bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasmids Controlling Synthesis of Hemolysin inEscherichia coli: Molecular Properties
Authors: Goebel Werner , Royer-Pokora Brigitte , Lindenmaier Werner , Bujard Hermann
Published: January 2020

Covalently closed extrachromosomal deoxyribonucleic acid (DNA) was isolated from alpha-hemolytic wild-type strains ofEscherichia coli. Most strains examined were able to transfer the hemolytic property with varying frequencies to nonhemolytic recipient strains. Out of eight naturally isolated alphahemolyticE. colistrains, four contained a set of three different supercoiled DNAs with sedimentation coefficients of 76S(plasmid A), 63S(plasmid B), and 55S(plasmid C). The sedimentation coefficients and the contour lengths of the isolated molecules correspond to molecular weights of 65 × 106, 41 × 106, and 32 × 106. Three alpha-hemolytic wild-type strains carried only one plasmid with a molecular weight of 41 × 106, and one strain harbored two plasmids with molecular weights of 41 × 106and 32 × 106. Alpha-hemolytic transconjugants were obtained by conjugation ofE. coliK-12 with the hemolytic wild-type strains. A detailed examination revealed that plasmids with the same sizes as plasmids B and C of the wild-type strains can be transferred separately or together to the recipients. Both plasmids possess the hemolytic determinant and transfer properties. Plasmid A appears to be, at least in one wild-type strain, an additional transfer factor without a hemolytic determinant. In one case a hemolytic factor was isolated, after conjugation, that is larger in size than plasmid A and appears to be a recombinant of both plasmids B and C.
Pyruvate Carboxylase Deficiency in Pleiotropic Carbohydrate-Negative Mutant Strains of
Pseudomonas aeruginosa
Authors: Phibbs P. V. , Feary T. W. , Blevins W. T.
Published: January 2020

Cell extracts of
Pseudomonas aeruginosa
strain PAO were found to contain pyruvate carboxylase activity. Specific activities were minimal when cells were grown on Casamino Acids, acetate, or succinate, but were three- to fourfold higher when cells were grown in glucose, gluconate, glycerol, lactate, or pyruvate minimal media. The reaction in crude cell extracts and in partially purified preparations was dependent on pyruvate, adenosine 5′-triphosphate, and Mg
2+
, but was not affected by either the presence or absence of acetyl coenzyme A. Activity was nearly totally inhibited by avidin and this inhibition was substantially blocked by free biotin in incubation mixtures. Cell extracts were shown to fix
14
CO
2
in a reaction that had these same characteristics. Eight pleiotropic, carbohydrate-negative mutant strains of the organism were isolated after nitrosoguanidine mutagenesis. Each mutant strain grew normally in acetate, succinate, and citrate minimal media but failed to utilize glucose, gluconate, 2-ketogluconate, mannitol, glycerol, lactate, and pyruvate as sole sources of carbon and energy. These strains were found by quantitative transductional analysis with phage F116 to form a single linkage group. Cell extracts of each mutant strain were either lacking or severely deficient in pyruvate carboxylase activity. Spontaneous revertants of five of the eight strains were isolated and found to recover simultaneously both pyruvate carboxylase activity and the ability to utilize each of the C
6
and C
3
compounds. A second linkage group of similar mutant strains that grew on the C
3
compounds was found to contain normal levels of pyruvate carboxylase activity, but each strain was deficient in an enzyme of the Entner-Doudoroff pathway.
d
-Arabitol Catabolic Pathway in
Klebsiella aerogenes
Authors: Charnetzky W. T. , Mortlock R. P.
Published: January 2020

Klebsiella aerogenes
strain W70 has an inducible pathway for the degradation of
d
-arabitol which is comparable to the one found in
Aerobacter aerogenes
strain PRL-R3. The pathway is also similar to the pathway of ribitol catabolism in that it is composed of a pentitol dehydrogenase,
d
-arabitol dehydrogenase (ADH), and a pentulokinase,
d
-xylulokinase (DXK). These two enzymes are coordinately controlled and induced in response to
d
-arabitol, the apparent inducer of synthesis of these enzymes. We obtained mutants which lacked a functional
d
-xylose pathway and were constitutive for the ribitol catabolic pathway. These mutants were able to grow on the unusual pentitol, xylitol, only if they contained the functional DXK of the
d
-arabitol pathway. This provided us with a specific selection technique for DXK
+
transductants. As in
A. aerogenes
, mutants constitutive for ADH were able to use this enzyme to convert the hexitol
d
-mannitol to
d
-fructose. With mutants blocked in the normal
d
-mannitol catabolic pathway, growth on
d
-mannitol became a test for ADH constitutivity. Growth of such mutants on xylitol,
d
-arabitol, and
d
-mannitol was utilized to classify transductants in mapping, by transductional analysis, the loci involved in
d
-arabitol utilization. Three-point crosses gave the order
dalK-dalD-dalC
, where
dalK
is the DXK structural gene,
dalD
is the ADH structural gene, and
dalC
is a regulatory site controlling synthesis of both enzymes.
Influence of Hydrocarbons and Derivatives on the Polar Lipid Fatty Acids of an
Acinetobacter
Isolate
Authors: Patrick Michael A. , Dugan Patrick R.
Published: January 2020

The effects of hydrocarbons and hydrocarbon derivatives as growth substrates on the polar lipid fractions of an
Acinetobacter
isolate were studied. Tetradecane, hexadecane, and octadecane resulted in the incorporation of substantial quantities of equivalent-chain-length fatty acids into cellular lipids. Cells cultured on nonane, the only odd-numbered alkane tested, contained both odd- and even-chain fatty acids. The
n
-alkane dotriacontane (32 carbons), 1-chlorohexadecane, 1-chlorododecane, 1-chlorodecane, and 1-phenyldodecane yielded significant amounts of odd-chain fatty acids. A subterminal oxidative pathway is believed to account for these results. Cells grown on long-chain alcohols exhibited fatty acid profiles nearly identical to those of cells grown on the corresponding alkanes.
Genetic Control of the Rate of α-Amylase Synthesis in
Bacillus subtilis
Authors: Yamaguchi Kazuo , Nagata Yoshiho , Maruo Bunji
Published: January 2020

