Zawodny R V , Hartman P E
Published: January 2020

F'-episomes carrying the Salmonella typhimurium wild-type or attenuator-deleted histidine (his) operons were introduced into Escherichia coli strains containing relA or spoT single and double mutations known to affect guanosine 3'-diphosphate 5'-diphosphate (ppGpp) and guanosine 3'-triphosphate 5'-diphosphate (pppGpp) levels. Expression of the his operon and expression of the gene for 6-phosphogluconate dehydrogenase (gnd) were measured during balanced growth in amino acid-rich and minimal media. The data were consistent with the interpretation that ppGpp is a positive effector of his operon expression, whereas pppGpp is not an essential effector. The conclusion that his operon expression is maximally stimulated at a lower than maximum intracellular ppGpp concentration was further confirmed. Neither ppGpp nor pppGpp appeared to influence gnd gene expression. The metabolic regulation of the E. coli his operon was found to be similar to the ppGpp-meidated metabolic regulation of the S. typhimurium his operon.
Structural and functional analysis of cloned deoxyribonucleic acid containing the trpR-thr region of the Escherichia coli chromosome
Authors: Gunsalus R P , Zurawski G , Yanofsky C
Published: January 2020

Specialized transducing phages containing the thr-trpR region of the Escherichia coli chromosome were derived from a strain with lambda prophage inserted in thr. Cloning of segments of the chromosomal deoxyribonucleic acid of one such lambda thr + trpR+ phage in various plasmid vectors established that a 1.3-kilobase BamHI fragment carried trpR+ intact. Strains with a multicopy plasmid vector containing the BamHI insert produced 20-fold-higher levels of trp aporepressor than did the wild-type strain of Escherichia coli. Similarly, induction of lambda thr + trpR+ lysogens resulted in increased aporepressor levels. The 1.3-kilobase trpR+ BamHI fragment was inserted in either orientation downstream from lambda pLN in a plasmid vector in which transcription from lambda pL was under the control of a temperature-sensitive lambda repressor. Induction established the orientation of transcription of trpR and led to the production of 100-fold-increased levels of trp aporepressor. A presumptive 23,500-dalton trpR+ polypeptide was detected by using lambda pLNtrpR+ plasmid deoxyribonucleic acid in a cell-free transcription-translation system.
Scanning electron microscopy of surface ultrastructure changes during meiosporangium maturation and meiospore liberation in the aquatic fungus Allomycpes arbuscula
Authors: Seale T W , Runyan R B
Published: January 2020

Alterations in wall ultrastructure accompanying resistant sporangium maturation and meiospore liberation in Allomyces arbuscula were examined by scanning electron microscopy. Three discrete wall layers were identified, each of which underwent marked changes during processes leading to zoospore release. The outermost wall layer, the hyphal sheath continuous with the hypha, was physically altered during the maturation process preparatory to induction and release of meiospores. The integrity of this wall layer was broken, and it was no longer closely juxtaposed to the heavy pitted wall layer that lay beneath it. A fibrillar matrix seemed to cement the two layers to one another before this desiccation. A single, raised, longitudinal dehiscence ridge on each meiosporangium appeared to be a structurally differentiated region of the pitted wall layer at which sporangium rupture occurred to permit emergence of the protoplast. By its thickness the pitted wall layer was likely to provide mechanical rigidity to the meiosporangium. Beneath the pitted wall layer, another thin, flexible wall layer surrounded the protoplast. From this structure, a single exit papilla was cleaved at the apical region to effect the release of meiospores from the protruding protoplast. Thus a sequence of structural changes in well-differentiated multiple wall layers is implicated in the sporulation process in this organism.
Scanning electron microscope study of Saccharomyces cerevisiae spheroplast formation
Authors: Pringle A T , Forsdyke J , Rose A H
Published: January 2020

A suspension of Saccharomyces cerevisiae NCY366 in buffered 1.2 M sorbitol containing Zymolyase-5000 (a beta-glucanase-containing preparation/showed maximum osmotic sensitivity after 30 min of incubation at 30 degrees C. A scanning electron microscope study of spheroplast formation, using a very high resolution (4-nm) machine, revealed several new morphological features. The surface of the plug in bud scars on intact cells appeared warty. The wall, which assumed a beady appearance as digestion proceded, ultimately sloughed off to reveal the furrowed surface of the plasma membrane. Bud scars were resistant to digestion and. as incubation proceeded, they became surrounded by an outer annulus, which may be the seconary septum. Wall material was completely removed from the majority of cells only after 60 min of digestion. The surface of spheroplasts was studded with particles, about 25 to 30 nm in diameter. Many spheroplasts had a single large indentation, which may be in that part of the plasma membrane originally underlying the birth scar.
Transformation and transfection of Pseudomonas aeruginosa: effects of metal ions
Authors: Mercer A A , Loutit J S
Published: January 2020

