bluuebunny/crossref_metadata_2025 huggingface dataset:
Glucose-triggered germination of Bacillus megaterium spores
Authors: Racine F M , Dills S S , Vary J C
Published: January 2020

Triggering of germination in Bacillus megaterium QM B1551 spores with D-glucose was studied. First, the interaction of glucose with spores for less than 1 min resulted in triggering almost 90% of the spores after the glucose was removed by dilution. Therefore only a brief time is needed for glucose to trigger germination, and then the continuous presence of glucose is not necessary. Detectable uptake of glucose began 2 to 3 min after absorbance loss started, and a non-metabolizable glucose analog, methyl-alpha-D-glucopyranoside, triggered germination in the absence of detectable uptake. Several inhibitors that reduced or eliminated glucose uptake did not block triggering of germination. Therefore, glucose uptake may be a relatively late event and not a prerequisite for triggering of germination.
Light Effects in Yeast: Evidence for Participation of Cytochromes in Photoinhibition of Growth and Transport in
Saccharomyces cerevisiae
Cultured at Low Temperatures
Authors: Ułaszewski Stanislaw , Mamouneas Theofanis , Shen Win-Kuang , Rosenthal Philip J. , Woodward John R. , Cirillo Vincent P. , Edmunds Leland N.
Published: January 2020

Visible light of moderate intensity inhibits growth, respiration, protein synthesis, and membrane transport in bakers' yeast and has a deleterious effect on membrane integrity. The results of this study indicate that these effects require the presence of cytochromes
b
and
a/a
3
. The light sensitivities of growth rate and [
14
C]histidine uptake in wild-type
rho
+
Y185 and D225-5A strains of
Saccharomyces cerevisiae
were compared with those in a variety of mutants lacking cytochrome
b
or
a/a
3
or both; a close correlation was found between the presence of these respiratory pigments and photosensitivity. Thus, strain TL5-3C, a nuclear petite lacking cytochromes
b, a
, and
a
3
, was resistant to light; strain GL5-6A, another nuclear petite having reduced amounts of cytochromes
a
and
a
3
, was partially resistant; strains MB127-20C and MB1-6C, nuclear petites lacking only cytochrome
b
, were also only partially resistant to light; whereas mutants containing all three cytochromes but having their respiratory chain either nonfunctional (strain ZK3-6B) or uncoupled (strain 18-27/t12) were fully sensitive to light. Finally, an equal-energy, broad-band action spectrum for the light inhibition of growth and transport indicated that blue light (408 nm) was most effective; these wavelengths correspond to the Soret region of the cytochrome absorption spectrum. The results suggest, therefore, that the yeast cytochromes
b, a
, and
a
3
are the primary photoreceptors for the inhibitory effects of light and, perhaps, for other processes, such as the entrainment of biological rhythms in this species.
Morphological stabilization of capsules of group B streptococci, types Ia, Ib, II, and III, with specific antibody
Authors: Mackie E B , Brown K N , Lam J , Costerton J W
Published: January 2020

Antibody prepared to the type-specific capsular polysaccharides of group B streptococci was used to demonstrate a stabilizing effect on the capsular glycocalyx. This permitted visualization by electron microscopy of the size of the capsule relative to the rest of the bacterial cell, and clear differences in the dimensions of untreated and antibody-treated capsular material were noted. Antibodies produced against group B streptococci types Ia, Ib, II, and III were used to demonstrate morphologically that the organization and extent of the capsular glycocalyx more closely resembles its natural state on stabilization by reaction with specific antibody.
Sensitivity of Escherichia coli to cephaloridine at different growth rates
Authors: Mathys E , Van Gool A
Published: January 2020

Steady-state populations of Escherichia coli B/r were treated with cephaloridine at minimal inhibitory concentrations. The antibiotic sensitivity of the cells and the localization of spheroplast emergence along the cell surface were examined as a function of cell length and growth rate. In fast-growing populations (greater than 1 division per h) the sites of cephaloridine interaction occurred preferentially at the cell pole in the smaller cells and at the cell center in dividing cells. At decreasing growth rates the cells became more resistant to cephaloridine, and a gradual shift from the cell pole toward the cell center was observed for the sphere position. A similar growth rate-dependent change in localization was found for sucrose-induced plasmolysis vacuoles.
Presence of a major (storage?) protein in dormant spores of the fungus Botryodiplodia theobromae
Authors: Van Etten J L , Freer S N , McCune B K
Published: January 2020

Approximately 23% of the protein isolated from dormant spores of Botryodiplodia theobromae consisted of a single polypeptide; the polypeptide is probably degraded during germination.
Light-induced, carrier-mediated transport of tetracycline by Rhodopseudomonas sphaeroides
Authors: Weckesser J , Magnuson J A
Published: January 2020

Tetracycline accumulation by the phototrophic bacterium Rhodopseudomonas sphaeroides has been studied, using the fluorescence properties of the antibiotic and measuring uptake of [7- 3H]tetracycline. Accumulation was carrier mediated, with a Km of approximately 300 micronM. Efflux also appeared to be carried mediated, with a Km of 25 mM. Chlorotetracycline competitively inhibited tetracycline transport. The transport was energy dependent. Efflux occurred during the influx process, and an energy-requiring steady state was reached when influx balanced efflux. Transport was inhibited by metabolic inhibitors such as antimycin A, cyanide, and iodoacetate. Proton conductors such as carbonylcyanide m-chlorophenyl hydrazone were strongly inhibitory. Efflux was not energy dependent. Efflux is partially blocked by mercuric ions and completely blocked by an external pH of 9 to 11. Although efflux rates increased continuously with lowering of the pH, influx rates have a sharp maximum at pH 7.
Organization of structural and regulatory genes that mediate tetracycline resistance in transposon Tn10
Authors: Jorgensen R A , Reznikoff W S
Published: January 2020