The level of extracellular α-amylase (EC 3.2.1.1) of
Bacillus subtilis
Marburg was increased about fivefold by introducing the
amyR
marker from
B. natto
1212 through transformation.
amyR2
of
B. natto
1212 has been assumed to determine a high level of α-amylase of the organism. The gene acts specifically on α-amylase synthesis but not on the production of other extracellular enzymes. α-Amylase of an
amyR2
-carrying strain was found to be quite similar to that of an isogenic
amyR1
-carrying strain in the thermostability and electrophoretic behavior of whichever amylase the strain produces. Marburg-type α-amylase (
amyEm
) or
B. natto
-α-amylase (
amyEn
). Anti-amylase serum titration indicates that a high level of the enzyme activity in the
amyR2
-carrying strain is caused by the existence of more enzyme rather than the presence of an enzyme having higher efficiency. This is supported further by the fact that
amyR
controls the synthesis of the
amyE
gene product in mutant M9, which synthesizes a temperature-sensitive-α-amylase, and in mutant M07, which secretes cross-reacting material. The results indicate that
amyR
regulates the rate of α-amylase synthesis.
Isolation and Characterization of Mutants of Colicin Plasmids E1 and E2 After Mu Bacteriophage Infection
Authors: Inselburg Joseph
Published: January 2020

Cells colicinogenic for the colicin plasmids E1 or E2 (Col E1 and Col E2, respectively) were selected for a loss of colicin production after infection with bacteriophage Mu. Extrachromosomal deoxyribonucleic acid that was larger than the original colicin plasmids was found in such cells. A small insertion mutant in Col E1 deoxyribonucleic acid affecting active colicin production without affecting either expression of colicin immunity or Col E1 deoxyribonucleic acid replication was found. Cells carrying this Col E1 plasmid mutant do not exhibit the lethal event associated with colicin E1 induction, suggesting that synthesis of active colicin is required for killing during induction. The altered Col E2 plasmid, containing an insertion at least as large as phage Mu, was maintained unstably in the mutants examined.
Effect of Polyoxin D on Chitin Synthesis and Septum Formation in
Saccharomyces cerevisiae
Authors: Bowers Blair , Levin Gary , Cabib Enrico
Published: January 2020

The normal sequence of cell separation in
Saccharomyces cerevisiae
begins with the formation of a primary septum, presumably consisting of chitin, on which secondary septa are later deposited. In the presence of the antibiotic polyoxin D, a potent inhibitor of chitin synthetase, pairs of abnormal cells of two different types were observed by phase-contrast microscopy: the “exploded pair,” consisting of two lysed cells from which the cytoplasm had been extruded at the cell junction, and the “refringent pair,” consisting of two highly refractile cells joined by a thin bridge. Thus, in both cases the septal region appears to be affected. Observations with the electron microscope showed that the primary chitin septum was not formed in either of these cell types, and as a consequence secondary septa of varying thicknesses were laid down in an abnormal pattern. With [
3
H]glucose as carbon source the incorporation of tritium into the chitin of abnormal cells was inhibited about 90%, whereas the labeling of mannan was normal and that of glucan somewhat reduced. The effective concentrations of polyoxin D (0.1 to 1 mg/ml) were much greater than those required to inhibit chitin synthesis in vitro. Dimethylsulfoxide and amphotericin B, both known to increase cell permeability, enhanced the action of the antibiotic.
Lipids of
Sphaerophorus ridiculosis
: Plasmalogen Composition
Authors: Hagen Per-Otto
Published: January 2020

Lipid analyses of the anaerobic bacterium
Sphaerophorus ridiculosis
revealed that 24.2% of the polar lipids are the alk-1′-enyl glyceryl ether (plasmalogen) form. The major polar lipids, phosphatidylethanolamine (67.5%), phosphatidylglycerol (11.2%), cardiolipin (12.0%), and lyso-phosphatidylethanolamine (9.3%), contained 26.3, 7.8, 5.2, and 13.4% plasmalogen, respectively.
Genetic Analyses of the Polarity Alleles in Recombinants from Mitochondrial Genetic Crosses
Authors: Howell Neil , Hall Ruth M. , Linnane Anthony W. , Lukins H. B.
Published: January 2020

A number of minority recombinant and parental types from a heterosexual cross were analyzed for the ω allele they carry. It was found that recombinant progeny can be ω
−
, that minority parental types among the progeny can be ω
+
rather than ω
−
, and, finally, that certain of the results suggest that the ω locus may not be at the proximal end of the mitochondrial genetic map (Bolotin et al., 1971; Grivell et al., 1973) but rather may lie between the [
cap1-r/cap-s
] and [
ery1-r/ery-s
] loci.
Citrate Metabolism in
Aerobacter cloacae
Authors: O'Brien R. W. , Geisler Jarmila
Published: January 2020