The ability of different metal ions to promote transformation of Pseudomonas aeruginosa by deoxyribonucleic acid of the plasmid RP1 was examined. CaCl2, MgCl2, and MnCl2 were found to promote such transformation, although at different frequencies and with the optimum response at different concentrations. Only MgCl2 promoted transfection of P. aeruginosa by the linear deoxyribonucleic acid of phage F116. CaCl2 was demonstrated to allow adsorption and entry into the cell of F116 deoxyribonucleic acid such that it became resistant to exogenous deoxyribonuclease, but phage production occurred only when MgCl2 was provided. Inactivation of linear phage deoxyribonucleic acid taken up in the absence of MgCl2 was observed. The transfection frequencies at various concentrations of MgCl2 were compared, and the optimum response occurred at the concentration which promoted the highest frequency of transformation by RP1 deoxyribonucleic acid.
Deoxyribonucleic acid and outer membrane: binding to outer membrane involves a specific protein
Authors: Wolf-Watz H , Norqvist A
Published: January 2020

The binding of deoxyribonucleic acid (DNA) to the outer membrane of Escherichia coli was examined. The amount of DNA found to be bound to outer membrane was low and was estimated to be about 0.4% of the total DNA. Treatment of cells with chloramphenicol or rifampin caused a disassociation of the apparent DNA-outer membrane complex. The results presented here suggest that the binding between membrane and DNA is specific and involves a membrane protein having a molecular weight of 13,000.
A new gene of Escherichia coli K-12 whose product participates in T4 bacteriophage late gene expression: interaction of lit with the T4-induced polynucleotide 5'-kinase 3'-phosphatase
Authors: Cooley W , Sirotkin K , Green R , Synder L
Published: January 2020

We isolated five Escherichia coli mutants deficient in their ability to support the late (replication-coupled) gene expression of T4 bacteriophage at 30 degrees C. These mutants, which we call Lit mutants, define at least one novel gene at 25 min on the E. coli map. They were selected in an attempt to obtain mutants which restrict the growth of T4 mutants deficient in polynucleotide 5'-kinase 3'-phosphatase but not that of wild-type T4 at 37 degrees C. Some of the mutants do have these phenotypes under some conditions. Studies of the block in T4 development in some of the E. coli mutants suggest that Lit mutants are affected in a gene product involved in the metabolism of deoxyribonucleic acid nicks or single-strand gaps. None of the Lit mutants is deficient in the major, bacterial, 3'-phosphatase activity in crude extracts.
Cyclic adenosine 3',5'-monophosphate regulation of the bacteriophage T6/colicin K receptor in Escherichia coli
Authors: Alderman E M , Dills S S , Melton T , Dobrogosz W J
Published: January 2020

Mutant strains of Escherichia coli unable to synthesize cyclic adenosine 3',5'-monophosphate (cAMP) or the cyclic adenosine monophosphate receptor protein (CRP) were more resistant than wild-type cells to infection by bacteriophage T6. This resistance was found to be associated with the decreased production of specific T6 receptor protein (also the colicin K receptor) located in the outer membrane protein fraction of these cells. Transcription of this particular outer membrane protein was regulated by the cAMP-CRP complex. A novel affinity technique coupled with sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used in these investigations.
Production and excretion of cloacin DF13 by Escherichia coli harboring plasmid CloDF13
Authors: Van Tiel-Menkvled G J , Rezee A , De Graaf F K
Published: January 2020