The location of Tn10 genes encoding tetracycline resistance and its regulation was determined by analyzing the properties of recombinant plasmids carrying partial HpaI digestion products of lambda::Tn10 transducing phage deoxyribonucleic acid. Within a 2,700-base pair region are encoded tetracycline resistance, the structural gene (tet) for a tetracycline-inducible polypeptide, and the regulatory elements for the induction of both the resistance phenotype and the polypeptide. Fusion of different sequences to an HpaI site in the tet gene alters the molecular weight and stability of the polypeptide as well as the tetracycline resistance phenotype of strains producing fusion polypeptides. These results indicate the orientation of the tet gene and support the conclusion that the tet polypeptie is required for tetracycline resistance. A HincII cleavage site immediately upstream from the tet gene is protected by ribonucleic acid polymerase, but only the absence of ribonucleotide triphosphates. The possibility that tet transcription is initiated at this site is discussed.
Biosynthesis of phenazine pigments in mutant and wild-type cultures of Pseudomonas aeruginosa
Authors: Byng G S , Eustice D C , Jensen R A
Published: January 2020

Pigmentation mutants of Pseudomonas aeruginosa, selected by observed visual differences in coloration from the wild-type strain, were examined for altered patterns of phenazine synthesis. Three classes of mutants that were incapable of pyocyanine production were identified. Pigmentation patterns that were found to characterize the various mutant classes implicated precursor-product relationships, and a biochemical scheme covering the terminal reactions of pyocyanine biosynthesis is proposed. Among compounds tested as inhibitors of pigmentation, two effectively inhibited pyocyanine production production while allowing cell growth. p-Aminobenzoate inhibited total pigmentation; i.e., no other phenazine accumulated. m-Aminobenzoate inhibited a presumptive methylation step in pyocyanine biosynthesis, abolishing the formation of pyocyanine and aeruginosin pigments but increasing the yields of phenazine 1-carboxylic acid and oxychlororaphin. D-[2,3,4,5(n)-14C]shikimate was most efficiently incorporated into phenazines in the middle to late exponential phase of growth. Label was incorporated predominantly into pyocyanine in the absence of inhibitors and into phenazine 1-carboxylic acid when the organism was grown in the presence of m-aminobenzoate.
Phosphate-limited continuous culture of Rhodotorula rubra: kinetics of transport, leakage, and growth
Authors: Robertson B R , Button D K
Published: January 2020

The phosphate-limited growth kinetics of Rhodotorula rubra, a small yeast of marine origin, were examined by analysis of 32P distributions in continuous cultures. Isotope relaxation procedures were used to identify unidirectional flows of Pi and organic phosphate among compartments modeled during growth. The concentrations of phosphates in these compartments at various growth rates were used, together with attendant flows, to produce a mathematical model of growth. Both Pi and phosphate-containing metabolic intermediates leaked from cells during growth. Total leakage ranged from 4 to 10% of influx and was comprised mostly of Pi. Transport capacity was at least 10 times that required for growth at saturating Pi concentrations, so that influx was linear with concentration during growth. This led to the realization that the curvature of Monod plots (Kmu = 12 nM mumax = 0.18/h, and the threshold At = 2.5 nM) is due to change in yield with growth rate. Growth rate related to Pi by the affinity, aA (= 0.43 liter/mg of cells.h) of cells for Pi and the growth rate-dependent yield. It was also specified by a series of kinetic constants that specified flow among the various compartments and equilibrium compartment concentrations as they were set by extracellular Pi. The importance of leakage by healthy cells to the organic chemistry of aquatic systems is noted.
In vivo regulation of chromosomal beta-lactamase in Escherichia coli
Authors: Jaurin B , Normark S
Published: January 2020

Chromosomal beta-lactamase, a periplasmic enzyme of Escherichia coli, was studied with respect to its regulation in vivo. Both the activity and the amount of beta-lactamase increased with growth rate. During a nutritional shift-down, chromosomal beta-lactamase activity followed stable ribonucleic acid accumulation. After a nutritional shift-up the differential rate of beta-lactamase synthesis did not increase immediately (like stable ribonucleic acid), but did increase after a lag period of 30 min. To determine whether beta-lactamase was under stringent control, strains carrying a temperature-sensitive valyl-transfer ribonucleic acid synthetase and differing only in the allelic state of the relA gene were shifted from a permissive to a semipermissive temperature. No influence by the relA gene product was found on beta-lactamase synthesis. The regulation of this periplasmic enzyme is discussed in relation to that of some components of the translational apparatus.
Structure of common pili from Escherichia coli
Authors: McMichael J C , Ou J T
Published: January 2020

Several important properties of the common pili from Escherichia coli are discussed. These pili were resistant to the gentle Folin-Ciocalteau reagent methods for protein detection and were not readily solubilized by sodium dodecyl sulfate. They were found to contain a reducing sugar but not peptidoglycan. The pilin had multiple conformations in sodium dodecyl sulfate solution, and the appearance of multiple bands on sodium dodecyl sulfate gels did not necessarily indicate heterogeneity of the preparation. The ilus subunit was found to be a different protein than outer membrane III, which has the same apparent molecular weight. In addition, we conformed the results of Brinton (Trans. N.Y. Acad. Sci 27:1003-1054, 1965): that there is a dramatic change in the properties of pili after they are heated at pH values below 2.
Deoxyribonucleic acid sequence common to staphylococcal and streptococcal plasmids which specify erythromycin resistance
Authors: Weisblum B , Holder S B , Halling S M
Published: January 2020

