bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydroxyethylthiazole Uptake in
Escherichia coli
: General Properties and Relationship Between Uptake and Thiamine Biosynthesis
Authors: Yamasaki Hiroshi , Sanemori Hiroshi , Yamada Kazuo , Kawasaki Takashi
Published: January 2020

Uptake of
35
S-hydroxyethylthiazole (4-methyl-5-hydroxyethylthiazole) by
Escherichia coli
intact cells was studied. Hydroxyethylthiazole was taken up in the presence and absence of glucose at the same rate. The uptake was almost proportional to a hydroxyethylthiazole concentration gradient up to 0.1 mM with no tendency of saturation, and reached a steady state within 2 min. When the cells were treated with 1 mM
N
-ethylmaleimide, about 50% inhibition of hydroxyethylthiazole uptake was observed. Hydroxyethylthiazole uptake was stimulated by the addition of hydroxymethylpyrimidine (2-methyl-4-amino-5-hydroxymethylpyrimidine), and this effect was further enhanced in the presence of glucose. For full activation of hydroxyethylthiazole uptake, 1 μM hydroxymethylpyrimidine was necessary in the presence of glucose. The rate of hydroxyethylthiazole uptake was almost linear up to 60 min in the presence of hydroxymethylpyrimidine and glucose. Hydroxymethylpyrimidine monophosphate and its pyrophosphate could not stimulate the uptake. Thiamine and 2-amino-hydroxyethylthiazole were inhibitory on hydroxyethylthiazole uptake in the presence of hydroxymethylpyrimidine and glucose.
N
-ethylmaleimide and 2, 4-dinitrophenol were also inhibitory. No stimulatory effect of hydroxymethylpyrimidine on hydroxyethylthiazole uptake was observed in mutant cells lacking either thiaminephosphate pyrophosphorylase or hydroxymethylpyrimidine monophosphate kinase. The possibility of direct participation of thiamine-synthesizing enzymes in hydroxyethylthiazole uptake was discussed.
Effect of Rifampin on the Structure and Membrane Attachment of the Nucleoid of
Escherichia coli
Authors: Dworsky P. , Schaechter M.
Published: January 2020

Deoxyribonucleic acid (DNA) of
Escherichia coli
was found to be attached to the cell membrane at about 20 points. This was determined by fractionation of X-irradiated cells with the M band (magnesium-Sarkosyl crystals) technique. The number of attachment points was computed from the relationship between the amount of DNA in M bands and the number of double-strand breaks introduced by the X-ray treatment. The number of attachment points was decreased fourfold by treatment of cells with rifampin. This effect was apparently due to the action of the drug on ribonucleic acid (RNA) polymerase since the drug did not affect a mutant whose RNA polymerase is resistant to rifampin. This suggests that there may be two classes of attachment points of DNA on the membrane, some of which are removed by rifampin treatment and some which are not. Rifampin treatment also resulted in the uncondensing of isolated nucleoids and in an axial appearance of the nucleoids in ultrathin sections. The results suggest that RNA polymerase plays a role, direct or indirect, in maintaining the structure of the bacterial nucleoid and in some of its attachment to the membrane.
Nuclear Apparatus of
Hyphomicrobium
Authors: Moore Richard L. , Hirsch Peter
Published: January 2020

The nuclear apparatus of
Hyphomicrobium
sp. strain B-522 is examined by various microscopy and radiolabeling techniques to determine its behavior during the reproductive cycle of these bacteria. The young, swarmer cell contains a single nucleoid comprised of a deoxyribonucleic acid (DNA) molecule with a molecular weight of 3.1 × 10
9
. After development of the swarmer into a mature mother cell with a hypha and bud, the nucleoid replicates and separates into two daughter nucleoids during the initial stages of bud formation. After further development of the bud, one of the daughter nucleoids in the mother cell is rapidly transferred through the hypha to the bud. Half of the old DNA strands pass to each consecutive generation of daughter cells, but only 43% of the stable ribonucleic acid is transferred. The role which the hypha plays in the developmental cycle of these bacteria is discussed, and a mechanism for nuclear transfer is proposed.
New Procedure for the Isolation of Membrane Vesicles of
Bacillus subtilis
and an Electron Microscopy Study of Their Ultrastructure
Authors: Konings W. N. , Bisschop A. , Veenhuis M. , Vermeulen C. A.
Published: January 2020

A rapid procedure for the isolation of membrane vesicles of
Bacillus subtilis
is described that minimizes the action of proteolytic enzymes, excreted by this organism, on the membrane proteins. The membrane vesicles obtained have, in addition to a low endogenous respiration rate, a low endogenous activity for transport of amino acids and carboxylic acids. In the presence of the electron donor, ascorbate-phenazine methosulfate, the transport activities for these compounds were comparable to the activities of intact cells. In addition, these activities were retained for a prolonged period of time. Electron microscopy examination of thin sections of the vesicles showed that the preparation consisted almost exclusively of membrane vesicles which were not contaminated with other cell components. The membrane vesicles, which are six to seven times smaller in diameter than protoplasts, often enclosed smaller vesicles. Freeze-etching of intact cells, protoplasts, and membrane vesicles showed that the orientation of the membrane of the vesicles was identical to the orientation of the plasma membrane in intact cells and protoplasts. This also held for the majority of the membranes of the enclosed vesicles, only 15% having the opposite orientation.
Developmental Block in Citric Acid Cycle Mutants of
Bacillus subtilis
Authors: Freese Elisabeth B. , Marks Cheryl L.
Published: January 2020

Mutants deficient in different enzymes of the citric acid cycle can be subdivided into two groups according to the frequency at which they produce heat-resistant spores in nutrient sporulation medium. However, the majority of cells can develop in this medium only to the axial filament stage I of sporulation; aconitase and isocitrate dehydrogenase mutants need the addition of glutamate to reach this stage.
The
lon
Gene and Degradation of β-Galactosidase Nonsense Fragments
Authors: Shineberg B. , Zipser D.
Published: January 2020

