bluuebunny/crossref_metadata_2025 huggingface dataset:
Derepression of Arylsulfatase Synthesis in
Aerobacter aerogenes
by Tyramine
Authors: Adachi Toshiro , Murooka Yoshikatsu , Harada Tokuya
Published: January 2020

Studies were made on the effect of tyramine on arylsulfatase synthesis in mutants of
Aerobacter aerogenes
ATCC 9621 deficient in enzymes involved in tyramine degradation. As shown previously, some sulfur compounds, such as inorganic sulfate, repressed enzyme synthesis while others, such as methionine, did not. Tyramine caused derepression of enzyme synthesis, which is repressed by inorganic sulfate. The present work showed that, although tyramine readily derepressed arylsulfatase synthesis, metabolites of tyramine in either the wild-type or mutant strains did not, so that the derepression is due to the particular structure of tyramine. Kinetic studies on the cells indicated that incorporation of sulfur into protein and enzyme synthesis occurred on supply of either a sulfur compound, which did not cause repression, or of tyramine, which caused derepression, irrespective of the type of sulfur compound added, if any.
Purification and Properties of
Lactobacillus plantarum
Inducible Malic Enzyme
Authors: Park Shinae L. , Guttman Helene N.
Published: January 2020

Inducible malic enzyme (
l
-malate:NAD oxidoreductase [decarboxylating], EC 1.1.1.39) was isolated from
Lactobacillus plantarum
and purified about 100-fold with 27% yield of the original activity. Kinetic studies with the purified malic enzyme yielded the following results: pH optimum, 7.6 to 8.0;

K
m

for
l
-malate, 0.38 mM;

K
m

for NAD, 0.072 mM; and

K
m

for MnCl
2
, 0.048 mM. It was shown that this enzyme was inhibited by high concentrations of substrate and nicotinamide adenine dinucleotide (NAD), indicating it may be regulated by substrate or NAD. Molecular weight of 130,000 ± 10,000 was determined by Sephadex gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point, determined by isoelectrofocusing, was 4.3 at 7 C. Isoelectrofocusing also resolved three active peaks which focused at pH 4.19, 4.31, and 4.40.
Abolition of Crypticity of
Arthrobacter pyridinolis
Toward Glucose and α-Glucosides by Tricarboxylic Acid Cycle Intermediates
Authors: Sobel Mark E. , Wolfson Ellen B. , Krulwich Terry A.
Published: January 2020

Arthrobacter pyridinolis
cannot grow on glucose as sole carbon source, although the cells possess catabolic enzymes of the Embden-Meyerhof and pentose phosphate pathways as well as a complete tricarboxylic acid cycle. Crypticity toward glucose is abolished by a period of growth in a medium containing malate, succinate, citrate, or fumarate in addition to glucose. Other carbon sources, which support as rapid growth as does malate (e.g. asparagine), do not enable the cells to use glucose. Malate, succinate, citrate, and fumarate abolish crypticity toward glucose only in the second phase of diauxic growth after the tricarboxylic acid cycle intermediate has been depleted. This sequence of events, first observed in growth curves, has been verified by experiments in which the incorporation of radioactive substrates into trichloroacetic acid-insoluble cellular material was followed. The tricarboxylic acid cycle intermediates which confer the ability to utilize glucose also enhance the utilization of the αglucosides sucrose and maltose. The mechanism whereby growth on certain tricarboxylic acid cycle intermediates confers the subsequent ability to grow on glucose is related to a transport system for glucose and α-glucosides. This transport system has been assayed by measuring the uptake of [
1
-
14
C
]-2-deoxyglucose. Cells grown for varying periods of time in asparagine, asparagine plus glucose, or malate do not transport 2-deoxyglucose. Cells from malate-glucose cultures that are in the exponential phase of growth on glucose can transport 2-deoxyglucose. Transport of 2-deoxyglucose shows Michaelis-Menten kinetics with a

K
m

of 2.9 × 10
−4
M. It is competitively inhibited by glucose, α-methylglucopyranoside, and maltose. The transport of 2-deoxyglucose is inhibited by cyanide, dinitrophenol, azide, and
N
-ethylmaleimide, but not by malonate or fluoride. No phosphoenolpyruvate:
d
-glucose phosphotransferase activity has been detected, and the 2-deoxyglucose transported into the cell is not phosphorylated.
Glycolaldehyde Is a Precursor of Pyridoxal Phosphate in
Escherichia coli
B
Authors: Tani Yoshiki , Dempsey Walter B.
Published: January 2020