Plasmids from erythromycin-resistant Staphylococcus aureus, Streptococcus sanguis, and Streptococcus faecalis show deoxyribonucleic acid sequence homology. The homologous sequences can be localized to specific restriction endonuclease fragments, which in the case of S. aureus plasmid pI258 involves a single fragment from either EcoRI or HindIII digest known to contain the erythromycin resistance determinant. Complementary ribonucleic acid probes prepared from S. aureus plasmid pI258 and S. sanguis plasmid pAM77 also hybridize to specific fragments in restriction endonuclease digests of deoxyribonucleic acid from erythromycin-resistant Streptococcus progenes and Streptococcus pneumoniae. These studies suggest a common origin for a class of erythromycin resistance determinants in unrelated strains of pathogenic bacteria for which exchange of genetic material has not been demonstrated.
Physiological Effects of Seven Different Blocks in Glycolysis inSaccharomyces cerevisiae
Authors: Ciriacy Michael , Breitenbach Ingrid
Published: January 2020

Saccharomyces cerevisiaemutants unable to grow and ferment glucose have been isolated. Of 45 clones isolated, 25 had single enzyme defects of one of the following activities: phosphoglucose isomerase (pgi), phosphofructokinase (pfk), triosephosphate isomerase (tpi), phosphoglycerate kinase (pgk), phosphoglyceromutase (pgm), and pyruvate kinase (pyk). Phosphofructokinase activities in crude extracts of thepfkmutant were only 2% of the wild-type level. However, normal growth on glucose medium and normal fermentation of glucose suggested either that the mutant enzyme was considerably more active in vivo or, alternatively, that 2% residual activity was sufficient for normal glycolysis. All other mutants were moderately to strongly inhibited by glucose. Unusually high concentrations of glycolytic metabolites were observed before the reaction catalyzed by the enzyme which was absent in a given mutant strain when incubated on glucose. This confirmed at the cellular level the location of the defect as determined by enzyme assays. Withadh(lacks all three alcohol dehydrogenase isozymes) andpgkmutants, accumulation of the typical levels of hexosephosphates was prevented when respiration was blocked with antimycin A. A typical feature of all glycolytic mutants described here was the rapid depletion of the intracellular adenosine 5′-triphosphate pool after transfer to glucose medium. No correlation of low or high levels of fructose-1,6-bisphosphate with the degree of catabolite repression and inactivation could be found. This observation does not support the concept that hexose metabolites are directly involved in these regulatory mechanisms in yeast.
Auxotrophic Mutants of
Cryptococcus neoformans
Authors: Jacobson Eric S. , Ayers Deborah J.
Published: January 2020

Auxotrophic mutants of
Cryptococcus neoformans
have been obtained by using the methods of mutagenesis and replica-plating.
Novel acriflavin resistance genes, acrC and acrD, in Escherichia coli K-12
Authors: Nakamura H
Published: January 2020

Acriflavine-resistant mutants were isolated from an acriflavine-sensitive (acrA) strain of Escherichia coli K-12 and then tested for temperature sensitivity of cell division. Genetic analysis characterized two new genetic loci, acrC and acrD. The former was mapped between tonA and proA, and the latter between the origin of genetic transfer of HfrH and serB. acrC and acrD mutants could divide but did not initiate a new round of deoxyribonucleic acid (DNA) replication at 43 degrees C. DNA synthesis of the acrC mutant cells ceased after a period of time following temperature shift-up, and thereafter DNA degradation occurred. However, cell mass continued to increase for a long time at the nonpermissive temperature. On the other hand, DNA synthesis of the acrD mutant cells ceased soon after the shift-up, and the cell mass did not appreciably increase during the prolonged incubation.
Distribution of the phosphoenolpyruvate:glucose phosphotransferase system in fermentative bacteria
Authors: Romano A H , Trifone J D , Brustolon M
Published: January 2020

A number of selected fermentative bacteria were surveyed for the presence of the phosphoenolpyruvate:glucose phosphotransferase system, with particular attention to those organisms which ferment glucose by pathways other than the Embden-Meyerhof-Parnas pathway. The phosphoenolpyruvate:glusoe phosphotransferase system was found in all homofermentative lactic acid bacteria tested that ferment glucose via the Embden-Meyerhof-Parnas pathway, but in none of a group of heterofermentative species of Lactobacillus or Leuconostoc, which ferment glucose via the phosphoketolase pathway. A phosphoenolpyruvate:glucose phosphotransferase system was also absent in Zymomonas mobilis, which ferments glucose via an anaerobic Entner-Doudoroff pathway. It thus appears that the phosphotransferase mode of glucose transport is limited to bacteria with the Embden-Meyerhof-Parnas mode of glucose fermentation.
Decreased binding of polymyxin by polymyxin-resistant mutants of Salmonella typhimurium
Authors: Vaara M , Vaara T , Sarvas M
Published: January 2020

Polymyxin-resistant pmrA strains were shown to absorb only about 25% of the amount of polymyxin absorbed by the corresponding polymyxin-sensitive parent strains. The lipopolysaccharide from the pmrA strains bound less polymyxin than the lipopolysaccharide from the parent strains.
Haemophilus influenzae periplasmic protein which binds deoxyribonucleic acid: properties and possible participation in genetic transformation
Authors: Sutrina S L , Scocca J J
Published: January 2020