Growth of
Aerobacter cloacae
on citrate either anaerobically or aerobically did not require and was not stimulated by the presence of Na
+
in the medium. Citrate was metabolized anaerobically via the fermentation pathway as evidenced by the (i) presence of oxalacetate decarboxylase, (ii) induction of citrate lyase, and (iii) repression of α-ketoglutarate dehydrogenase under anaerobic conditions. Thus, although all the other enzymes of the citric acid cycle were present in anaerobic cells, this pathway was not available for the metabolism of citrate. Citrate was metabolized aerobically via the citric acid cycle, since (i) citrate lyase but not oxalacetate decarboxylase was repressed and (ii) α-ketoglutarate dehydrogenase was induced under these conditions. The presence of Na
+
in the medium did not lead to a repression of α-ketoglutarate dehydrogenase as in the case of
Aerobacter aerogenes
. The oxalacetate decarboxylase was a soluble, constitutive enzyme, not activated by Na
+
nor inhibited by avidin. It was slightly inhibited by ethylenediaminetetraacetate but was not stimulated by Mg
2+
or Mn
2+
. Thus, this enzyme differed markedly in its properties from the same enzyme found in citrate-grown
A. aerogenes
.
Biotin Uptake by Cold-Shocked Cells, Spheroplasts, and Repressed Cells of
Saccharomyces cerevisiae
: Lack of Feedback Control
Authors: Cicmanec John F. , Lichstein Herman C.
Published: January 2020

Cold-osmotic-shocked cells and spheroplasts of
Saccharomyces cerevisiae
(ATCC 9896) display a biotin uptake system similar to that observed in intact cells. 2-Mercaptoethanol was found to inhibit biotin transport. Cells repressed for biotin uptake by growth in excess biotin (25 ng/ml) possess an energy-dependent transport system that has a

K
m

for biotin of 6.6 × 10
−7
M and a

V
max

equal to 39 pmol per mg (dry weight) per min. A similar

K
m

(6.4 × 10
−7
M) but a considerably higher

V
max

(530 pmol per mg (dry weight) per min) was determined for biotin uptake by cells grown in sufficient biotin (0.25 ng/ml). The

V
max

rates of biotin uptake by both repressed and derepressed cells were increased approximately 35-fold in the presence of glucose. These yeast cells appear to regulate their biotin uptake by two mechanisms. An exit system provides for immediate adjustments, whereas turnover of the transport system and repression of new synthesis establishes a slower adaptation to changes in the environment. Feedback inhibition was ruled out as a mechanism of regulation of transport.
Con
−
Mutants: Class of Mutants in
Escherichia coli
K-12 Lacking a Major Cell Wall Protein and Defective in Conjugation and Adsorption of a Bacteriophage
Authors: Skurray Ronald A. , Hancock Robert E. W. , Reeves Peter
Published: January 2020

We describe a new class of mutants of
Escherichia coli
K-12 defective in conjugation (Con
−
mutants). They lack a major protein of the outer membrane and are defective as recipients with Hfr and F′ donors and as recipients for several F-like R factors and Col factors. In the case of crosses with an Hfr donor, we have shown that the Con
−
recipient is defective in pair formation. The mutants are resistant to certain phages due to loss of receptor activity.
Interactions Between Exogenous Deoxyribonucleic Acid and Membrane Vesicles Isolated from
Bacillus subtilis
168
Authors: Joenje H. , Konings W. N. , Venema G.
Published: January 2020

Membrane vesicles isolated from competent cultures of
Bacillus subtilis
168 bound up to 20 μg of double-stranded deoxyribonucleic acid (DNA) per mg of membrane protein in the presence of ethylenediaminetetraacetate. The formation of the DNA-membrane complex was time, temperature, and pH dependent. Eighty per cent of the DNA could be removed from the complex by treatment with deoxyribonuclease I. Nevertheless, the DNA that remained attached to the vesicles appeared to have been attacked by the enzyme, suggesting that all the complexed DNA is located at the outer surface of the vesicles. Pretreatment of DNA with deoxyribonuclease I destroyed its affinity for the vesicles. The extent of binding decreased by the addition of Mg
2+
ions, especially at high DNA concentrations (more than 2 μg/ml). This effect was partially due to membrane-associated Mg
2+
-dependent endonucleolytic activity, which caused double-strand breaks in addition to single-strand nicks, and to exonuclease activity. The endonucleolytic activity was enhanced by heating the membranes at 80 C. DNA-membrane association was not markedly affected by sulfhydryl reagents, but was largely inhibited by formaldehyde. Endogenous competence-stimulating activity did not alter the DNA-binding capacity of the vesicles.
Characterization of
Salmonella typhimurium
Strains Sensitive and Resistant to Methionine Sulfoximine
Authors: Steimer-Veale Kathelyn , Brenchley Jean E.
Published: January 2020

Methionine sulfoximine inhibits the growth of
Salmonella typhimurium
at a concentration of 50 μM, and the addition of glutamine, but not glutamate, is sufficient to overcome this inhibition. The analogue causes 50% inhibition of glutamine synthetase activity at 2 to 4 μM and of glutamate synthase at 2 to 3 mM when these enzymes are assayed in vitro. No inhibition of glutamate dehydrogenase activity is observed at analogue concentrations as high as 50 mM. Two mutants selected for their resistance to methionine sulfoximine inhibition have a partial growth requirement for glutamine and a reduction in the glutamine synthetase and glutamate synthase activities. The sensitivity of the remaining glutamine synthetase activity in these mutants to methionine sulfoximine inhibition appears unaltered, and the lesions conferring the analogue resistance may not affect glutamine synthetase directly.
Polyamine Limitation of Growth Slows the Rate of Polypeptide Chain Elongation in
Escherichia coli
Authors: Jorstad Caroline M. , Morris David R.
Published: January 2020

The rate of polypeptide chain elongation during steady-state, polyamine-limited growth of a mutant of
Escherichia coli
was measured by two independent techniques. Analysis of polysome patterns gave values of 17.5 and 9.5 amino acids per s at 37 C in unstarved and polyamine-limited cells, respectively. From the kinetics of entry of labeled amino acids into polypeptides of defined molecular weights, values at 30 C of 10.1 and 5.8 amino acids per s were obtained for unstarved and polyamine-limited cultures, respectively. Correction of these values to 37 C resulted in rates of 15.0 and 8.7 amino acids per s. These results support the previous conclusion, based on the kinetics of β-galactosidase induction, that polyamine starvation decreases the rate of protein synthesis by limiting the velocity of polypeptide chain elongation.
More Precise Mapping of the Replication Origin in
Escherichia coli
K-12
Authors: Louarn Jacqueline , Funderburgh Martha , Bird Robert E.
Published: January 2020