N-terminal β-galactosidase fragments are rapidly degraded in growing cells of
Escherichia coli
. Mutations in the
lon
gene are sufficient to enhance the stability of these polypeptides.
Transport and Catabolism of
d
-Fructose by
Spirillum itersonii
Authors: Hylemon P. B. , Krieg N. R. , Phibbs P. V.
Published: January 2020

Spirillum itersonii
ATCC 12639 utilized
d
-fructose but neither
d
-glucose nor
d
-gluconate as a sole source of carbon and energy. The substrate saturation kinetics for
d
-fructose and
d
-glucose uptake by whole cells indicated the presence of a carrier-mediated transport system for
d
-fructose but not for
d
-glucose. The
d
-fructose uptake activity was induced (10- to 12-fold increase) during growth on
d
-fructose-Casamino Acids (CA) or
d
-glucose-CA medium, but not CA alone.
d
-Fructose uptake activity was stimulated by Na
+
or Li
+
, but was inhibited by KCN, NaN
3
, 2,4-dinitrophenol, and
p
-chloromercuribenzoate. High specific activities of glucokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydratase, and 2-keto-3-deoxy-6-phosphogluconate aldolase were detected in extracts of cells cultured on
d
-fructose-CA medium. These enzymatic activities were undetectable in extracts of cells grown in CA or succinate-CA medium. No decrease in the maximally induced specific activities of these enzymes occurred after the addition of succinate to cells during exponential growth on
d
-fructose-CA. Fructose 1,6-diphosphate aldolase and glucose-6-phosphate isomerase specific activities were approximately the same irrespective of cultural conditions. These results indicated that
d
-glucose was not utilized by cells of
S. itersonii
because this bacterium was impermeable to this hexose.
Changes in Transfer Ribonucleic Acids Accompanying Encystment in
Acanthamoeba castellanii
Authors: McMillen Janis , Nazario M. , Jensen T.
Published: January 2020

Transfer ribonucleic acid (tRNA) from exponentially growing cells (trophozoites) and from precysts of
Acanthamoeba castellanii
were examined by reversed-phase column (RPC-2) chromatography. This system gave excellent resolution of isoaccepting species of tRNA. The tRNAs for 12 amino acids were studied. A comparison of trophozoite and precyst tRNA elution profiles revealed no apparent differences in the number of isoaccepting species of alanyl-, arginyl-, asparaginyl-, glycyl-, leucyl-, lysyl-, methionyl-, phenylalanyl-, tryptophanyl-, or valyl-tRNAs. Seryl-tRNAs from trophozoites were eluted as three components, whereas precyst seryl-tRNAs were eluted as only two components. Precharged trophozoite and precyst isoleucyl-tRNAs were both eluted as single components; however, post-chromatography charging of trophozoite tRNA resulted in three components of activity for tRNA
Ile
and only one component for precyst tRNA
Ile
. None of the observed changes could be attributed to differences in synthetases or to the presence of altered tRNA lacking the CCA terminus or partially degraded by nucleases. The possible significance of these observations is discussed.
Membrane Permeability and the Loss of Germination Factor from
Neurospora crassa
at Low Water Activities
Authors: Charlang Gisela , Horowitz N. H.
Published: January 2020

Neurospora crassa
conidia incubating in buffer at low water activities (a
w
) release a germination-essential component as well as 260-nm absorbing and ninhydrin-positive materials, regardless of whether an electrolyte or non-electrolyte is used to reduce a
w
. Chloroform and antibiotics known to increase cell-membrane permeability have a similar effect. This suggests that membrane damage occurs in media of low a
w
and that an increase in permeability is responsible for the release of cellular components. The damage caused in media of low a
w
is nonlethal in most cases, and the conidia recover when transferred to nutrient medium.
Localization of Polyribosomes Containing Alkaline Phosphatase Nascent Polypeptides on Membranes of
Escherichia coli
Authors: Cancedda Ranieri , Schlesinger Milton J.
Published: January 2020

A procedure has been developed for extracting membranes from bacterial cells under conditions that keep a large fraction of bacterial polyribosomes intact. Freeze-thawing spheroplasts in the presence of deoxyribonuclease, followed by differential centrifugation, permits a separation of free and membrane-associated polyribosomes. The latter fraction contains as much as 40% of cell ribosomal ribonucleic acid (RNA) and 55% of cell messenger RNA (mRNA). Nascent polypeptides were divided almost equally between the two fractions, but 70 to 80% of alkaline phosphatase nascent chains, detected both chemically and immunologically, were derived from polyribosomes associated with the bacterial membrane. Analysis of the fractions for mRNA specific for the
lac
and
trp
operons by RNA-deoxyribonucleic acid hydridization showed somewhat larger amounts on membrane than on free polyribosomes, but enrichment for nascent alkaline phosphatase (a secreted protein) on membranes was consistently greater, suggesting that polyribosomes making secreted proteins are more tightly bound to membranes. Electron micrographs of the membrane preparations show relatively intact membranes with clusters of polyribosomes on their inner surfaces.
Ultrastructural and Chemical Alteration of the Cell Envelope of
Pseudomonas aeruginosa
, Associated with Resistance to Ethylenediaminetetraacetate Resulting from Growth in a Mg
2+
-Deficient Medium
Authors: Gilleland H. E. , Stinnett J. D. , Eagon R. G.
Published: January 2020