The production and the mechanism of excretion of cloacin DF13 were investigated in noninduced and mitomycin C-induced cell cultures. A mitomycin C concentration was selected which did not cause lysis of cloacinogenic cells, but at the same time induced a maximal production of cloacin DF13. Native cloacin DF13, possessing killing activity, was first released into the cytoplasm. Shortly thereafter, the bacteriocin was transported through the cytoplasmic membrane and accumulated in the periplasm. Finally, cloacin DF13 was excreted into the culture medium. A small amount of cloacin DF13 remained associated with the cell surface. Producing cells did not become permeable for the cytoplasmic enzyme beta-galactosidase. Apparently the cloacin DF13 leaves the producing cells by an excretion process which is not similar to the mechanism proposed for bacterial secretory proteins. The processes of excretion by producing cells and of uptake by susceptible cells were also not identical because mutant cloacin DF13, which was not transported through the outer membrane into susceptible cells, was excreted like the wild-type cloacin DF13. The composition of the culture medium greatly affected production of cloacin DF13. The presence of sugars known to cause catabolite repression not only inhibited the production but also strongly reduced the excretion of cloacin DF13 into the culture medium.
Effect of blocking protein synthesis at nonpermissive temperatures on temperature-sensitive deoxyribonucleic acid mutants of Escherichia coli
Authors: Evans I M , Forrest N , Lawrence A , Eberle H
Published: January 2020

When protein synthesis was blocked in temperature-sensitive deoxyribonucleic acid synthesis mutants of Escherichia coli at nonpermissive temperatures, it reduced the amount of apparent subsequent chain elongation to approximately half that observed in the mutants either at nonpermissive temperatures alone or when protein synthesis was blocked at the permissive temperature. Blocking protein synthesis at the nonpermissive temperatures for periods of 40 min caused the loss of ability to reinitiate deoxyribonucleic acid synthesis at the permissive temperature.
Mechanism of acetate synthesis from CO2 by Clostridium acidiurici
Authors: Waber L J , Wood H G
Published: January 2020

Total synthesis of acetate from CO2 by Clostridium acidiurici during fermentations of hypoxanthine has been shown to involve synthesis of glycine from methylenetetrahydrofolate, CO2, and NH3. The glycine is converted to serine by the addition of methylenetetrahydrofolate, and the resulting serine is converted to pyruvate, which is decarboxylated to form acetate. Since CO2 is converted to methylenetetrahydrofolate, both carbons of the acetate are derived from CO2. The evidence supporting this pathway is based on (i) the demonstration that glycine decarboxylase is present in C. acidiurici, (ii) the fact that glycine is synthesized by crude extracts at a rate which is rapid enough to account for the in vivo synthesis of acetate from CO2, (iii) the fact that methylenetetrahydrofolate is an intermediate in the formation of both carbons of acetate from CO2, and (iv) the fact that the alpha carbon of glycine is the source of the carboxyl group of acetate. Evidence is presented that this synthesis of acetate does not involve carboxylation of a methyl corrinoid enzyme such as occurs in Clostridium thermoaceticum and Clostridium formicoaceticum. Thus, there are two different mechanisms for the total synthesis of acetate from CO2 by clostridia.
Lambda transducing bacteriophage carrying deletions of the argCBH-rpoBC region of the Escherichia coli chromosome
Authors: Linn T , Goman M , Scaife J
Published: January 2020

Deletions in the rpoBC region have been transferred to phage lambda and characterized in detail by genetic, structural, and functional tests. We thus extend and confirm knowledge of the organization of this part of the chromosome. The new phages are useful tools for studying the genes for the bacterial transcription and translation machinery.
Electron acceptor taxis and blue light effect on bacterial chemotaxis
Authors: Taylor B L , Miller J B , Warrick H M , Koshland D E
Published: January 2020

Salmonella typhimurium and Escherichia coli from anaerobic cultures displayed tactic responses to gradients of nitrate, fumarate, and oxygen when the appropriate electron transport pathway was present. Such responses were named "electron acceptor taxis" because they are elicited by terminal electron acceptors. Mutant strains of S. typhimurium and E. coli were used to establish that functioning electron transport pathways to nitrate and fumarate are required for taxis to these compounds. Aerotaxis in S. typhimurium was blocked by 1.0 mM KCN, which inhibited oxygen uptake. Similarly, a functioning electron transport pathway was shown to be essential for the tumbling response of S. typhimurium and E. coli to intense light (290 to 530 nm). Some inhibitors and uncouplers of respiration were repellents of S. typhimurium. We propose that behavioral responses to light or electron acceptors involve electron transport-mediated perturbations of the proton motive force.
Pyridine nucleotide cycle of Salmonella typhimurium: in vitro demonstration of nicotinamide mononucleotide deamidase and characterization of pnuA mutants defective in nicotinamide mononucleotide transport
Authors: Kinney D M , Foster J W , Moat A G
Published: January 2020