The origin of replication in
Escherichia coli
K-12 was mapped by determining the rate of marker replication during a synchronous round of replication. Four isogenic strains were made lysogenic for λ
ind
−
and for phage Mu-1, with Mu-1 integrated into a different chromosomal location in each strain. Cultures were starved for amino acids to allow completion of chromosome replication cycles and then starved for thymine in the presence of amino acids, and a synchronous cycle of replication was initiated by the addition of thymine. Samples were exposed to radioactive thymidine at intervals, deoxyribonucleic acid was extracted, and the rate of marker replication was determined by deoxyribonucleic acid-deoxyribonucleic acid hybridization to filters containing Mu-1, λ, and
E. coli
deoxyribonucleic acid. The results confirm that the origin of replication is near
ilv
. The travel times of the replication forks, calculated from the data obtained for cultures with doubling times of approximately 40 and 61 min, are 40 and 52 min, respectively.
Energetics of Glycylglycine Transport in
Escherichia coli
Authors: Cowell James L.
Published: January 2020

The transport system for glycylglycine in
Escherichia coli
behaves like a shock-sensitive transport system. The initial rate of transport is reduced 85% by subjecting whole cells to osmotic shock, and glycylglycine is not transported by membrane vesicles. The energetics of transport was studied with strain ML 308-225 and its mutant DL-54, which is deficient in Ca
2+
- and Mg
2+
-stimulated adenosine 5′-triphosphatase (EC 3.6.1.3) activity. It is concluded that active transport of glycylglycine, like other shock-sensitive transport systems, has an obligatory requirement for phosphate bond energy, but not for respiration or the energized state of the membrane. The major evidence for this conclusion is as follows. (i) Uptake of glycylglycine is severely inhibited by arsenate. (ii) Oxidizable energy sources such as
d
-lactate, succinate, and ascorbate, which is mediated by
N
-methylphenazinium methylsulfate, cannot serve as energy sources for the transport of glycylglycine in DL-54, which lacks oxidative phosphorylation. (iii) When energy is supplied only from adenosine-5′-triphosphate produced by glycolysis (anaerobic transport assays with glucose as the energy source in DL-54), substantial uptake of glycylglycine is observed. (iv) When the Ca
2+
-Mg
2+
-adenosine triphosphatase activity is absent but substrate-level phosphorylations and electron transport are operating (glucose as the energy source in DL-54), transport of glycylglycine shows significant resistance to the uncouplers, dinitrophenol and carbonyl cyanide-
p
-trifluoromethoxyphenylhydrazone.
Mutants of
Escherichia coli
Defective in Membrane Phospholipid Synthesis: Mapping of
sn
-Glycerol 3-Phosphate Acyltransferase

K
m

Mutants
Authors: Cronan John E. , Bell Robert M.
Published: January 2020

plsB
mutants of
Escherichia coli
are
sn
-glycerol 3-phosphate auxotrophs which owe their requirement to a

K
m

defect in
sn
-glycerol 3-phosphate acyltransferase, the first enzyme in the phospholipid biosynthetic pathway. We have located the
plsB
gene at minute 69 of the
E. coli
genetic map, far removed from the gene defined by mutants with a temperature-sensitive
sn
-glycerol 3-phosphate acyltransferase. The
plsB
gene was cotransduced with the
dctA
locus, and the transduction data indicated that the clockwise gene order is
asd, plsB, dctA, xyl. plsB
−
is recessive to
plsB
+
and all acyltransferase

K
m

mutants tested lie very close to the
plsB
locus. Effective supplementation of
plsB
mutants was shown not to require a defective
glpD
gene.
Purification and Regulatory Properties of Fructose 1,6-Diphosphatase from
Hydrogenomonas eutropha
Authors: Abdelal Ahmed T. , Schlegel H. G.
Published: January 2020

Fructose diphosphatase of
Hydrogenomonas eutropha
H 16, produced during autotrophic growth, was purified 247-fold from extracts of cells. The molecular weight of the enzyme was estimated to be 170,000. The enzyme showed a pH optimum of 8.5 in both crude extracts and purified preparation. The shape of the pH curve was not changed in the presence of ethylenediaminetetraacetic acid. The enzyme required Mg
2+
for activity. The MgCl
2
saturation curve was sigmoidal and the degree of positive cooperativity increased at lower fructose diphosphate concentrations. Mn
2+
can replace Mg
2+
, but maximal activity was lower than that observed with Mg
2+
and the optimal concentration range was narrow. The fructose diphosphate curve was also sigmoidal. The purified enzyme also hydrolyzed sedoheptulose diphosphate but at a much lower rate than fructose diphosphate. The enzyme was not inhibited by adenosine 5′-monophosphate but was inhibited by ribulose 5-phosphate and adenosine 5′-triphosphate. Adenosine 5′-triphosphate did not affect the degree of cooperativity among the sites for fructose diphosphate. The inhibition by adenosine 5′-triphosphate was mixed and by ribulose 5-phosphate was noncompetitive. An attempt was made to correlate the properties of fructose diphosphatase from
H. eutropha
with its physiological role during autotrophic growth.
Defects of Two Temperature-Sensitive Lysyl-Transfer Ribonucleic Acid Synthetase Mutants of
Bacillus subtilis
Authors: Racine Francis M. , Steinberg William
Published: January 2020