Cells of
Pseudomonas aeruginosa
became resistant to the lytic effect of ethylenediametetraacetate (EDTA) when grown in a Mg
2+
-deficient medium. To correlate ultrastructural changes in the cell wall associated with the shift to EDTA-resistance, a freeze-etch study was performed. Upon fracturing, the outer cell wall membrane split down the hydrophobic center to reveal the outer (concave) and inner (convex) layers. The concave cell wall layer of EDTA-sensitive cells grown in Mg
2+
-sufficient medium contained spherical units resting on an underlying smooth support layer. Upon EDTA treatment, approximately one-half of these spherical units were extracted. Cells grown in Mg
2+
-deficient medium were resistant to EDTA. The concave cell wall layer of EDTA-resistant cells had increased numbers of highly compacted spherical units, giving this layer a disorganized appearance. The highly compacted appearance of this layer was unaltered by EDTA treatment. Thus, growth in Mg
2+
-deficient medium resulted in cells which were resistant to EDTA and which possessed an ultrastructurally altered outer layer of the outer cell wall membrane. Cell envelopes from EDTA-resistant cells were found to possess 18% less phosphorus, 16.4% more total carbohydrate, and 13.3% more 2-keto-3-deoxyoctonate than cell envelopes from EDTA-sensitive cells. There were also qualitative, but not quantitative, differences in the protein content of cell envelopes from EDTA-resistant and EDTA-sensitive cells.
Lactose and
d
-Galactose Metabolism in Group N Streptococci: Presence of Enzymes for Both the
d
-Galactose 1-Phosphate and
d
-Tagatose 6-Phosphate Pathways
1
Authors: Bissett Donald L. , Anderson Richard L.
Published: January 2020

Group N streptococci possess enzymes for the metabolism of
d
-galactose through both the
d
-galactose 1-phosphate pathway (Leloir pathway) and the
d
-tagatose 6-phosphate pathway.
Molecular Specificities of R Factor-Determined Beta-Lactamases: Correlation with Plasmid Compatibility
Authors: Hedges R. W. , Datta Naomi , Kontomichalou Polyxeni , Smith J. T.
Published: January 2020

Beta (β)-lactamases determined by 29 ampicillin resistance plasmids could be divided into two types. One, TEM-type, was very uniform with respect to substrate specificity but heterogeneous in absolute levels of β-lactamase activity. The TEM-type β-lactamase was determined by R factors of compatibility groups FII, Iα, Iε, N, C, A, T, W, P, L, and X, and by prophage φ Amp. The other type, characterized by the ability to hydrolyze oxacillin, was less common, showed lower absolute levels of activity, and was heterogeneous as regards substrate specificities. Oxacillin-hydrolyzing β-lactamases were determined by R factors of compatibility groups FI, Iα, N, C, and O.
Mutants of Group D
1
Salmonella
Carrying the Somatic Antigen of Group A Organisms: Isolation and Serological Characterization
Authors: Uchida Takahiro , Matsumoto Takeshi , Sasaki Terukatsu
Published: January 2020

O antigen mutants were obtained from
Salmonella durban
, a group D
1
organism, by treatment with
N
-methyl-
N′
-nitro-
N
-nitrosoguanidine. Serological studies demonstrated that the mutants lost the O-9 antigen factor of the parent organism but acquired the O-2 factor specific to group A
Salmonella
. Lipopolysaccharides of the mutant strains contained paratose which determines the specificity of O-2 factor. Tyvelose, present in the wild-type lipopolysaccharide, was not found in the mutants. H antigens and other biological characteristics of the mutant strains were the same as those of the wild-type organism. The present finding implies that group A
Salmonella
species might be derived from group D
1
organisms.
Saturated Fatty Acid Mutant ofSaccharomyces cerevisiaewith an Intact Fatty Acid Synthetase
Authors: Meyer Karl H. , Schweizer Eckhart
Published: January 2020

ASaccharomyces cerevisiaeconditional mutant, LK 181, is described which grows at 37 C only when supplemented with a saturated fatty acid of 12 to 14 carbon atoms chain length. At 22 C, however, no fatty acid supplementation is required for growth. The fatty acid concentration required for optimal growth at 37 C is about four times lower for LK 181 than for fatty acid synthetase-deficient mutants. In contrast to all fatty acid synthetase mutants so far examined, mutant LK 181 cannot grow with palmitic acid. The addition of palmitic, palmitoleic, or oleic acid to the culture medium prevents LK 181 growth at temperatures between 22 and 37 C. In vivo as well as in vitro, cellular de novo fatty acid biosynthesis from acetate is unimpaired in this mutant. It is suggested that endogenously synthesized fatty acids, due to their chain lengths of 16 and more carbon atoms, cannot supplement the mutant LK 181. It is concluded that the exogeneously supplied fatty acids act as allosteric effectors for a mutationally altered cellular protein to restore its biological function at elevated temperatures, rather than as a substitute for endogenously synthesized long-chain fatty acids.
C
4
-Dicarboxylate Transport in
Bacillus subtilis
Studied with 3-Fluoro-
l
-Erythro-Malate as a Substrate
Authors: Willecke Klaus , Lange Rita
Published: January 2020

Bacillus subtilis
cells grown in yeast extract medium accumulated 3-fluoro-
l
-erythro-[1,2-
14
C
2
]malate more than 30-fold from the surrounding medium. No metabolic products derived from 3-fluoro-
l
-erythro-malate could be detected in these cells.
l
-Malate competitively inhibited transport of 3-fluoro-
l
-erythro-malate. This malate analogue was itself a competitive inhibitor of
l
-malate uptake. Cells that had been grown in yeast extract supplemented with 5 mM
l
-malate showed a 10-fold increased affinity towards 3-fluoro-
l
-erythro-malate relative to cells grown in yeast extract medium with no added malate. Our results suggest that two transport systems for
l
-malate can be induced in
B. subtilis
. The first of these systems seems to effect uptake of C
4
-dicarboxylates (
l
-malate, succinate, and fumarate) in yeast extract medium. The second transport system (or possibly a modification of the first transport system) seems to be induced by addition of
l
-malate to this medium and is also functioning in malate minimal medium.
Superoxide Dismutase and Oxygen Toxicity in a Eukaryote
Authors: Gregory Eugene M. , Goscin Stephen A. , Fridovich Irwin
Published: January 2020