The enzyme nicotinamide mononucleotide deamidase, an integral component of the proposed four-membered pyridine nucleotide cycle (PNC IV), has been demonstrated in extracts of Salmonella typhimurium LT2. The enzyme has an optimum pH of 8.7 and deamidates nicotinamide mononucleotide, forming nicotinic acid mononucleotide. Sigmoidal kinetic data suggest that this enzyme may be allosteric and therefore an important regulatory component of pyridine nucleotide cycle metabolism. Mutants previously designated pncC in anticipation of their lacking nicotinamide mononucleotide deamidase were examined and found to have normal levels of this enzyme. [14C]nicotinamide mononucleotide uptake studies, however, revealed a defect in the transport of this compound. Accordingly, the genetic designation for this locus was changed to pnuA to reflect its involvement in pyridine nucleotide uptake. Evidence is presented for the existence of two separate nicotinamide mononucleotide transport systems.
Polyamine biosynthesis during germination of yeast ascospores
Authors: Brawley J V , Ferro A J
Published: January 2020

The role of the diamine putrescine during germination and outgrowth of ascospores of Saccharomyces cerevisiae was examined. Ornithine decarboxylase activity increased and declined rapidly during germination and outgrowth; peak activity was attained after the cells had proceeded through the G1 interval of the cell cycle, whereas minimal activity was present at the completion of the first cell division. alpha-Methylornithine inhibited both ornithine decarboxylase activity and the in vivo accumulation of putrescine. In the presence of alpha-methylornithireak dormancy and proceed through one cell division. Subsequent cellular growth, however, was retarded but not completely inhibited. The supplementation of Methylglyoxal bis(guanylhydrazone) to sporulation medium greatly inhibited this sexual process. These data suggest that the synthesis of putrescine is not required for the breaking of spore dormancy, but that polyamine biosynthesis may be essential for meiosis and sporulation.
Transformation in pneumococcus: nuclease resistance of deoxyribonucleic acid in the eclipse complex
Authors: Morrison D A , Mannarelli B
Published: January 2020

Donor deoxyribonucleic acid strands in the eclipse phase of genetic transformation of pnuemococcus (Streptococcus pneumoniae) are purified as a complex with a cf the deoxyribonucleic acid strand in this complex to digestion by nucleases was shown to be 50- to 1,000-fold less than that of uncomplexed single strands of deoxyribonucleic acid. Deoxyribonuclease I, micrococcal nuclease, Neurospora endonuclease, nuclease P1, and the major endogenous nuclease of cell-free extracts were studied. Sensitivity to nuclease attack was not uniform along the deoxyribonucleic acid strand; sequences of strongly protected bases were separated by more sensitive regions. The minimum size of protected fragments was about 70 bases. A complex of protein with the protected deoxyribonucleic acid segments was obtained after partial digestion. The sizes of these complexes, of the protected deoxyribonucleic acid segments, and of the protein subunit released by complete nuclease digestion, are all approximately identical, as determined by gel exclusion chromatography. Deoxyribonucleic acid strands of eclipse complex were also shown to be particularly well protected from attack by the major pneumococcal endonuclease in cell extracts.
Electron microscopy of the rodlet layer of Neurospora crassa conidia
Authors: Dempsey G P , Beever R E
Published: January 2020

Neurospora crassa macroconidia possess a regularly arranged layer of small fibers (rodlets) near the spore surface. The structure and location of this layer were studied by making surface replicas, by negative staining, by freeze-fracturing and deep-etching, and by thin sectioning. When conidia were shaken vigorously in water, the layer fragmented and became separated from the surface in sheets. Negative staining of such sheets showed that the individual rodlets have a hollow central core. When conidia were shaken gently in water or fixative, large fragments of the rodlet layer often remained on the conidial surface. The fragments tended to fold back on each other such that multiple layers were sometimes seen in thin sections. It is concluded that in dry conidia the rodlets are located on the extreme outside of the spore where they form a monolayer with only occasional regions of overlap.
Chemiosmotic coupling in Methanobacterium thermoautotrophicum: hydrogen-dependent adenosine 5'-triphosphate synthesis by subcellular particles
Authors: Doddema H J , van der Drift C , Vogels G D , Veenhuis M
Published: January 2020

Hydrogenase and the adenosine 5'-triphosphate (ATP) synthetase complex, two enzymes essential in ATP generation in Methanobacterium thermoautotrophicum, were localized in internal membrane systems as shown by cytochemical techniques. Membrane vesicles from this organism possessed hydrogenase and adenosine triphosphatase (ATPase) activity and synthesized ATP driven by hydrogen oxidation or a potassium gradient. ATP synthesis depended on anaerobic conditions and could be inhibited in membrane vesicles by uncouplers, nigericin, or the ATPase inhibitor N,N'-dicyclohexylcarbodiimide. The presence of an adenosine 5'-diphosphate-ATP translocase was postulated. With fluorescent dyes, a membrane potential and pH gradient were demonstrated.
Isolation of temperature-sensitive pantothenate kinase mutants of Salmonella typhimurium and mapping of the coaA gene
Authors: Dunn S D , Snell E E
Published: January 2020