A protein which binds to either single-stranded or double-stranded deoxyribonucleic acid (DNA) but not to ribonucleic acid has been isolated by osmotic shock treatment of growing cells. This periplasmic protein differs from the principal intracellular binding protein in its greater thermolability and by the absence of salt-induced cooperativity in its interaction with single-stranded DNA. Certain mutant strains of Haemophilus influenzae defective in the DNA suptake steps of genetic transformation were found to be deficient in periplasmic DNA-binding protein, suggesting that this protein participates in the uptake of DNA in transformation.
Circadian Rhythms in
Neurospora crassa
: Effects of Saturated Fatty Acids
Authors: Mattern Daniell , Brody Stuart
Published: January 2020

To assess their effects on the conidiation rhythm in
Neurospora
, 14 saturated fatty acids from 6 to 24 carbons long were used to supplement the
bd csp
and
bd csp cel
strains. Both strains express a circadian spore-forming rhythm when grown on solid media; the
cel
mutation confers a partial fatty acid requirement. Fatty acid supplements from 8 to 13 carbons long lengthened the free-running period of
bd csp cel
compared with the control value of 21 h; the maximal effect (33 h) was obtained with nonanoic acid (9:0) at a concentration of 5 × 10
−4
M. In contrast, the period of
bd csp
remained unchanged under all experimental conditions. The short-chain fatty acids (<14 carbons) reduced the rate of advance of the growth front in both strains, compared with unsupplemented controls. However, this inhibition did not appear to be responsible for the lengthened periods in
bd csp cel
. Nor was direct incorporation of the short-chain (period-lengthening) fatty acids into mycelial total lipids responsible, since such incorporation was not observed. In fact, extensive metabolic conversion of these supplements by both strains was indicated by the disappearance of short-chain fatty acids from the agar media coupled with their absence in mycelial lipids, and by the liberation of
14
CO
2
from cultures supplemented with [1-
14
C]lauric acid (12:0).
Spore lytic enzyme released from Clostridium perfringens spores during germination
Authors: Ando Y
Published: January 2020

The exudate of fully germinated spores of Clostridium perfringens was found to contain a large amount of a spore lytic enzyme which acted directly on alkali-treated spores of the organism to cause germination. Although no detectable amount of the enzyme was found in dormant spores during germination in a KCl medium, the enzyme was produced rapidly and released into the medium. The optimal conditions for enzyme activity were pH 6.0 and 45 degrees C. Maximum activity occurred in the presence of various univalent cations at a concentration of 50 mM. The enzyme was readily inactivated by several sulfhydryl reagents. A strong reducing condition was generated in the ionic germination of the spores, a minimum Eh level of -350 mV being reached 30 min after initiation of germination. Furthermore, adenosine triphosphate-dependent pyruvate:ferredoxin oxidoreductase (EC 1.2.7.1) was identified in both dorman and germinated spores. The relationship between the release of active enzyme and the generation of reducing conditions during germination is discussed.
Rhamnose-induced propanediol oxidoreductase in Escherichia coli: purification, properties, and comparison with the fucose-induced enzyme
Authors: Boronat A , Aguilar J
Published: January 2020

Escherichia coli are capable of growing anaerobically on L-rhamnose as a sole source of carbon and energy and without any exogenous hydrogen acceptor. When grown under such condition, synthesis of a nicotinamide adenine dinucleotide-linked L-lactaldehydepropanediol oxidoreductase is induced. The functioning of this enzyme results in the regeneration of nicotinamide adenine dinucleotide. The enzyme was purified to electrophoretic homogeneity. It has a molecular weight of 76,000, with two subunits that are indistinguishable by electrophoretic mobility. The enzyme reduces L-lactaldehyde to L-1,2-propanediol with reduced nicotinamide adenine dinucleotide as a cofactor. The Km were 0.035 mM L-lactaldehyde and 1.25 mM L-1,2-propanediol, at pH 7.0 and 9.5, respectively. The enzyme acts only on the L-isomers. Strong substrate inhibition was observed with L-1,2-propanediol (above 25 mM) in the dehydrogenase reaction. The enzyme has a pH optimum of 6.5 for the reduction of L-lactaldehyde and of 9.5 for the dehydrogenation of L-1,2-propanediol. The enzyme is, according to the parameters presented in this report, indistinguishable from the propanediol oxidoreductase induced by anaerobic growth on fucose.
Genetics and physiology of proline utilization in Saccharomyces cerevisiae: enzyme induction by proline
Authors: Brandriss M C , Magasanik B
Published: January 2020

Proline is converted to glutamate in the yeast Saccharomyces cerevisiae by the sequential action of two enzymes, proline oxidase and delta 1-pyrroline-5-carboxylate (P5C) dehydrogenase. The levels of these enzymes appear to be controlled by the amount of proline in the cell. The capacity to transport proline is greatest when the cell is grown on poor nitrogen sources, such as proline or urea. Mutants have been isolated which can no longer utilize proline as the sole source of nitrogen. Mutants in put1 are deficient in proline oxidase, and those in put2 lack P5C dehydrogenase. The put1 and put2 mutations are recessive, segregate 2:2 in tetrads, and appear to be unlinked to one another. Proline induces both proline oxidase and P5C dehydrogenase. The arginine-degradative pathway intersects the proline-degradative pathway at P5C. The P5C formed from the breakdown of arginine or ornithine can induce both proline-degradative enzymes by virtue of its conversion to proline.
Glutamine synthetase mutations which affect expression of nitrogen fixation genes in Klebsiella pneumoniae
Authors: Ausubel F M , Bird S C , Durbin K J , Janssen K A , Margolskee R F , Peskin A P
Published: January 2020