Carbon-labeled glycolaldehyde prepared from [
14
C]serine was used to supply the nutritional requirement of a pyridoxineless auxotroph of
Escherichia coli
. Pyridoxal phosphate isolated from bacteria so grown was found to have incorporated the radioactive glycolaldehyde with little dilution. The radioactivity which was unincorporated into pyridoxal phosphate was recovered almost entirely in the culture fluid. The results establish for the first time that glycolaldehyde is indeed a natural precursor of pyridoxal phosphate or it is readily converted to such a precursor.
Purification and Characterization of Ferredoxin-Nicotinamide Adenine Dinucleotide Phosphate Reductase from a Nitrogen-Fixing Bacterium
Authors: Yoch Duane C.
Published: January 2020

Evidence suggesting that
Bacillus polymyxa
has an active ferredoxin-NADP
+
reductase (EC 1.6.99.4) was obtained when NADPH was found to provide reducing power for the nitrogenase of this organism; direct evidence was provided when it was shown that
B. polymyxa
extracts could substitute for the native ferredoxin-NADP
+
reductase in the photochemical reduction of NADP
+
by blue-green algal particles. The ferredoxin-NADP
+
reductase was purified about 80-fold by a combination of high-speed centrifugation, ammonium sulfate fractionation, and chromatography on Sephadex G-100 and diethylaminoethyl-cellulose. The molecular weight was estimated by gel filtration to be 60,000. A small amount of the enzyme was further purified by polyacrylamide gel electrophoresis and shown to be a flavoprotein. The reductase was specific for NADPH in the ferredoxin-dependent reduction of cytochrome
c
and methyl viologen diaphorase reactions; furthermore, NADP
+
was the acceptor of preference when the electron donor was photoreduced ferredoxin. The reductase also has an irreversible NADPH-NAD
+
transhydrogenase (reduced-NADP:NAD oxidoreductase, EC 1.6.1.1) activity, the rate of which was proportional to the concentration of NAD (

K
m

= 5.0 × 10
−3
M). The reductase catalyzed electron transfer from NADPH not only to
B. polymyxa
ferredoxin but also to the ferredoxins of
Clostridium pasteurianum, Azotobacter vinelandii
, and spinach chloroplasts, although less effectively. Rubredoxin from
Clostridium acidi-urici
and azotoflavin from
A. vinelandii
also accept electrons from the
B. polymyxa
reductase. The pH optima for the various reactions catalyzed by the
B. polymyxa
ferredoxin-NADP reductase are similar to those of the chloroplast reductase. NAD and acetyl-coenzyme A, which obligatorily activate NADPH- and NADH-ferredoxin reductases, respectively, in
Clostridium kluyveri
, have no effect on
B. polymyxa
reductase.
Isolation of a Bisulfite Reductase Activity from
Desulfotomaculum nigrificans
and Its Identification as the Carbon Monoxide-Binding Pigment P582
Authors: Akagi J. M. , Adams Verna
Published: January 2020

Crude preparations of
Desulfotomaculum nigrificans
were found to reduce bisulfite to trithionate, thiosulfate, and sulfide. The bisulfite reductase of this organism was partially purified and observed to reduce bisulfite to trithionate as the major product and with thiosulfate and sulfide as minor products. The enzyme exhibited spectral properties identical to the carbon monoxide-reacting pigment (P582) isolated from this organism. It is concluded that the bisulfite reductase of
D. nigrificans
is P582 and that this organism utilizes a pathway which involves trithionate during the reduction of bisulfite to sulfide.
Membrane Synthesis in Synchronous Cultures of
Bacillus subtilis
168
Authors: Sargent Michael G.
Published: January 2020

Synthesis of bacterial membranes has been investigated in
Bacillus subtilis
by examining incorporation of amino acids and glycerol into the protein and lipid of membranes of synchronous cultures. A simple reproducible fractionation scheme divides cellular proteins into three classes (i) truly cytoplasmic, (ii) loosely membrane bound, released by chelating agents, and (iii) tightly membrane bound. These comprise approximately 75, 10, and 15%, respectively, of cellular proteins in this organism. Incorporation of radioactivity into these fractions, using steady-state and pulse labeling has been followed during the cell cycle. Cytoplasmic proteins and the loosely membrane-bound proteins are labeled at an exponential rate throughout the cell cycle. The membrane fraction is labeled discontinuously in the cell cycle, with periods of rapid synthesis over the latter part of the cycle and a period with no net synthesis during the early part of the cycle. Pulse labeling indicates that synthesis of membrane occurs at a linear rate that doubles at a fixed time in each cycle, which coincides with the period of zero net synthesis. Rates of membrane synthesis measured by pulse labeling during the period of rapid membrane synthesis are significantly less than indicated by steady-state labeling. These discrepancies are consistent with the hypothesis that during the cell cycle certain proteins are added to the membrane from the cytoplasm and that during the period of zero net synthesis there is an efflux of proteins from the membrane. Evidence in favor of this has been presented. The activity of succinic dehydrogenase (a representative of class c) varies in a step-wise manner with periods of rapid increase, approximately coincident with bursts of membrane protein synthesis, alternating with periods without any increase in activity. The activities of malate dehydrogenase (class a) and reduced nicotinamide adenine dinucleotide dehydrogenase (class b) increased throughout the cell cycle. Phospholipid synthesis is continuous throughout the cell cycle.
Biotin Uptake in Biotin Regulatory Mutant of
Escherichia coli
Authors: Pai C. H.
Published: January 2020