Temperature-sensitive pantothenate kinase mutants of Salmonella typhimurium LT2 were selected by using the excretion of pantothenate at the nonpermissive temperature as a screening method. Thermolability of the pathothenate kinase activity in extracts of the mutants was demonstrated. The mutations were mapped at min 89 of the Salmonella chromosome, near rpoB, by transduction. As pantothenate kinase catalyzes the first step in the biosynthesis of coenzyme A from pantothenate, the new genetic locus has been designated coaA.
Carbamyl phosphate synthetase A of Neurospora crassa
Authors: Davis R H , Ristow J L , Hanson B A
Published: January 2020

Carbamyl phosphate synthetase A of Neurospora crassa was partially purified from mitochondrial extracts. It is an extremely unstable enzyme (t 1/2 = 45 min at 25 detrees C) made up of two unequal subunits. The native enzyme has a molecular weight of approximately 175,000, and the large subunit has a molecular weight of about 125,000. Both the native enzyme and its large subunit are quite asymmetric, as revealed by slow sedimentation in sucrose gradents (7.3S and 6.6S, respectively). The small subunit has not been identified physically as a separate entity. The denaturation of the native, glutamine-dependent activity is correlated with dissociation of subunits, the larger of which retains a more stable, ammonia-dependent activity. Neither substrates nor any other agents except glycerol or polyethylene glycol appreciably stabilized the glutamine-dependent activity. Kinetic studies showed the native enzyme to have a Km for glutamine of about 0.16 mM, and a Km for NH4Cl of about 16 mM, at the optimal pH, 8.0. The enzyme, using either N donor, has a K+ requirement for activity, for which NH4+ can substitute. The glutamine leads to glutamate reaction, which requires the small subunit, also requires the large subunit and all reaction substrates for optimal activity. Other evidences of subunit interaction are the greater activity of the native enzyme, as opposed to the large subunit, with low concentrations of adenosine 5'-triphosphate-Mg2+, and in the stimulation of the ammonia-dependent activity of the native enzyme by glycine. Curiously, although the enzyme's role in biosynthesis is confined to the arginine pathway, it is completely indifferent to arginine or its precursors as feedback effectors or activators. The enzyme is compared with carbamyl phosphate synthetases of other organisms.
Salmonella typhimurium
Mutants with Altered Glutamate Dehydrogenase and Glutamate Synthase Activities
Authors: Dendinger Susan M. , Patil Lalita G. , Brenchley Jean E.
Published: January 2020

Although glutamate is a key compound in nitrogen metabolism, little is known about the function or regulation of its two biosynthetic enzymes, glutamate dehydrogenase and glutamate synthase. To begin the characterization of glutamate formation in
Salmonella typhimurium
, we isolated mutants having altered glutamate dehydrogenase and glutamate synthase activities. Mutants which failed to grow on media with glucose as the carbon source and less than 1 mM (NH
4
)
2
SO
4
as the nitrogen source (Asm
−
) had about one-fourth the normal glutamate synthase activity and one-half the glutamine synthetase activity. The
asm
mutations also prevented growth with alanine, arginine, or proline as nitrogen sources and conferred resistance to methionine sulfoximine. When a mutation (
gdh-51
) causing the loss of glutamate dehydrogenase activity was transferred into a strain with an
asm-102
mutation, the resulting
asm-102 gdh-51
mutant had a partial requirement for glutamate. A strain isolated as a complete glutamate auxotroph had a third mutation, in addition to the
asm-102 gdh-51
lesions, that further decreased the glutamate synthase activities to 1/20 the normal level. Both the
asm-102
and
gdh-51
mutations were located on the
S. typhimurium
linkage map at sites distinct from those found for mutations causing similar phenotypes in
Klebsiella aerogenes
and
Escherichia coli
.
Effect of Carbon Source on Enzymes and Metabolites of Arginine Metabolism in
Neurospora
Authors: Drainas Constantin , Weiss Richard L.
Published: January 2020