Two temperature-sensitive mutants (
lysS1
and
lysS2
) of the lysyl-transfer ribonucleic acid synthetase (
l
-lysine:tRNA ligase [adenosine 5′-monophosphate], EC 6.1.1.6) of
Bacillus subtilis
have been isolated. Although protein synthesis is inhibited in both mutants at the restrictive temperature (42 to 45 C), the mutants remain viable in a minimal medium. In comparison with the wild-type lysyl-tRNA synthetase, the
l
-lysine-dependent exchange of [
32
P]pyrophosphate with adenosine 5′-triphosphate (ATP) for both mutant enzymes is decreased. The
lysS1
enzyme is completely defective in the ATP-dependent attachment of
l
-lysine to tRNA, whereas the
lysS2
enzyme has 3- to 10-fold reduced levels of this activity. Temperature-resistant transformants have wild-type enzyme levels, whereas partial revertants to temperature resistance have varied levels of enzyme activity. The attachment and exchange activities of the
lysS2
enzyme are more heat labile in vitro than the wild-type enzyme, as is the attachment activity of a partial revertant of the
lysS1
mutant. The
lysS1
and the
lysS2
lysyl-tRNA synthetases have higher apparent

K
m

values for lysine and ATP, in both the activation and the attachment reactions. The
lysS2
enzyme has a

V
max

for tRNA
lys
one-third that of the wild-type enzyme. Molecular weights of ∼150,000 for the wild-type and
lysS2
enzymes and ∼76,000 for the
lysS1
enzyme were estimated from sedimentation positions in sucrose density gradients assayed by the ATP-pyrophosphate exchange activity. We propose that the two mutations (
lysS1
and
lysS2
) directly affect the sites for exchange activity, but indirectly alter attachment activity as a consequence of defective subunit association.
Polysaccharide That May Serve as a Carbon and Energy Storage Compound for Sporulation in
Bacillus cereus
Authors: Slock J. A. , Stahly D. P.
Published: January 2020

An intracellular, glucose-containing polysaccharide accumulates in
Bacillus cereus
early in sporulation and is degraded at the time of spore maturation. This pattern of accumulation and degradation occurred when growth was limited by glucose or a component of yeast extract. These data suggest that the polysaccharide may be serving as a carbon and energy storage compound for sporulation. A somewhat similar pattern of accumulation and degradation of poly-β-hydroxybutyric acid (PHB) was shown earlier by Kominek and Halvorson (1965) to occur in
Bacillus cereus
. When cells were grown in a medium buffered strongly at pH 7.4, however, very little accumulation of PHB occurred. We have found that polysaccharide accumulates in cells grown in both the strong and weakly buffered media. Perhaps polysaccharide is the major carbon and energy storage compound when cells are grown under conditions preventing significant accumulation of PHB. The lack of polysaccharide accumulation during the exponential phase of growth may be an indication that the needed biosynthetic enzymes are controlled by catabolite repression during growth. The polysaccharide was purified and found to consist of glucose. The iodine absorption spectrum suggests a degree of branching between that of glycogen and amylopectin.
Isolation and Characterization of an
Escherichia coli
K-12 Mutant with a Temperature-Sensitive RecA
−
Phenotype
Authors: Lloyd Robert G. , Low Brooks , Godson G. Nigel , Birge Edward A.
Published: January 2020

A mutation that causes a temperature-sensitive RecA
−
phenotype was identified in a derivative of a PolA
−
strain that failed to grow at high temperature. The mutant allele (
recA200
) was shown to be linked to
cysC
, conferred a sharply temperature-sensitive, ultraviolet-sensitive Rec
−
phenotype in the range 35 to 42 C, and in crosses failed to show complementation at 42 C with Hfr's that transferred
recA
−
. Double mutants that carried both
recA200
and
polA
were examined for ability to grow and synthesize DNA at restrictive temperatures.
Purification and Properties of 3-Deoxy-
d
-Arabinoheptulosonic Acid-7-Phosphate Synthetase (trp) from
Escherichia coli
Authors: Camakaris J. , Pittard J.
Published: January 2020

The 3-deoxy-
d
-arabinoheptulosonic acid-7-phosphate synthetase which is subject to regulation by tryptophan has been partially purified from a strain of
Escherichia coli
K-12, in which this is the only functional form of this enzyme activity, and from a similar strain possessing a feedback-resistant form of the enzyme. Maximal observed inhibition by tryptophan of the feedback-sensitive enzyme was 56%. There was no evidence for cooperativity in the saturation of the enzyme with tryptophan or E4P. The molecular weights of the feedback-sensitive and feedback-resistant forms of the enzyme were the same (52,000), and no change was detected in the molecular weight of the feedback-sensitve enzyme in the presence of tryptophan. The effect of tryptophan analogues was tested to determine the nature of the tryptophan binding site. Treatment with ethylenediaminetetraacetic acid removed 80% of the activity of the feedback-sensitive enzyme. This activity was restored upon the addition of Co
2+
or Mn
2+
. Neither treatment with ethylenediaminetetraacetic acid nor addition of Co
2+
or Mn
2+
affected the activity of the feedback-resistant enzyme.
Neurospora crassa
Cytoplasmic Ribosomes: Isolation and Characterization of a Cold-Sensitive Mutant Defective in Ribosome Biosynthesis
Authors: Schlitt Steven C. , Russell Peter J.
Published: January 2020

Twenty-seven cold-sensitive mutants of
Neurospora crassa
were isolated by mutagenesis of wild-type conidia followed by filtration enrichment in complete medium at the nonpermissive temperature (10 C). Zone sedimentation analyses of cytoplasmic ribosomes isolated from the wild-type strain and from 14 of the mutant strains grown at 10 C indicate that one cold-sensitive mutant is defective in ribosome biosynthesis at that temperature: instead of the 2.3:1 mass ratio of 60
S
:37
S
ribosomal subunits characteristic of wild type, the mutant strain PJ30201 (called
crib-1
for cytoplasmic ribosome biosynthesis) exhibits a mass ratio of approximately 7.2:1. Ribosomal subunits synthesized by strain PJ30201 at 25 C are present in wild-type proportions. The cold-sensitive and ribosomal phenotypes segregate together in tetrads isolated from crosses between strain PJ30201 and the wild type indicating that a single nuclear gene mutation is probably responsible for both mutant phenotypes. The
crib-1
locus lies near the centromere in linkage group IV.
Interaction of Galactosaminoglycan with
Neurospora
Conidia
Authors: Glasgow James E. , Reissig José L.
Published: January 2020