Previous studies have implicated glutamine synthetase (L-glutamate:ammonia ligase [adenosine diphosphate for-ing], EC 6.6.1.2) as a major controlling element of the nitrogen fixation (nif) genes in Klebsiella pneumoniae. We report here the isolation of a new class of K. pneumoniae mutants which exhibit altered patterns of nif and hut (histidine utlization) regulation. The expression of nif in these mutants, which were isolated as Gln+ (glutamine nonrequiring) revertants of a particular glnA mutation, is extremely sensitive to ammonia repression. These mutants have a Nif- Hut- phenotype at external ammonia concentrations at which wild-type strains are Nif+ Hut+. On the other hand, these mutants can be fully derepressed for nif at very low ammonia concentrations. We adopted the nomenclature "GlnR- (Nif- Hut-)" to facilitate discussion of the phenotype of these mutant strains. The mutations in these strains which confer the GlnR- phenotype map at or near glnA, the structural gene for glutamine synthetase.
Regulatory nucleotides involved in the Rel function of Bacillus subtilis
Authors: Nishino T , Gallant J , Shalit P , Palmer L , Wehr T
Published: January 2020

We have examined the accumulation of polyphosphorylated nucleotides in Bacillus subtilis in relation to the function of the rel gene. Our results are as follows. (i) During inhibition of isoleucine activation by O-methylthreonine, wildtype B. subtilis cells accumulate unusual nucleotides with the chromatographic and chemical properties of pppApp, ppApp, pppGpp, ppGpp, pGpp, and ppGp. (ii) During the carbon source downshift elicited by inhibiting glucose uptake, we observed accumulation of the polyphosphorylated guanosine but not adenosine nucleotides. (iii) At the end of long phase in sporulation medium, we observed a small transient accumulation of the polyphosphorylated guanosine but not adenosine nucleotides. (iv) We were unable to detect a nucleotide with chromatographic behavior expected for pppAppp under any conditions. (v) The rel mutant of Swanton and Edlin (Biochem. Biophys. Res. Commun. 46-583-588, 1972) did not accumulate any of these polyphosphorylated nucleotides under any of the conditions examined. (vi) the rel mutant is unimpaired in sporulation. We conclude that one or more of the nucleotides we have detected may be involved in controlling the specificity of transcription during the stringent response, but none of them are required for sporogenesis.
Isolation and pure culture of a freshwater magnetic spirillum in chemically defined medium
Authors: Blakemore R P , Maratea D , Wolfe R S
Published: January 2020

A bipolarly flagellated magnetotactic spirillum containing intracellular chains of single domain-sized magnetite crystals was isolated by applying a magnetic field to sediments from a freshwater swamp. The organism was cultured in a chemically defined medium containing ferric quinate and succinate as sources of iron and carbon, respectively. Nonmagnetic variants of this isolate were maintained in chemically defined medium lacking ferric quinate. In contrast to magnetic cells, these had less iron and lacked measurable magnetic remanence and the intracytoplasmic crystals. In other respects, including moles percent guanine plus cytosine content, growth characteristics, nutrition, and physiology, the two types were similar. The isolate reduced nitrate without accumulating nitrite and produced ammonia during growth. Nitrate or ammonium ions served as a nitrogen source. The organism was microaerophilic and did not grow anaerobically with nitrate in the medium. In chemically defined medium, cells synthesized magnetite only if the initial O2 concentration in the atmosphere of sealed cultures was 6% (vol/vol) or less.
Modulation of Protein A Formation in
Staphylococcus aureus
by Genetic Determinants for Methicillin Resistance
Authors: Cohen Sidney , Sweeney Helen M.
Published: January 2020

Many methicillin-resistant (Mec
r
) strains of
Staphylococcus aureus
either produce no protein A or secrete it extracellularly (S. Winblad and C. Ericson, Acta Pathol. Microbiol. Scand. Sect. B
81:
150–156, 1973). We found that methicillin resistance and protein A production were apparently lost coordinately from the natively Mec
r
strain A676. Restoration of the genetic determinant for methicillin resistance (
mec
) by transduction or transformation restored protein A production. In two other Mec
r
strains, loss of
mec
was accompanied by marked reduction in protein A formation. Genetic transfer of
mec
to derivatives of
S. aureus
8325 affected protein A formation differently with different
mec
determinants. Those derived from strain A676 and two other Mec
r
strains reduced the scanty amount of protein A produced by strain 8325 to even lower or undetectable levels, whereas
mec
from two more Mec
r
strains increased its protein A content. This “
mec
-effect,” i.e., stimulation or inhibition of protein A formation dependent on the combination of host strain and
mec
determinant, was reduced in methicillin-susceptible (Mec
s
) mutants produced by ethyl methane sulfonate treatment of Mec
r
strains. The
mec
-effect reappeared in spontaneous revertants to methicillin resistance. Phenotypic reduction of methicillin resistance in Mec
r
strains grown at 44°C was accompanied by reduction of the
mec
-effect on protein A, but it had no effect on protein A formation in Mec
s
strains. Two independent mutants of strain 8325 produced large amounts of protein A at rates that were unaffected by growth at 44°C or by the introduction of
mec
determinants.
Interaction of bacteriophage T4 with reconstituted cell envelopes of Escherichia coli K-12
Authors: Furukawa H , Yamada H , Mizushima S
Published: January 2020