Saccharomyces cerevisiae
var.
ellipsoideus
contained 6.5 times more superoxide dismutase and 2.3 times more catalase when grown under 100% O
2
than when grown anaerobically. Growth under oxygen caused equal increases in both the cyanide-sensitive and the cyanide-insensitive superoxide dismutases of this organism. Experience with other eukaryotes has shown that cyanide sensitivity is a property of the cupro-zinc superoxide dismutase of the cytosol, whereas cyanide insensitivity is a property of the corresponding mangani-enzyme found in mitochondria. Cu
2+
, which has been shown to increase the radioresistance of yeast, also caused an increase of both of the superoxide dismutases of
S. cerevisiae
. Yeast which had been grown under 1 atm of O
2
were more resistant toward the lethal effects of 20 atm of O
2
than were yeast which had been grown in the absence of O
2
.
Escherichia coli
K-12
his
−
responded to growth under 1 atm of O
2
by increasing its content of catalase and of peroxidase, but not of superoxide dismutase. This contrasts with
E. coli
B, which was previously shown to respond to O
2
by a striking increase in superoxide dismutase.
E. coli
K-12
his
−
did not gain resistance toward 20 atm of O
2
because of having been grown under 1 atm of O
2
. Once again, this contrasts with the behavior of
E. coli
B. These data indicate that, in both prokaryotes and in eukaryotes, superoxide dismutase is an important component of the defenses against oxygen toxicity.
Isolation and Complementation of Mutants in Galactose Taxis and Transport
Authors: Ordal George W. , Adler Julius
Published: January 2020

By using a new screening method, we have obtained 43 new
Escherichia coli
mutants defective in ring formation on galactose swarm plates, which score for defects in chemotaxis or transport. They were complemented and compared with mutations previously known to lie in the galactose-binding protein or the β-methylgalactoside (
mgl
) permease, or both. The mutations were all found to lie in three genes, called
mglA, mglB
, and
mglC. mglB
codes for the gene specifying the binding protein. Based on co-transduction experiments,
mglA, mglB
, and
mglC
lie close to each other on the bacterial chromosome.
Carbon Dioxide Control of Lag Period and Growth of
Streptococcus sanguis
Authors: Repaske Roy , Repaske Anne C. , Mayer Ron D.
Published: January 2020

A carbon dioxide requirement for growth of
Streptococcus sanguis
was readily demonstrated in a fermentor where the gas atmosphere could be controlled. Growth at a maximum rate occurred immediately in response to the appropriate CO
2
concentration; growth stopped when CO
2
was deleted. Washed inocula consisting of exponentially growing cells required a minimum of 2.4% CO
2
, postexponential phase cells needed 1.2 to 1.8% CO
2
immediately and 2.4% CO
2
shortly thereafter, whereas stationary phase cells required three sequential increases in CO
2
from 0.3 to 1.8 to 2.4% within the first 90 min of growth. These CO
2
concentrations permitted each inoculum to initiate growth immediately at the same maximum rate. These results also showed that physiologically “old” cells had the same capacity for growth as “young” cells when the CO
2
concentrations were appropriate for the type of inoculum. Continued exponential growth of the culture at the same optimum rate required 2.4% CO
2
. Lower concentrations of CO
2
were rate limiting and the resulting exponential rate was proportional to the CO
2
concentration. The “normal” lag period of
S. sanguis
appears to be an artifact induced by a CO
2
deficiency.
Temperature-Induced Derepression of Tryptophan Biosynthesis in a Tryptophanyl-Transfer Ribonucleic Acid Synthetase Mutant of
Bacillus subtilis
Authors: Steinberg William
Published: January 2020

A tryptophanyl-transfer ribonucleic acid (tRNA) synthetase (
l
-tryptophan: tRNA ligase adenosine monophosphate, EC 6.1.1.2) mutant (
trpS1
) of
Bacillus subtilis
is derepressed for enzymes of the tryptophan biosynthetic pathway at temperatures which reduce the growth rate but still allow exponential growth. Derepression of anthranilate synthase in a tryptophan-supplemented medium (50 μg/ml) is maximal at 36 C, and the differential rate of synthesis is 600- to 2,000-fold greater than that of the wild-type strain or
trpS1
revertants. A study of the derepression pattern in the mutant and its revertants indicates that the 5-fluorotryptophan recognition site of the tryptophanyl-tRNA synthetase is an integral part of the repression mechanism. Evidence for a second locus, unlinked to the
trpS1
locus, which functions in the repression of tryptophan biosynthetic enzymes is presented.
Specific Electron Donor-Energized Transport of α-Aminoisobutyric Acid and K
+
into Intact Cells of a Marine Pseudomonad
Authors: Thompson John , MacLeod Robert A.
Published: January 2020