The inactivation of
Neurospora crassa
conidia by galactosaminoglycan isolated from cultures of this organism was followed by measuring colony-forming ability and ability to take up radiolabeled metabolites. When kinetic data on the loss of transport function and on killing were analyzed by use of target theory, it appeared that few “hits” are required for inactivation. However, studies with radio-labeled galactosaminoglycan mucopolysaccharides showed that cells receiving a single lethal hit have approximately 10
5
galactosaminoglycan molecules bound to them.
Source of Energy for the
Escherichia coli
Galactose Transport Systems Induced by Galactose
Authors: Wilson David B.
Published: January 2020

The β-methyl-galactoside- and galactose-specific transport systems of
Escherichia coli
were shown by experiments involving inhibitors and the use of an adenosine triphosphatase mutant strain to utilize adenosine 5′-triphosphate or a related compound to drive active transport. These systems were shown to be unable to use the activated-membrane state. The galactose-specific transport system was shown to behave most like a member of the binding-protein class of transport systems by its response to osmotic shock and vesicle formation. These results extended to two sugar transport systems: the correlation between the source of energy and class of transport system found by Berger (1973) for amino acid transport systems. That is, binding-protein systems utilized adenosine 5′-triphosphate whereas membrane-bound systems utilized the activated-membrane state to drive active transport.
Isolation and Characterization of Bacteria That Grow on Methane and Organic Compounds as Sole Sources of Carbon and Energy
Authors: Patt Tom E. , Cole Gloria C. , Bland Judith , Hanson R. S.
Published: January 2020

Bacteria capable of growth on methane and a variety of complex organic substrates as sole sources of carbon and energy have been isolated. Conditions used to rigorously establish the purity of the cultures are described. One facultative methylotroph has been studied in detail. This organism has peripherally arranged pairs of intracytoplasmic membranes characteristic of obligate methylotrophs. This isolate apparently utilizes the serine pathway of formaldehyde fixation. The location of methane oxidizers in a dimictic lake indicates that these organisms prefer less than saturating levels of dissolved oxygen. Laboratory experiments confirmed the preference of these organisms for atmospheres containing less oxygen than air.
Uridine Diphosphoglucose Pyrophosphorylase Activity and Differentiation in the Acellular Slime Mold
Physarum polycephalum
Authors: Kuehn Glenn D.
Published: January 2020

The specific activity of uridine 5′-triphosphate:α-
d
-glucose 1-phosphate uridyltransferase (EC 2.7.7.9) (also called uridine 5′-diphosphate [UDP]-glucose pyrophosphorylase) has been found to increase up to eightfold during spherule formation by the slime mold
Physarum polycephalum
. The enzyme accumulates during the first 8 to 9 h after initiation of spherule formation, declines to basal levels found in vegetative microplasmodia by 15 h, and is undetectable in completed spherules. Specific activities for UDP-glucose pyrophosphorylase in vegetative microplasmodia range from 15 to 30 nmol of UDP-glucose formed per min per mg of protein, whereas accumulated levels during spherule formation can attain a specific activity as high as 125 nmol of UDP-glucose formed per min per mg of protein. The scheduling and extent of accumulation are critically dependent on an early log-phase age of microplasmodia originally induced to form spherules. Spherule induction by 0.2 M or 0.5 M mannitol delays this schedule in a variable and unpredictable manner. Spherule-forming microplasmodia which have accumulated high levels of UDP-glucose pyrophosphorylase spontaneously excrete the enzyme when transferred to salts medium containing 0.2 M or 0.5 M mannitol. The excreted enzyme is subsequently destroyed or inactivated. Studies with preferential inhibitors of macromolecular synthesis indicate that accumulation of UDP-glucose pyrophosphorylase requires concomitant protein synthesis and prior ribonucleic acid synthesis.
Phospholipid Composition of
Desulfovibrio
Species
Authors: Makula R. A. , Finnerty W. R.
Published: January 2020

The phospholipids of
Desulfovibrio desulfuricans
, Norway strain,
D. vulgaris
, and
D. gigas
were examined in relationship to their qualitative and quantitative composition.
D. desulfuricans
and
D. vulgaris
exhibited an essentially identical phospholipid composition consisting of phosphatidylethanolamine, phosphatidylglycerol, cardiolipin, and lysophosphatidylserine. Phosphatidylserine (10.9%) was present in
D. desulfuricans
but was not detected in
D. vulgaris. D. gigas
was found to contain only two phospholipids, phosphatidylethanolamine (30%) and phosphatidylglycerol (70%). An ornithine-containing lipid was detected in
D. gigas
which was not present in the other two
Desulfovibrio
species.
New Class of Streptomycin-Resistant Mutants Incompatible with
supX
Suppressor Mutations in
Salmonella typhimurium
Authors: Graf Lloyd H. , Kim Rosalind , Burns R. O.
Published: January 2020