The interaction with bacteriophage T4 of the cell surface of Escherichia coli K-12 reconstituted from outer membrane protein O-8, lipopolysaccharide, and the lipoprotein-bearing peptidoglycan sacculus was studied. The reconstituted cell surface was active as a receptor for the phage, resulting in the contraction of the tail sheath, a morphological change in the base plate which was accompanied by the extension of short tail pins down to the cell surface and the penetration of the needle through the cell surface. However, the ejection of phage deoxyribonucleic acid did not take place. Both O-8 and lipopolysaccharide were essential for the interaction. In the reconstitution, the wild-type lipopolysaccharide could not be replaced by either heptoseless lipopolysaccharide or lipid A. The lipoprotein-bearing peptidoglycan sacculus was also found to be an active component for the phage adsorption. The sacculus most likely functioned as a basal framework on which O-8 and lipopolysaccharide assembled to form a flat sheet which is large enough to interact with individual distal ends of long tail fibers of a single phage particle.
Hyaluronic acid capsule: strategy for oxygen resistance in group A streptococci
Authors: Cleary P P , Larkin A
Published: January 2020

Unencapsulated variants of encapsulated, M-protein-positive group A streptococci are oxygen sensitive and secrete inhibitory concentrations of hydrogen peroxide when grown in aerated broth cultures. The organisms were equally sensitive to hydrogen peroxide, and neither exhibited catalase or peroxidase activity, suggesting that differences in oxygen sensitivity reflect dissimilarity in oxygen uptake. The encapsulated parental culture was found to grow in aggregates that take up oxygen more slowly than unencapsulated, oxygen-sensitive derivatives. Moreover, the latter grow in an unaggregated, homogenous suspension. The enzyme hyaluronidase was able to disrupt aggregates of the encapsulated strain increase the rate that these cells take up oxygen, and cause the accumulation of toxic concentrations of hydrogen peroxide earlier in their growth cycle. The evidence presented shows that the aggregation of streptococcal cells by their hyaluronic acid capsule provides this organism with a novel means to avoid self-destruction by oxygen metabolites--cells are shielded from oxygen. The reduced surface-to-volume ratio and limited diffusion of oxygen into the interior of aggregates are proposed as the protective mechanism.
Dielectric properties of native and decoated spores of Bacillus megaterium
Authors: Carstensen E L , Marquis R E , Child S Z , Bender G R
Published: January 2020

A general model for use in interpreting dielectric data obtained with bacterial endospores is developed and applied to past results for Bacillus cereus spores and new results for Bacillus megaterium spores. The latter were also subjected to a decoating treatment to yield dormant cells with damaged outer membranes that could be germinated with lysozyme. For both spore types, core ions appeared to be completely immobilized, and decoating of B. megaterium spores did not affect this extreme state of electrostasis in the core. The cortex of B. megaterium appeared to contain a high level of mobile ions, in the cortex of B. cereus. The outer membrane-coat complex of B. megaterium acted dielectrically as an insulating layer around the cortex, so that native dormant spores showed a Maxwell-Wagner dispersion over the frequency range from about 1 to 20 MHz. The decoating treatment resulted in a shift in the dispersion to frequencies below the range of observation. Increases in cell conductivity in response to increases in environmental ionic strength indicated that the coats. of B. megaterium could be penetrated by environmental ions and that they had an inherent fixed charge concentration of about 10 to 20 milliequivalents per liter. In contrast, the dispersion for B. cereus spores was very sensitive to changes in environmental ion concentration, and it appeared that some 40% of the spore volume could be penetrated by environmental ions and that these ions traversed a dielectrically effective layer, either the exosporium or the outer membrane. It appears that dormancy is associated with extreme electrostasis of core ions but not necessarily of ions in enveloping structures and that the coat-outer membrane complex is dielectrically effective but not required for maintenance of extreme electrostasis in the core.
Carotenoids acts as reinforcers of the Acholeplasma laidlawii lipid bilayer
Authors: Rottem S , Markowitz O
Published: January 2020

Acholeplasma laidlawii cells grown with oleic acid produced much more colored carotenoids than did cells grown with elaidic acid. The amount of carotenoids was decreased 80 to 90% by growing the cells with 0.05 M propionate, resulting in a marked increase in the mobility of both 5-doxylstearate and 12-doxylstearate incorporated into the membranes. The fatty acid composition of the propionate-grown cells differed from that of cells grown without propionate by containing odd-numbered rather than even-numbered saturated fatty acids, but the ratios of saturated to unsaturated fatty acids were the same. To determine whether the carotenoids are the cause for the restricted mobility in the membranes, the carotenoids were selectively removed from A. laidlawii membranes by incubating the membranes with phosphatidylcholine vesicles. The carotenoid-depleted membranes showed an increase in the mobility of the hydrocarbon chains of the spin-labeled fatty acids. Furthermore, the incorporation of carotenoids into artificial membrane vesicles restricted the mobility of the hydrocarbon chain. Our results support the notion that the carotenoids in A. laidlawii act as a rigid insert reinforcing the membrane bilayer.
Control of Plasmid R1 Replication: Functions Involved in Replication, Copy Number Control, Incompatibility, and Switch-off of Replication
Authors: Molin Søren , Nordström Kurt
Published: January 2020