The transport of α-aminoisobutyric acid and K
+
into K
+
-depleted cells of a marine pseudomonad (ATCC 19855) was stimulated strongly by ethanol, reduced nicotinamide adenine dinucleotide (NADH), and ascorbate-reduced
N, N, N′, N′
-tetramethyl-
p
-phenylenediamine. In the presence of the quinone inhibitor 2-heptyl-4-hydroxyquinoline-
N
-oxide, only ascorbate-reduced
N, N, N′, N′
-tetramethyl-
p
-phenylenediamine was active. Primary and secondary, but not tertiary, alcohols from ethanol to
n
-amyl alcohol stimulated both α-aminoisobutyric acid and K
+
transport and were oxidized by the cells. Malate and succinate, which were oxidized rapidly by the cells, had little or no capacity to energize the transport of α-aminoisobutyric acid into K
+
-depleted cells but were partially effective in promoting K
+
uptake. Ethanol stimulated the transport of α-aminoisobutyric acid into K
+
-preloaded cells. The transport of both α-aminoisobutyric acid and K
+
was inhibited 20% by iodoacetate, 85% by
N
-ethylmaleimide, and 90 to 100% by both NaCN and
p
-chloromercuribenzoate. The addition of Na
3
Fe(CN)
6
permitted the ethanol-induced transport of α-aminoisobutyric acid into K
+
-preloaded cells in the presence of NaCN, but little or no uptake of α-aminoisobutyric acid or of K
+
into K
+
-depleted cells under the same conditions. The transport of α-aminoisobutyric acid into K
+
-depleted cells required both K
+
and an electron donor. The oxidation of NADH and ethanol by K
+
-depleted cells was stimulated strongly by K
+
. Parallels between these studies and those with membrane vesicles show that results with membrane vesicles of the marine pseudomonad have physiological significance for the intact cells. The results support the conclusion that the energy for the active transport of both α-aminoisobutyric acid and K
+
into cells of this organism is provided by electron flow through a region of the respiratory chain lying between cytochrome
c
and O
2
.
Inhibition of
lacZ
Gene Translation Initiation in
trp-lac
Fusion Strains
Authors: Reznikoff William S. , Michels Corinne A. , Cooper Terrance G. , Silverstone Allen E. , Magasanik Boris
Published: January 2020

Different levels of β-galactosidase are found in various
trp-lac
fusion strains. These levels of β-galactosidase fall within a 60-fold range. The amount of thiogalactoside transacetylase activity detected in these same strains only varies 10-fold and is found in amounts greater than those predicted from the β-galactosidase levels. The observation that the β-galactosidase and thiogalactoside transacetylase levels are not directly proportional, that the
lacZ
messenger ribonucleic acid (mRNA) levels are not proportional to the β-galactosidase activity, that, at least for the one fusion strain tested, the SuA polarity suppressor does not affect the β-galactosidase level, and that, in all but one strain, the β-galactosidase activity appears to reside in normal β-galactosidase molecules suggests that the disproportionately low production of β-galactosidase is due to a decrease in the frequency of translation initiation of
lacZ
mRNA in these strains. Several mechanisms are proposed to explain this decrease. Some possible bases for the disproportional production of β-galactosidase and thiogalactoside transacetylase are also described. The preferred explanation for these disproportional enzyme levels is that only a fraction of the full complement of ribosomes need initiate translation at
lacZ
for the functional synthesis of
lac
mRNA to occur and that once the
lac
ribonucleic acid is made a full complement of ribosomes can bind at internal translation initiation sites at
Y
and
A
.
Oxaluric Acid: a Non-Metabolizable Inducer of the Allantoin Degradative Enzymes in
Saccharomyces cerevisiae
Authors: Sumrada Roberta , Cooper Terrance G.
Published: January 2020

Saccharomyces cerevisiae
degrades allantoin in five steps to ammonia, CO
2
, and glyoxylate. Previously we demonstrated that allophanic acid, the last intermediate of the pathway, was required for induction of all five degradative enzymes. The data presented here indicate that oxaluric acid, an allophanate analogue, is capable of serving as a non-metabolizable inducer. Oxaluric acid brings about a high level of induction even in strains lacking urea carboxylase. Induction observed with parabanic acid was found to result from its spontaneous breakdown to oxaluric acid.
Two Pathways of Glutamate Fermentation by Anaerobic Bacteria
Authors: Buckel Wolfgang , Barker H. A.
Published: January 2020

Two pathways are involved in the fermentation of glutamate to acetate, butyrate, carbon dioxide, and ammonia—the methylaspartate and the hydroxyglutarate pathways which are used by
Clostridium tetanomorphum
and
Peptococcus aerogenes
, respectively. Although these pathways give rise to the same products, they are easily distinguished by different labeling patterns of the butyrate when [4-
14
C]glutamate is used as substrate. Schmidt degradation of the radioactive butyrate from
C. tetanomorphum
yielded equally labeled propionate and carbon dioxide, whereas nearly all the radioactivity of the butyrate from
P. aerogenes
was recovered in the corresponding propionate. This procedure was used as a test for the pathway of glutamate fermentation by 15 strains (9 species) of anaerobic bacteria. The labeling patterns of the butyrate indicate that glutamate is fermented via the methylaspartate pathway by
C. tetani, C. cochlearium
, and
C. saccarobutyricum
, and via the hydroxyglutarate pathway by
Acidaminococcus fermentans, C. microsporum, Fusobacterium nucleatum
, and
F. fusiformis
. Enzymes specific for each pathway were assayed in crude extracts of the above organisms. 3-Methylaspartase was found only in clostridia which use the methylaspartate pathway, including
Clostridium
SB4 and
C. sticklandii
, which probably degrade glutamate to acetate and carbon dioxide by using a second amino acid as hydrogen acceptor. High levels of 2-hydroxyglutarate dehydrogenase were found exclusively in organisms that use the hydroxyglutarate pathway. The data indicate that only two pathways are involved in the fermentation of glutamate by the bacteria analyzed. The methylaspartate pathway appears to be used only by species of
Clostridium
, whereas the hydroxyglutarate pathway is used by representatives of several genera.
Relation of R Factor and Chromosomal β-Lactamase with the Periplasmic Space
Authors: Smith J. T. , Wyatt J. M.
Published: January 2020