Streptomycin-resistant colonies of
Salmonella typhimurium
appearing in platings of
supX
suppressors of strain
leu-500
are less variegated in size than are those derived from strain
leu-500
counterparts. Several of the streptomycin-resistant
leu-500
clones, furthermore, yield suppressors and revertants of the
leu-500
auxotrophy at unusually low rates, suggesting that they provide a genetic background inimicable to
supX
suppression. Two such “suppression-restrictive”
leu-500
streptomycin-resistant (
str
) mutants, designated strains M
1
and M
4
, were characterized as to their ability to receive the
trp-supX-cysB
linkage region by transduction. Coentry of a donor
supX
deletion mutation with the selected
trp
+
marker was not observed even though these sites display more than 10% linkage in control experiments. This was demonstrably the result of nonviability of the combined
supX
mutant, M
1
or M
4
streptomycin-resistant genotype, rather than the lack of suppression of the
leu-500
imparted auxotrophy. Both M
1
- and M
4
-type resistance was accompanied by pleiotropic effects resembling those caused by
strB
(nonribosomal)- rather than
strA
(ribosomal)-type resistance, but both restrictive mutants had a high upper limit of resistance corresponding to that of
strA
-type mutants. Transduction analyses indicated that the
str
character of neither the M
1
nor the M
4
strain was linked to the
strA
or the
strB
gene. These mutations define a previously undescribed locus, which we propose to designate
strC
, apparently related to streptomycin uptake rather than its intracellular action. Mutation at this locus is evidently incompatible with the inactivation or removal of the
supX
site, suggesting a functional association between products of the genes.
Genetics of biotin biosynthesis in Bacillus subtilis
Authors: Pai C H
Published: January 2020

Biotin auxotrophs of Bacillus subtilis were isolated and classified into three groups according to growth requirements, cross-feeding pattern, and biotin precursors excreted into culture supernatant fluids. Mutant genes were mapped by transduction using phage PBS1. All presently identified bio genes were linked to aroG with an order of bio-aroG-argA-leu-1. No linked markers were found to the left of the bio loci.
Genetic recombination in Nocardia mediterranei
Authors: Schupp T , Hutter R , Hopwood D A
Published: January 2020

A system of genetic recombination in Nocardia mediterranei ATCC 13685 is described. This strain produces a mixture of several rifamycin antibiotics. Using haploid recombinant selection and analysis procedures similar to those applied to Streptomyces coelicolor A3(2), 14 auxotrophic markers and 1 streptomycin resistance marker were located on a circular linkage map. The linkage map of N. mediterranei seems to be similar to that of S. coelicolor A3(2).
Factor 420-dependent tyridine nucleotide-linked hydrogenase system of Methanobacterium ruminantium
Authors: Tzeng S F , Wolfe R S , Bryant M P
Published: January 2020

Methanobacterium ruminantium was shown to possess a nicotinamide adenine dinucleotide phosphate (NADP)-linked factor 420 (F420)-dependent hydrogenase system. This system was also shown to be present in Methanobacterium strain MOH. The hydrogenase system of M. ruminantium also links directly to F420, flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), methyl viologen, and Fe-3 plus. It has a pH optimum of about 8 and an apparent Km for F420 of about 5 x 10-6 M at pH 8 when NADP is the electron acceptor. The F420-NADP oxidoreductase activity is inactive toward nicotinamide adenine dinucleotide (nad) and no NADPH:NAD or FADH2(FMNH2):NAD transhydrogenase system was detected. Neither crude ferredoxin nor boiled crude extract of Clostridium pasteuranum could replace F420 in the NADP-linked hydrogenase reaction of M. ruminantium. Also, neitther F420 nor a curde "ferredoxin" fraction from M. ruminantium extracts could substitute for ferredoxin in the pyruvate-ferredoxin oxidoreductase reaction of C. pasteurianum.
Factor 420-dependent pyridine nucleotide-linked formate metabolism of Methanobacterium ruminantium
Authors: Tzing S F , Bryant M P , Wolfe R S
Published: January 2020

Methanobacterium ruminantium was shown to possess a formate dehydrogenase which is linked to factor 420 (F420) as the first low-molecular-weight or anionic electron transfer coenzyme. Reduced F420 obtained from the formate dehydrogenase can be further linked to the formation of hydrogen via the previously described F420-dependent hydrogenase reaction, thus constituting an apparently simple formate hydrogenlyase system, or to the reduction of nicotinamide adenine dinucleotide phosphate via F420:nicotinamide adenine dinucleotide phosphate oxidoreductase. The results indicate that hydrogen and formate, the only known energy sources for M. ruminantium and many other methanogenic bacteria, should be essentially equivalent as sources of electrons in the metabolism of this organism.
Neurospora crassa temperature-sensitive mutant apparently defective in protein synthesis
Authors: Loo M
Published: January 2020

A temperature-sensitive mutant of Neurospora was isolated which appeared to be defective in the initiation of protein synthesis. The defect in mutant 34Cts was apparently due to a single gene mutation, and was recessive in heterokaryons. Conidial germination was normal and hyphal growth was nearly so in the mutant at 20 C, but both were greatly inhibited at 35 C. After 15 min at 35 C there was a reduced rate of protein synthesis, followed by decreases in ribonucleic acid and deoxyribonucleic acid synthesis. The percentage of ribosomes in polysomes declined at 35 C and the average size of polysomes decreased. Because the decrease in protein synthesis, it was believed that some part of the translational system may be affected by the mutation. Mutant 34Cts was given the designation psi-1.
Identification of the structural gene for glutamine synthetase in Klebsiella aerogenes
Authors: Deleo A B , Magasanik B
Published: January 2020

Mutations at two sites of the Klebsiella aerogenes chromosome, unlinked by transduction with phages PW52 and P1, result in the lack of enzymatically active glutamine synthetase. A mutation in the glnB site leads to a marked decrease in the formation of an apparently normal enzyme. Some of the mutations in the glnA site lead to the production of enzymatically inactive material capable of reacting with anti-glutamine synthetase serum. The revertant of a glnA mutant was found to produce a glutamine synthetase with less activity and less stability to heat than the enzyme of the wild type. These results locate the structural gene to the production of enzymatically inactive glutamine synthetase antigen, not subject to repression by exogenously added ammonia. This observation suggests that glutamine synthetase is itself involved in the regulation of the synthesis of glutamine synthetase.
Autolytic enzymes in hyphae of Aspergillus nidulans: their action on old and newly formed walls
Authors: Polacheck Y , Rosengerger R F
Published: January 2020