The levels of enzymes and metabolites of arginine metabolism were determined in exponential cultures of
Neurospora crassa
grown on various carbon sources. The carbon sources decreased in effectiveness (as determined by generation times) in the following order: sucrose, acetate, glycerol, and ethanol. The basal and induced levels of the catabolic enzymes, arginase (EC 3.5.3.1) and ornithine transaminase (EC 2.6.1.13), were lower in mycelia grown on poor carbon sources. Arginase was more sensitive to variations in carbon source than was ornithine transaminase. Induction of both enzymes was sensitive to nitrogen metabolite control, but this sensitivity was reduced in mycelia grown on glycerol or ethanol. The pools of arginine and ornithine were reduced in mycelia grown in unsupplemented medium containing poor carbon sources, but the biosynthetic enzyme ornithine transcarbamylase (EC 2.1.3.3) was not derepressed. The arginine pools were similar, regardless of carbon source, in mycelia grown in arginine-supplemented medium. The ornithine pool was reduced by growth on poor carbon sources. The rate of arginine degradation was proportional to the level of arginase in both sucrose- and glycerol-grown mycelia. The distribution of arginine between cytosol and vesicles was only slightly altered by growth on glycerol instead of sucrose. The slightly smaller cytosolic arginine concentration did not appear to be sufficient to account for the alterations in basal and induced enzyme levels. The results suggest a possible carbon metabolite effect on the expression or turnover of a variety of genes for enzymes of arginine metabolism in
Neurospora
.
Influence of uvrD3, uvrE502, and recL152 mutations on the phenotypes of Escherichia coli K-12 dam mutants
Authors: Marinus M G
Published: January 2020

The recF143 allele did not alter the phenotypes of dam mutants of Escherichia coli. The uvrD3, uvrE502, and recL152 mutations did alter some of the phenotypes of dam bacteria. It was concluded that the uvrD, uvrE, and recL gene products are involved in the same deoxyribonucleic acid repair pathway as the dam gene product.
Regulation of phosphoglycerate dehydrogenase levels and effect on serine synthesis in Escherichia coli K-12
Authors: McKitrick J C , Pizer L I
Published: January 2020

The level of phosphoglycerate dehydrogenase, the first enzyme in the biosynthetic pathway to serine and glycine, has been studied in Escherichia coli grown under different conditions. The enzyme level was not reduced by growth in a medium which contained the end products of the pathway, nor was it elevated when the growth rates was limited by the supply of serine. Elevation of phosphoglycerate dehydrogenase did not occur when charging of tRNA ser was inhibited by serine hydroxamate. However, phosphoglycerate dehydrogenase levels were subject to regulation. Elevated levels of enzyme activity were observed in merodiploids containing multiple copies of the serA gene, and lowered enzyme levels were found in cells grown on carbon sources other than glucose or when certain amino acids were present in the growth medium. The combined effect of these nutritional changes (carbon source and amino acids) reduced the level of phosphoglycerate dehydrogenase to 10 to 12% of that found in wild-type cells and to about 5% of the level in the merodiploids. By using antibody prepared against purified phosphoglycerate dehydrogenase we established that the decrease in enzyme activity reflected decreased amounts of enzyme protein. Constant intracellular concentrations of 3-phosphoglycerate and serine were found in cells with marked differences in phosphoglycerate dehydrogenase activity, indicating that end product inhibition of phosphoglycerate dehydrogenase activity, rather than the amount of the biosynthetic enzymes, is the major factor in regulating the intracellular concentration of serine.
Genetic mapping of arg1 and arg8 in Saccharomyces cerevisiae by trisomic analysis combined with interallelic complementation
Authors: Hilger F , Mortimer R K
Published: January 2020

Through use of multiply disomic strains, the genes arg1 and arg8 were excluded from all of chromosomes I to XVII except (i) XV and (ii) IX and XV, respectively. Further aneuploid analyses showed that these two genes were on the same chromosome. By tetrad analysis, arg1 was shown to be linked to SUP3 on the left arm of chromosome XV (parental ditype:nonparental ditype:tetratype = 74; 6:139) and arg8 was shown to be loosely linked to arg1 (parental ditype:nonparental ditype:tetratype 72:17:220) on the same arm. The sequence of the genes on this chromosome arm is centromere-SUP3-arg8. Because arg1 had previously been used to define an 18th chromosome, these results reestablished the minimum chromosome number in Saccharomyces cerevisiae as 17.
Electron microscopic mapping of secondary structures in bacterial 16S and 23S ribosomal ribonucleic acid and 30S precursor ribosomal ribonucleic acid
Authors: Edlind T D , Bassel A R
Published: January 2020