The release of several R factor and chromosomal β-lactamases by osmotic shock treatment was studied. It was found that those β-lactamases with a molecular weight of about 20,000 were released, but those with a molecular weight of about 30,000 to 44,000 were not released during osmotic shock. This differential release did not depend on whether the structural genes were on the chromosome or on the genome of an R factor. The release or retention of the β-lactamases appeared to be a characteristic of the enzyme rather than the host cell since the same results were obtained when the R factors were harbored by a variety of host bacteria. Studies with bacteria which produced more than one β-lactamase showed that each enzyme reacted independently to the presence of other β-lactamases produced by the host bacterium.
Plasmid Replication and the Induced Synthesis of Colicins E1 and E2 in
Escherichia coli
Authors: Durkacz Barbara W. , Kennedy Christina K. , Sherratt David J.
Published: January 2020

Induction of colicins E1 and E2 in
Escherichia coli
occurs when plasmid synthesis has been inhibited either by nalidixic acid or by lack of deoxyribonucleic acid polymerase I. Moreover, colicin E1 and E2 synthesis induced by mitomycin C and exposure to chloramphenicol is not associated with a large increase in circular plasmid deoxyribonucleic acid. The mean plasmid content of cells in populations having a low spontaneous frequency of colicin-producing cells because of growth at low temperature or because of the presence of
rec
A
−
or
crp
−
alleles, is not significantly different to that in wild-type cells grown at 37 C.
d
- and
l
-Isoleucine Metabolism and Regulation of Their Pathways in
Pseudomonas putida
Authors: Conrad Robert S. , Massey Linda K. , Sokatch John R.
Published: January 2020

Pseudomonas putida
oxidized isoleucine to acetyl-coenzyme A (CoA) and propionyl-CoA by a pathway which involved deamination of
d
-isoleucine by oxidation and
l
-isoleucine by transamination, oxidative decarboxylation, and beta oxidation at the ethyl side chain. At least three separate inductive events were required to form all of the enzymes of the pathway:
d
-amino acid dehydrogenase was induced during growth in the presence of
d
-isoleucine; branched-chain keto dehydrogenase was induced during growth on 2-keto-3-methylvalerate and enzymes specific for isoleucine metabolism; tiglyl-CoA hydrase and 2-methyl-3-hydroxybutyryl-CoA dehydrogenase were induced by growth on isoleucine, 2-keto-3-methylvalerate, 2-methylbutyrate, or tiglate. Tiglyl-CoA hydrase and 2-methyl-3-hydroxybutyryl-CoA dehydrogenase were purified simultaneously by several enzyme concentration procedures, but were separated by isoelectric focusing. Isoelectric points, pH optima, substrate specificity, and requirements for enzyme action were determined for both enzymes. Evidence was obtained that the dehydrogenase catalyzed the oxidation of 2-methyl-3-hydroxybutyryl-CoA to 2-methylacetoacetyl-CoA. 2-Methyl-3-hydroxybutyryl-CoA dehydrogenase catalyzed the oxidation of 3-hydroxybutyryl-CoA, but
l
-3-hydroxyacyl-CoA dehydrogenase from pig heart did not catalyze the oxidation of 2-methyl-3-hydroxybutyryl-CoA; therefore, they appeared to be different dehydrogenases. Furthermore, growth on tiglate resulted in the induction of tiglyl-CoA hydrase and 2-methyl-3-hydroxybutyryl-CoA dehydrogenase, but these two enzymes were not induced during growth on crotonate or 3-hydroxybutyrate.
Transcriptional Control in the
l
-Arabinose Operon of
Escherichia coli
B/r
Authors: Cleary Paul P. , Englesberg Ellis
Published: January 2020

The structural genes involved in
l
-arabinose metabolism are regulated by the protein product of the
araC
gene. This protein functions as both an activator and repressor of enzyme synthesis in this gene complex. Using λ
h80dara
deoxyribonucleic acid in hybridization studies, we have shown that the
ara
operon, including structural genes
araB, araA
, and
araD
, is transcribed in the direction
araB
to
araD
and that initiation of transcription of these genes requires an active
araC
gene. The half-life of this message, approximately 3 min at 30 C, is the same in the presence or absence of the
araC
protein in the activator state. However, an unexplained 2-min lag in decay of
ara
messenger ribonucleic acid that does not occur in decay of
lac
messenger ribonucleic acid is observed. This lag period requires activated
araC
protein.
New Chromatographic Form of Phenylalanine Transfer Ribonucleic Acid from
Escherichia coli
Growing Exponentially in a Low-Phosphate Medium
Authors: Mann Michael B. , Huang P. C.
Published: January 2020

Reversed-phase chromatography has been used to detect the presence of a new form of phenylalanyl-transfer ribonucleic acid (Phe-tRNA) from
Escherichia coli
growing exponentially in media containing low but nonlimiting levels of inorganic phosphate. The amount of this extra Phe-tRNA form is greatest in slowly growing cells (0.8 generations/h), and becomes negligible in media supporting a rapid growth rate (2.14 generations/h).
Asparagine Utilization in
Escherichia coli
Authors: Willis R. C. , Woolfolk C. A.
Published: January 2020

Asparagine-requiring auxotrophs of
Escherichia coli
K-12 that have an active cytoplasmic asparaginase do not conserve asparagine supplements for use in protein synthesis. Asparagine molecules entering the cell in excess of the pool required for use of this amino acid in protein synthesis are rapidly degraded rather than accumulated. Supplements are conserved when asparagine degradation is inhibited by the asparagine analogue 5-diazo-4-oxo-
l
-norvaline (DONV) or mutation to cytoplasmic asparaginase deficiency. A strain deficient in cytoplasmic asparaginase required approximately 260 μmol of asparagine for the synthesis of 1 g of cellular protein. The cytoplasmic asparaginase (asparaginase I) is required for growth of cells when asparagine is the nitrogen source. This enzyme has an apparent

K
m

for
l
-asparagine of 3.5 mM, and asparaginase activity is competitively inhibited by DONV with an apparent