A small derivative of plasmid R1 was used to integratively suppress a chromosomaldnaA(Ts) mutation. The strain obtained grew normally at 42°C. The integratively suppressed strain was used as recipient for various plasmid R1 derivatives. Plasmid R1 and miniplasmid derivatives of R1 could be established in the strain that carried an integrated R1 replicon, but they were rapidly lost during growth. However, plasmids also carrying ColE1 replication functions were almost completely stably inherited. The integratively suppressed strain therefore allows the establishment of bacteria diploid with respect to plasmid R1 and forms a useful and sensitive system for studies of interaction between plasmid R1 replication functions. Several of the chimeric plasmids caused inhibition of growth at high temperatures. All plasmids that inhibited growth carried one particularPstI fragment from plasmid R1 (thePstI F fragment), and in all cases the growth inhibition could be ascribed to repression of initiation of chromosome replication at 42°C, i.e., they carry atrans-acting switch-off function. Furthermore, the analogousPstI fragments from different copy mutants of plasmid R1 were analyzed similarly, and one mutant was found to lack the switch-off function. The different chimeric plasmids were also tested for their incompatibility properties. All plasmids that carried the switch-off function (and no other plasmids) also carried R1 incompatibility gene(s). Since thePstI F fragment, which is present on all these plasmids, is very small (0.35 × 106), it is suggested that the switch-off regulation of replication (by an inhibitor), incompatibility, and copy number control are governed by the same gene.
Characterization of chimeric plasmid cloning vehicles in Bacillus subtilis
Authors: Gryczan T , Shivakumar A G , Dubnau D
Published: January 2020

Restriction endonuclease cleavage maps of seven chimeric plasmids that may be used for molecular cloning in Bacillus subtilis are presented. These plasmids all carry multiple antibiotic resistance markers and were constructed by in vitro molecular cloning techniques. Several of the antibiotic resistance markers were shown to undergo insertional inactivation at specific restriction endonuclease sites. Kanamycin inactivation occurred at the BglII site of pUB110 derivatives, erythromycin inactivation occurred at the HpaI and BclI sites of pE194 derivatives, and streptomycin inactivation occurred at the HindIII site of pSA0501 derivatives. A stable mini-derivative of pBD12 was isolated and characterized. By using these plasmids, we identified proteins involved in plasmid-coded kanamycin and erythromycin resistance. The properties and uses of these chimeric plasmids in the further development of recombinant deoxyribonucleic acid technology in B. subtilis are discussed.
Properties of the Thiamine Transport System in
Escherichia coli
Authors: Yamada Kazuo , Kawasaki Takashi
Published: January 2020

Thiamine transport was studied with a mutant (KG1976) of
Escherichia coli
K-12 deficient in thiamine kinase (EC 2.7.1.89), which catalyzes the formation of thiamine monophosphate from thiamine. Mutant cells accumulated thiamine 390-fold as the free form against a concentration gradient in the absence of added carbon sources at the steady state. Thiamine taken up from the medium, or thiamine preloaded in the absence of glucose, was expelled into the medium when glucose,
d
-lactate, or succinate was added, whereas exit in the absence of glucose was very slow. The rate of thiamine entry was therefore determined in the absence of glucose, and that of thiamine exit was followed by the addition of glucose to thiamine-preloaded cells. The activities of thiamine entry and exit were optimal at 42 and 37°C, respectively. Hyperbolic saturation kinetics were obtained for the entry rate with a

K
m

value of 5.9 nM. The exit rate showed a sigmoidal dependence on cellular thiamine concentrations, and a half-maximal velocity was observed at 31 μM. The rates of both entry and exit were lowered by electron transport inhibitors and uncouplers, suggesting that the energy coupled to both processes was provided through substrate oxidation. Thiamine exit from K
+
-depleted cells was enhanced by K
+
alone and by Na
+
to a much lesser extent, and K
+
and glucose were found to be synergistic for thiamine exit. These cations had no effect on the entry of thiamine into KG1676 cells in the absence of glucose. These properties of the entry and exit of thiamine in KG1676 are discussed from the standpoint of the possible involvement of different membrane components or different sites of identical thiamine carrier protein.
Protonmotive force and bacterial sensing
Authors: Miller J B , Koshland D E
Published: January 2020

The role of the proton gradient and external pH in the motility and chemotaxis of Bacillus subtilis was investigated. Presence of a substantial proton gradient is not necessary for motility or chemotaxis, as long as the electrical potential is sufficient to maintain motility. Changes in the proton gradient do, however, lead to changes in swimming behavior, and these changes are mediated by two processes. One is sensitive to external pH and probably operates through a pH receptor. The second is sensitive to changes in the proton gradient. When the level of the protonmotive force is high enough to maintain motiligy, changes in the components of the protonmotive force are sensed by the bacteria and lead to behavioral changes, but changes in the protonmotive force are not necessary for chemotaxis.
Isolation and properties of calmodulin from Dictyostelium discoideum
Authors: Clarke M , Bazari W L , Kayman S C
Published: January 2020

A calcium-dependent regulatory protein (calmodulin) was purified from vegetative amoebae of Dictyostelium discoideum. The properties of Dictyostelium calmodulin are similar but not identical to those of bovine brain calmodulin. Calmodulin activity was not detected in extracts of Saccharomyces cerevisiae or Escherichia coli.
Effects of an insertion mutation in a locus affecting pyridine nucleotide transhydrogenase (pnt::Tn5) on the growth of Escherichia coli
Authors: Hanson R L , Rose C
Published: January 2020