Walls, purified from hyphae of the ascomycete Aspergillus nidulans, autolyzed on incubation and liberated glucose, mannose, galactose, N-acetylglucosamine, and soluble oligosaccharides. Digestion proceeded at linear rates until approximately 3% of the wall polymers had been hydrolyzed and then slowed markedly. The change in the rate of autolysis was not due to loss of enzyme activity but was caused by the disappearance of a fraction of the wall which was highly susceptible to digestion. Radioactive labeling showed that this fraction was the newly formed wall. The new wall was highly susceptible to enzyme action both when it was deposited at the apex in growing hyphae or when deposited laterally in hyphae treated with cycloheximide. The relations between wall modification and apical growth are discussed.
Mapping of colicin E2 and colicin E3 plasmid deoxyribonucleic acid EcoR-1-sensitive sites
Authors: Inselburg J , Johns V
Published: January 2020

Colicin plasmids E2 and E3 (Col E2 and Col E3) deoxyribonucleic acid (DNA) has been shown to contain, respectively, two and three EcoR1 restriction endonuclease-sensitive sites. This was determined by measuring the DNA fragments generated after EcoR1 endonuclease treatment by agarose gel electrophoresis and electron microscopy. The structure of heteroduplex Col E2-col E3 DNA molecules formed from EcoR1-generated fragments permitted a localization of the EcoR1-sensitive sites on the plasmid chromosomes.
Regulation of acetohydroxy acid synthase in streptomycin-dependent Escherichia coli
Authors: Whitlow K J , Polglase W J
Published: January 2020

Growth of streptomycin-dependent mutants of Escherichia coli K-12 was insensitive to valine when dihydrostreptomycin was present in a nonlimiting concentration in glucose-salts medium. Acetohydroxy acid synthase was derepressed under these conditions, owing to relaxation of catabolite repression. Valine sensitivity and catabolite repression were restored when streptomycin-dependent E. coli K-12 mutants were grown with limiting dihydrostreptomycin. End product repression of acetohydroxy acid synthase under conditions of relaxed catabolite repression was effected by any two (or more) end products except the combination valine plus isoleucine, which caused derepression. Single end products had no detectable effect on acetohydroxy acid synthase formation.
Halide uptake by the filamentous ascomycete Neocosmospora vasinfecta
Authors: Miller A G , Budd K
Published: January 2020

The uptake of Cl minus by the ascomycetes Neocosmospora vasinfecta was investigated. Intramycelial concentrations of more than 55 mM (890-fold the external concentration) were reached. Accumulation was as inorganic Cl minus and nystatin induced total loss of mycelial Cl minus without extensive protein loss, implying that Cl minus retention was not due to binding to macromolecules. Cl minus transport was largely unidirectional with efflux being low under all conditions. Uptake was temperature dependent (maximal Arrhenius activation energy of 18.0 kcal/mol) and was severely reduced by KCN, dicyclohexylcarbodiimide, and anaerobiosis. A comparison with the inhibition of oxygen uptake under the same conditions implied that Cl minus transport was not directly coupled to aerobic electron transport. Cl minus uptake was a saturatable function of the external Cl minus concentration, and apparent Km values of 6.4 times 10-6 M and 10-4 M were calculated. Of the anions tested, only Br minus effectively inhibited Cl minus uptake and I minus, NO3 minus, SO4 minus 2, HCO3 minus, and H2PO4 minus were without effect. Cl minus uptake did not require concomitant cation uptake.
Effect of a leu-linked mutation on the valine sensitivity of acetohydroxy acid synthase activity in Escherichia coli
Authors: Kline E L , Brown C S , Umbarger H E
Published: January 2020

A spontaneous leu-linked mutation (ilvH2015) in Escherichia coli K-12 made the strain resistant to 1 mM valine and l mM glycylvaline (Val-r) and caused the isoleucine and valine biosynthetic enzyme, acetohydroxy acid synthase, to be less sensitive to feedback inhibition by valine than the wild-type enzyme. Transfer of the ilvDAC deletion into a strain carrying ilvH2015 abolished the effect of the marker on the acetohydroxy acid synthase and rendered it as sensitive to valine as the enzyme in the isogenic control strain without the Val-r marker under both repressing and limiting conditions. In contrast, auxotrophy caused by transfer of an ilvC lesion into the Val-r strain did not interfere with the effect of ilvH2015 on valine sensitivity of acetohydroxy acid synthase. In addition, the presence of the Val-r marker produced minor but significant pleiotropic effects on several other isoleucine and valine biosynthetic enzymes but did not cause derepression of the ilv gene cluster. These studies suggest some type of interaction between a product produced by a gene close to leu and the isoleucine and valine biosynthetic enzymes.
mut-25, a mutation to mutator linked to purA in Escherichia coli
Authors: Siegel E C , Ivers J J
Published: January 2020

The mutation mut-25 that results in a mutator phenotype is closely linked to purA on the chromosome of Escherichia coli. The gene order in this region is ampA mut-25 purA. purA mut-25 double mutants retained mutator activity indicating that mut-25 is not a mutation in the purA gene. The repair mutations uvrA6, recA56, and exrA1 had no effect on mutation frequencies in mut-25 strains, and mut-25 strains were normally resistant to ultraviolet irradiation. Frequencies of host range mutations were not increased in phages T1, T2, and T7 grown on mut-25 strains. mut-25 could act trans, reverting the trpA46 mutation either on the chromosome or on an F episome. The transitions AT yields GC (adenine-thymine yields guanine-cytosine) and GC yields AT were induced by mut-25.