K
i

of 2 mM. The analogue provides a time-dependent, irreversible inhibition of cytoplasmic asparaginase activity in the absence of asparagine.
Biosynthesis of Carotenoids in
Brevibacterium
sp. KY-4313
Authors: Hsieh L. K. , Lee Tung-Ching , Chichester C. O. , Simpson K. L.
Published: January 2020

The biosynthesis of 4-keto and 4,4′-diketo carotenoids in
Brevibacterium
sp. KY-4313 was studied. Echinenone and canthaxanthin were isolated from the cultures grown on a medium containing several
n
-alkanes. When glutathione was added to the bacterial cultures, the formation of canthaxanthin was inhibited while β-carotene and its hydroxy derivatives accumulated. It is suggested that these 4-hydroxy compounds, isocryptoxanthin, isozeaxanthin, and 4-hydroxy-4′-keto-β-carotene, are intermediates in the biosynthesis of canthaxanthin. In the presence of 2-(4-chlorophenylthio)-triethylamine hydrochloride or nicotine, lycopene and neurosporene accumulated. The β-carotene level decreased slightly but β-zeacarotene remained unchanged. β-carotene and its derivatives were resynthesized upon removal of the inhibitors. It was concluded that cyclization can take place at either the neurosporene or lycopene level in
Brevibacterium
sp. KY-4313.
Electron Microscope Analysis of Partial Denaturation of F Factor Deoxyribonucleic Acid
Authors: Hsu Ming-Ta
Published: January 2020

Partial denaturation pattern of sex factor deoxyribonucleic acid of
Escherichia coli
was studied by electron microscopy. Clustering of the adenine-plusthymine-rich regions in one part of the molecule was revealed. The positions of these regions were located on the physical map of F by analyzing the partial denaturation pattern of heteroduplexes between F and F-prime factors with various parts of F sequences deleted.
Negative Chemotaxis in
Escherichia coli
Authors: Tso Wung-Wai , Adler Julius
Published: January 2020

Several methods for detecting or measuring negative chemotaxis are described. Using these, we have surveyed a number of chemicals for their ability to repel
Escherichia coli
. Although most of the repellents are harmful compounds, harmfulness is neither necessary nor sufficient to make a compound a repellent. The repellents can be grouped into at least nine classes according to (i) competition experiments, (ii) mutants lacking certain of the negative taxes, and (iii) their chemical structure. The specificity of each class was studied. It is suggested that each class corresponds to a distinct chemoreceptor. Generally, non-chemotactic mutants lack both positive and negative chemotaxis, and
l
-methionine is required for both kinds of taxis. Repellents at very low concentrations are not attractants, and attractants at very high concentrations are not repellents.
Alternate Forms of the Resistance Factor R1 in
Proteus mirabilis
Authors: Meyer Richard
Published: January 2020

The resistance factor R1 may exist in either of two stable physical states in
Proteus mirabilis
PM-1. In one case, the R1 deoxyribonucleic acid (DNA) has a buoyant density of 1.711 g/cm
3
and replicates under stringent control. Cells harboring R1 in this form may transfer drug resistance by conjugation. In the other case, R1 DNA shows two buoyant density classes at 1.707 and 1.714 g/cm
3
. The 1.714 g/cm
3
component is replicated under a degree of relaxed control, and strains carrying this form generally cannot transfer drug resistance by conjugation. Intracellular amounts of the R factor-coded enzyme, chloramphenicol acetyltransferase, did not correspond to amounts of plasmid DNA in
Proteus
, and the enzyme was present in lower amounts than in
Escherichia coli
. It is proposed that the two states of R1 in
Proteus
may represent stable associated and dissociated forms of the plasmid.
Cell Lysis of
Bacillus subtilis
Caused by Intracellular Accumulation of Glucose-1-Phosphate
Authors: Prasad Chandan , Freese Ernst
Published: January 2020

Mutants deficient in both glucose-6-phosphate dehydrogenase and phosphoglucose isomerase lysed 4 to 5 h after growth in nutrient medium containing glucose, or after prolonged incubation if the medium contained galactose. The lysis could be prevented by the addition of any other rapidly metabolizable carbon source such as fructose, glucosamine, or glycerol. The glucose-induced lysis was also abolished by introduction of a third mutation lacking phospho-glucose mutase activity but not by a third mutation lacking uridine diphosphate-glucose pyrophosphorylase or teichoic acid glucosyl transferase activity. Galactose-induced lysis was prevented only if the additional mutation abolished the uridine diphosphate-glucose pyrophosphorylase activity. The results showed that lysis was caused by the intracellular accumulation of glucose-1-phosphate, which in turn inhibited at least one of the two enzymes that convert glucosamine-6-phosphate to
N
-acetyl glucosamine-6-phosphate.
Topology and Growth of the Intracytoplasmic Membrane System of
Rhodopseudomonas spheroides
: Protein, Chlorophyll, and Phospholipid Insertion into Steady-State Anaerobic Cells
Authors: Kosakowski M. H. , Kaplan S.
Published: January 2020

An equilibrium density gradient centrifugation study involving the separation of “old” and “new” membranes has been developed to determine the manner in which protein, lipid, and chlorophyll are incorporated into growing intracytoplasmic membranes (chromatophores) of
Rhodopseudomonas spheroides
. Chromatophores derived from cells grown in an H
2
O-medium had a density of 1.175 to 1.180 g/cm
3
and were readily separable from chromatophores having a density of 1.220 to 1.230 isolated from cells grown in a 70% D
2
O-medium. After a shift from “D
2
O-” to “H
2
O”-based media, only hybrid chromatophores derived from a combination of “heavy” (old) and “light” (new) chromatophore material could be detected. The experimentally determined, median density values for the growing intracytoplasmic membrane system followed a theoretically determined profile which was calculated from the density of full “heavy” and full “light” material assuming random, homogeneous incorporation of new material into old membrane. The distribution of the radioactive labels for protein (leucine) and chlorophyll (delta-aminolevulinic acid) were identical and showed a reproducible displacement of the “old” material to the heavy side of the optical density at 365 nm (OD
365
) absorbance and a displacement of the “new” material to the light side of the OD
365
absorbance profile. Specific phospholipid growth showed no displacement for either the “old” or “new” material from the median absorbance profile.
Properties of a Thermosensitive Asporogenous Filamentous Mutant of
Bacillus megaterium
Authors: Hitchins Anthony D. , Sadoff Harold L.
Published: January 2020