Electron microscopy revealed reproducible secondary structure patterns within partially denatured 16S and 23S ribosomal ribonucleic acid (rRNA) from Escherichia coli. When prepared with 50% formamide-100 mM ammonium acetate, 16S rRNA included two small hairpins that appeared in over 50% of all molecules. Three open loops were observed with frequencies of less than 25%. In contrast, 23S rRNA included a terminal open loop and two additional large structures in over 75% of all molecules. These secondary structure patterns were conserved in the 16S and 23S rRNA from Pseudomonas aeruginosa. The secondary structure of the 30S precursor rRNA from the ribonclease III-deficient E. coli mutant AB105 was mapped after partial denaturation in 70% formamide-100 mM ammonium acetate. Two large open loops were superimposed on the 16S and 23S rRNA secondary structure patterns. These loops were the most frequent structures found on the precursor, and their stems coincided with ribonuclease III cleavage sites. A tentative 5'-3 orientation was determined for the secondary structure patterns of 16S and 23S rRNA from their relative locations within 30S precursor rRNA. The relation of secondary structure to ribosomal protein binding and ribonuclease III cleavage is discussed.
Influence of growth conditions on glycine reductase of Clostridium sporogenes
Authors: Venugopalan V
Published: January 2020

Cells of Clostridium sporogenes were deficient in glycine reductase activity when grown in a rich medium containing 40 mM each of exogenously added pyruvate and proline or hydroxyproline. These cells lacked the selenoprotein and at least one more protein of the glycine reductase system. Proline or hydroxyproline in the medium also influenced the uptake of glycine by the cells.
Genetic analysis of Escherichia coli mutants defective in adenylate kinase and sn-glycerol 3-phosphate acyltransferase
Authors: Esmon B E , Kensil C R , Cheng C H , Glaser M
Published: January 2020

Complementation analysis with independently isolated plA and adk (adenylate kinase) mutants of Escherichia coli showed that all the mutants belong to the same complementation group. The results suggest that the adk (plsA) locus is the structural gene for adenylate kinase.
Expression of glycosidase activities during germination of Dictyostelium discoideum spores
Authors: Tisa L S , Cotter D A
Published: January 2020

Several lysosomal glycosidase activities were examined in vitro during heat-induced germination of Dictyostelium discoideum spores and were found not to be coordinately controlled. The level of beta-glucosidase activity increased significantly during the emergence stage of germination. Both alpha-glucosidase and N-acetyl-beta-glucosaminidase activities remained relatively constant until postemergence, when they increased slightly; alpha-mannosidase activity decreased during all stages of germination. The activity of beta-galactosidase increased slightly during spore swelling, fell below the level initially found in spores at zero time, and increased slightly during postemergence. The expression of all of these enzyme activities, except the increase in beta-galactosidase, appeared to require protein synthesis. Spores in the lag phase of germination which were exposed to severe environmental stress were deactivated and exhibited reduced levels of alpha-glucosidase, beta-glucosidase, and N-acetyl-beta-glucosaminidase activities. Prolonged heat activation treatment reduced the levels of lysosomal glycosidase activities in postactivated spores but did not change the subsequent enzyme patterns during the spore-swelling and emergence stages of germination.
Structural specificity of the spermidine requirement of an Escherichia coli auxotroph
Authors: Jorstad C M , Harada J J , Morris D R
Published: January 2020

A homologous series of spermidine analogs was synthesized with the general structure NH3+ (CH2)nNH2+(CH2)3NH3+, where spermidine has n = 4. The influence of these compounds on growth and on the syntheses of protein and messenger ribonucleic acid was examined in a spermidine auxotroph of Escherichia coli. All of the homologs tested were taken up by the cells to an intracellular level equivalent to the level of spermidine which gives optimal growth. With increasing chain length of the homologs, there was reduced ability to stimulate growth. The homologs with n = 7 and n = 8 were essentially inactive. A similar specificity was observed when the ability of the homologs to restore the rates of protein and messenger ribonucleic acid chain elongation was compared to that of spermidine. These results suggest that a definite spatial arrangement of the amino groups of spermidine is required for productive interaction at its intracellular site(s) of action.
Suppression of induction of SOS functions in an Escherichia coli tif-1 mutant by plasmid R100.1
Authors: Bagdasarian M , D'Ari R , Filipowicz W , George J
Published: January 2020