The effects of a pnt::Tn5 insertion mutation on the growth of strains lacking phosphoglucoisomerase or glucose 6-phosphate dehydrogenase were examined. The results support the idea that the energy-linked transhydrogenase is an important source of reduced nicotinamide adenine dinucleotide phosphate for Escherichia coli under some conditions.
Cluster of mrdA and mrdB genes responsible for the rod shape and mecillinam sensitivity of Escherichia coli
Authors: Tamaki S , Matsuzawa H , Matsuhashi M
Published: January 2020

Two closely linked genes, mrdA and mrdB, located at ca. 14.2 min on the Escherichia coli chromosomal linkage map, seen to be responsible for the normal rod shape and mecillinam sensitivity of E. coli. The product of mrdA was concluded to be penicillin-binding protein 2, because mrdA mutations caused formation of thermosensitive penicillin-binding protein 2. The product of the mrdB gene is unknown. At 42 degrees, C, mutation in either of these genes caused formation of spherical cells and mecillinam resistance. Both mutations was recessive, and complementation, as detected in +-/-+ meroheterodiploids having the wild-type phenotype, provided strong evidence that the two mutations are in different complementation groups. P1 transduction suggested that the most plausible gene order is leuS-mrdA-mrdB-lip. The rodA mutation reported previously seems to be similar to the mrdB murations, but the identities of the two have not yet been proven.
Fine control of adenylate cyclase by the phosphoenolpyruvate:sugar phosphotransferase systems in Escherichia coli and Salmonella typhimurium
Authors: Feucht B U , Saier M H
Published: January 2020

Inhibition of cellular adenylate cyclase activity by sugar substrates of the phosphoenolpyruvate-dependent phosphotransferase system was reliant on the activities of the protein components of this enzyme system and on a gene designated crrA. In bacterial strains containing very low enzyme I activity, inhibition could be elicited by nanomolar concentrations of sugar. An antagonistic effect between methyl alpha-glucoside and phosphoenolpyruvate was observed in permeabilized Escherichia coli cells containing normal activities of the phosphotransferase system enzymes. In contrast, phosphoenolpyruvate could not overcome the inhibitory effect of this sugar in strains deficient for enzyme I or HPr. Although the in vivo sensitivity of adenylate cyclase to inhibition correlated with sensitivity of carbohydrate permease function to inhibition in most strains studied, a few mutant strains were isolated in which sensitivity of carbohydrate uptake to inhibition was lost and sensitivity of adenylate cyclase to regulation was retained. These results are consistent with the conclusions that adenylate cyclase and the carbohydrate permeases were regulated by a common mechanism involving phosphorylation of a cellular constituent by the phosphotransferase system, but that bacterial cells possess mechanisms for selectively uncoupling carbohydrate transport from regulation.
A rapidly metabolizing pool of phosphatidylglycerol as a precursor of phosphatidylethanolamine and diglyceride in Bacillus megaterium
Authors: Lombardi F J , Chen S L , Fulco A J
Published: January 2020

Pulse-chase experiments in Bacillus megaterium ATCC 14581 with [U-14C]palmitate, L-[U-14C]serine, and [U-14C]glycerol showed that a large pool of phosphatidylglycerol (PG) which exhibited rapid turnover in the phosphate moiety (PGt) underwent very rapid interconversion with the large diglyceride (DG) pool. Kinetics of DG labeling indicated that the fatty acyl and diacylated glycerol moieties of PGt were also utilized as precursors for net DG formation. The [U-14C]glycerol pulse-chase results also confirmed the presence of a second, metabolically stable pool of PG (PGs), which was deduced from [32P]phosphate studies. The other major phospholipid, phosphatidylethanolamine (PE), exhibited pronounced lags relative to PG and DG in 14C-fatty acid, [14C]glycerol, and [32P]phosphate incorporation, but not for incorporation of L-[U-14C]serine into the ethanolamine group of PE or into the serine moiety of the small phosphatidylserine (PS) pool. Furthermore, initial rates of L-[U-14C]serine incorporation into the serine and ethanolamine moieties of PS and PE were unaffected by cerulenin. The results provided compelling in vivo evidence that de novo PGt, PS, and PE synthesis in this organism proceed for the most part sequentially in the order PGt yields PS yields PE rather than via branching pathways from a common intermediate and that the phosphatidyl moiety in PS and PE is derived largely from the corresponding moiety in PGt, whereas the DG pool indirectly provides an additional source for this conversion by way of the facile PGt in equilibrium or formed from DG interconversion.
flu, a metastable gene controlling surface properties of Escherichia coli
Authors: Diderichsen B
Published: January 2020

flu, a gene of Escherichia coli K-12, was discovered and mapped between his and shiA. It is shown that flu is a metastable gene that changes frequently between the flu+ and flu states. flu+ variants give stable homogeneous suspensions, are piliated, and form glossy colonies. flu variants aggregate, fluff and sediment from suspensions, are nonpiliated, and form frizzy colonies. flu+ and flu variants can be isolated from most strains. Implications of these observations are discussed, and it is demonstrated that flu+ variants of strain P678-54 yield three times more minicells than flu variants.
Metabolism of naphthalene by pseudomonads: salicylaldehyde as the first possible inducer in the metabolic pathway
Authors: Connors M A , Barnsley E A
Published: January 2020

Pseudomonas ATCC 17483 produced enzymes for naphthalene metabolism when growing in a medium containing succinate and naphthalene. Mutants for naphthalene metabolism produced by treatment with N-methyl-N'-nitro-N-nitrosoguanidine were able to produce these enzymes only when the metabolic pathway was intact as far as salicylaldehyde, which was therefore identified as the first possible inducer.