Mutant TH14 of
Bacillus megaterium
ATCC 19213 is thermosensitive and defective in cell-division septation and spore formation at the restrictive temperature (39 C). As a consequence, the mutant forms multinucleate aseptate filaments and is asporogenic. The mutation does not result in any qualitative compositional changes in extractable membrane proteins. At the restrictive temperature, the mutant membrane has a reduced content of a small molecular weight protein(s). A membrane protein(s) with a molecular weight of nearly 80,000 appears to be partially derepressed in the mutant grown at the restrictive temperature. In addition, numerous unidentified spherical inclusions of fairly uniform size (diameter approximately 100 nm) are present in the cytoplasm at the restrictive temperature. They are especially concentrated at only one pole of each filament. Filamentous growth of the mutant is less sensitive to penicillin than growth in the rod form. Growth in either form is equally sensitive to
d
-cycloserine at the concentrations used for selection of the mutant. Temperature shift-up experiments suggest that one to two rounds of deoxyribonucleic acid (DNA) replication occur before the phenotypic expression of the mutation occurs. The septations after these replication events can be either two-division septations or a single-division septation plus a subsequent sporulation septation. This conclusion, coupled with previously reported work, supports the hypothesis that the early stages of sporulation represent a modified cell division.
Dissociation of a Degradative Plasmid Aggregate in
Pseudomonas
Authors: Chakrabarty A. M.
Published: January 2020

The infectious plasmid OCT, which specifies a set of dissimilatory enzymes responsible for the degradation of
n
-octane, has been shown to be an aggregate of a noninfectious OCT plasmid and an infectious plasmid with sex factor activity. The infectious plasmid, which can be eliminated from the cells of
Pseudomonas putida
by mitomycin C treatment without loss of the OCT plasmid and vice versa, has been designated as factor K. The infectious plasmid (factor K) is not only responsible for the mobilization of OCT, but also mobilizes chromosomal genes at a frequency of 10
−2
to 10
−3
per donor cell. Whereas OCT is incompatible with another degradative plasmid, CAM, factor K appears to be compatible with it.
Nitrogen Repression of the Allantoin Degradative Enzymes in
Saccharomyces cerevisiae
Authors: Bossinger June , Lawther Robert P. , Cooper Terrance G.
Published: January 2020

Saccharomyces cerevisiae
can utilize allantoin as a sole nitrogen source by degrading it to ammonia, “CO
2
,” and glyoxylate. We have previously shown that synthesis of the allantoin degradative enzymes is contingent upon the presence of allophanate, the last intermediate in the pathway. The reported repression of arginase by ammonia prompted us to ascertain whether or not the allantoin degradative system would respond in a similar manner. We observed that the differential rates of allantoinase and allophanate hydrolase synthesis were not decreased appreciably when comparing cultures grown on urea to those grown on urea plus ammonia. These experiments were also performed using the strain and conditions previously reported by Dubois, Grenson, and Wiame. We found allophanate hydrolase production to be twofold repressed by ammonia when that strain was grown on glucose-urea plus ammonia medium. If, however, serine or a number of other readily metabolized amino acids were provided in place of ammonia, production of the allantoin degradative enzymes was quickly (within 20 min) and severely repressed in both strains. We conclude that repression previously attributed to ammonia may result from its metabolism to amino acids and other metabolites.
Regulation of One-Carbon Biosynthesis and Utilization in
Escherichia coli
Authors: Meedel Thomas H. , Pizer Lewis I.
Published: January 2020

The regulation of several enzymes involved in one-carbon metabolism was studied in a mutant of
Escherichia coli
K-12 defective in
S
-adenosylmethionine synthetase. The mutant that was reported to have a low endogenous concentration of
S
-adenosylmethionine had elevated levels of
N
-5, 10-methylene tetrahydrofolate reductase and serine transhydroxymethylase, but the level of
N
-5, 10-methylene tetrahydrofolate dehydrogenase was not altered. These results suggest that
S
-adenosylmethionine plays a role in the regulation of one-carbon production and utilization. An enzyme system that cleaved glycine to one-carbon units was demonstrated. The enzymes responsible for the cleavage of glycine were induced by exogenous glycine but were independent of
S
-adenosylmethionine or purine levels in the cell.
Purification and Properties of a Diacetyl Reductase from
Escherichia coli
Authors: Silber Philip , Chung Howard , Gargiulo Paul , Schulz Horst
Published: January 2020

A reduced nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reductase with the ability to reduce diacetyl has been isolated from
Escherichia coli
and has been purified 800-fold to near homogeneity. The product of the reduction of diacetyl was shown to be acetoin. The enzyme proved to catalyze the oxidation of NADPH in the presence of both uncharged α- and β-dicarbonyl compounds. Even monocarbonyl compounds showed slight activity with the enzyme. On the basis of its substrate specificity, it is suggested that the enzyme functions as a diacetyl reductase. In contrast to other diacetyl reductases, the one reported here is specific for NADPH and does not possess acetoin reductase activity. The pH optimum of this enzyme was found to be between 6 and 7. The maximal velocity for the NADPH-dependent reduction of diacetyl was determined to be 9.5 μmol per min per mg of protein and the

K
m

values for diacetyl and NADPH were found to be 4.44 mM and 0.02 mM, respectively. The molecular weight was estimated by gel filtration on Sephadex G-100 to be approximately 10,000.