The tif-1 mutation in the recA gene of Escherichia coli caused, at 40 degrees C, lethal cell filamentation, induction of the recA protein, mutagenesis, and, in lambda lysogens, prophage induction. The presence of plasmid R100.1 in tif-1 strains suppressed tif-mediated cell filamentation and killing, recA protein induction, and prophage induction in lysogens. It also reduced mutagenesis in a tif-1 sfiA11(R100.1) strain. Plasmids F'lac, P1, and pMB9, in contrast, had little or no effect on tif-mediated induction of lambda. The presence of R100.1 did not inhibit the induction of the recA protein or of lambda by ultraviolet irradiation or mitomycin C treatment of tif-1(R100.1) or tif-1(lambda)(R100.1) strains.
Regulation of carbohydrate transport activities in Salmonella typhimurium: use of the phosphoglycerate transport system to energize solute uptake
Authors: Saier M H , Feucht B U
Published: January 2020

The phosphoglycerate transport system was employed to supply energy-depleted, lysozyme-treated Salmonella typhimurium cells with a continuous intracellular source of phosphoenolpyruvate. When the cells had been induced to high levels of the phosphoglycerate transport system, a low extracellular concentration of phosphoenolpyruvate (0.1 mM) half maximally stimulated uptake of methyl alpha-glucoside via the phosphoenolpyruvate:sugar phosphotransferase system. If the phosphoglycerate transport system was not induced before energy depletion, 100 times this concentration of phosphoenolpyruvate was required for half-maximal stimulation. Phosphoenolpyruvate could not be replaced by other energy sources if potassium fluoride (an inhibitor of enolase) was present. Inhibition of [14C]-glycerol uptake into energy-depleted cells by methyl alpha-glucoside was demonstrated. A concentration of phosphoenolpyruvate which stimulated methyl alpha-glucoside accumulation counteracted the inhibitory effect of the glucoside. In the presence of potassium fluoride, phosphoenolpyruvate could not be replaced by other energy sources. Inhibition of glycerol uptake by methyl alpha-glucoside in intact untreated cells was also counteracted by phosphoenolpyruvate, but several energy sources were equally effective; potassium fluoride was without effect. These and other results were interpreted in terms of a mechanism in which the relative proportions of the phosphorylated and nonphosphorylated forms of a cell constituent influence the activity of the glycerol transport system.
Metabolite gene regulation: imidazole and imidazole derivatives which circumvent cyclic adenosine 3',5'-monophosphate in induction of the Escherichia coli L-arabinose operon
Authors: Kline E L , Bankaitis V A , Brown C S , Montefiori D C
Published: January 2020

Imidazole, histidine, histamine, histidinol phosphate, urocanic acid, or imidazolepropionic acid were shown to induce the L-arabinose operon in the absence of cyclic adenosine 3',5'-monophosphate. Induction was quantitated by measuring the increased differential rate of synthesis of L-arabinose isomerase in Escherichia coli strains which carried a deletion of the adenyl cyclase gene. The crp gene product (cyclic adenosine 3',5'-monophosphate receptor protein) and the araC gene product (P2) were essential for induction of the L-arabinose operon by imidazole and its derivatives. These compounds were unable to circumvent the cyclic adenosine 3',5'-monophosphate in the induction of the lactose or the maltose operons. The L-arabinose regulon was catabolite repressed upon the addition of glucose to a strain carrying an adenyl cyclase deletion growing in the presence of L-arabinose with imidazole. These results demonstrated that several imidazole derivatives may be involved in metabolite gene regulation (23).
Localization of bacteriophage receptor, clumping factor, and protein A on the cell surface of Staphylococcus aureus
Authors: Umeda A , Ikebuchi T , Amako K
Published: January 2020

The surface of several laboratory strains of Staphylococcus aureus were observed with a scanning electron microscope, and the presence of two morphologically characteristic structures--a ridge separating cell surface into old and new surfaces and a concentric circular structure--are described. These two structures seemed to be present universally on the surfaces of cells of the genus Staphylococcus. The removal of the circular structures by a mild treatment of the cell with trichloroacetic acid suggested that this structure seemed to represent circularly arranged teichoic acid. With experiments using morphologically recognizable markers among three of the cell wall components, clumping factor, phage receptor, and protein A, the clumping factor was proven to be specifically localized on the old surface; and more phage receptors were detected on the old surface than on the new surface, but protein A was present all over the cell surface. This indicated that the clumping factor and most of the phage receptors appeared on the cell wall surface in a late stage of the cell growth cycle, but protein A was present in an early stage of the growth. The idea of aging of the cell wall is discussed.