A transport system for biotin in
Escherichia coli
is regulated by biotin and is not affected by the mutation (
bioR
) that causes the constitutive synthesis of the
bio
operon enzymes.
Kinetics of Reaction of
Escherichia coli
Ribosomal Proteins toward
N
-Ethylmaleimide
Authors: Rosenberg Manuel , Berman Denis , Chang F. N.
Published: January 2020

The kinetics of reaction of the exposed ribosomal proteins from
Escherichia coli
toward
N
-ethylmaleimide (NEM) have been studied. While most of the proteins from the 30
S
subunit react rapidly with NEM and plateau levels can be reached, most of the proteins from the 50
S
subunit show biphasic uptake kinetics. Furthermore, differences have been observed in the reactivity of proteins toward NEM depending on whether the protein is in the free subunit or in the 70
S
ribosome.
Gene-Enzyme Relationships of Aromatic Acid Biosynthesis in
Bacillus subtilis
Authors: Hoch James A. , Nester Eugene W.
Published: January 2020

Mutants have been isolated which correspond to every step concerned with the biosynthesis of the aromatic amino acids in
Bacillus subtilis
. Each mutant has been characterized, and the lesion it bore was analyzed by deoxyribonucleic acid transformation and PBS-1 mediated transduction. The biochemical analysis revealed that each of the mutations appears to have affected a single enzyme, except for two groups of pleiotropic mutations. All
aroF
mutants (chorismic acid synthetase) lack dehydroquinic acid synthetase (
aroB
) activity. The gene that specifies
aroB
is closely linked to the gene coding for the
aroF
enzyme. Both genes are a part of the
aro
cluster. Mutants lacking chorismate mutase activity also lack
d
-arabino-heptulosonic acid-7-phosphate synthetase and shikimate kinase activity, presumably as a result of these three activities forming a multi-enzyme complex. Another mutant, previously undescribed, had been isolated. The affected gene codes for the tyrosine and phenylalanine aminotransferase activity. All of the mutations have been located on the
B. subtilis
genome except those in the genes specifying shikimate kinase activity and tyrosine-phenylalanine aminotransferase activity.
Protein Synthesis During the Differentiation of Sporangia in the Water Mold
Achlya
Authors: Timberlake William E. , McDowell Larry , Cheney John , Griffin David H.
Published: January 2020

During the synchronous differentiation of sporangia in the absence of added nutrients, the water mold
Achlya bisexualis
(Coker and Couch) actively synthesized protein. Inhibition of protein synthesis at any time during the sporulation process completely inhibited further differentiation. Large changes in the rate of radioactive amino acid uptake resulted in changes in the specific activity of the cellular amino acid pool. The rate of protein synthesis was calculated from the amino acid pool specific activity and the incorporation of isotope into protein. During the 1st h after induction of the sporulation process, the rate of protein synthesis increased to two times the initial value. The amino acid precursors for this synthesis were supplied by the degradation of preexisting protein. Proteolytic enzyme activity assayed in vitro increased in proportion to the in vivo rates of protein synthesis and degradation. Differentiation was accompanied by a slight decline in dry weight of the mycelium as well as by a decrease in the protein content, whereas the relative size of the amino acid pools remained constant.
Characterization of the Membranes of
Thermoplasma acidophilum
Authors: Smith Paul F. , Langworthy Thomas A. , Mayberry W. R. , Hougland A. E.
Published: January 2020

Thermoplasma acidophilum
grows optimally under aeration at 59 C and pH 2. Both intact cells and membranes disaggregate below pH 1 and above pH 5, producing no sedimentable particles. Increase in ionic strength at pH 5 or below results in cellular lysis and membrane disaggregation. Membranous components produced by lysis at alkaline pH reaggregate upon reduction of both pH and ionic strength. Osmotic environment plays little role in cellular stability. Membranes prepared by sonic lysis at pH 5 exhibit vesicular structures and are composed of multiple proteins. Although the amino acid composition of the membrane proteins is similar to other mycoplasmal membranes, the number of free amino and carboxyl groups is less than half of those in
Acholeplasma
. Reduction of the number of free carboxyl groups results in membrane stabilization over a wide range of pH. Increase in the number of free amino groups reverses the stability of membranes relative to pH. Acidophily in
Thermoplasma
can be related to a significant reduction in repulsing negative charges on the membrane proteins.
Location of the Structural Gene for Fructose-1,6-Diphosphate Aldolase in
Escherichia coli
Authors: Ruffler Dieter , Böck August
Published: January 2020

Gene
fda
has been mapped, by co-transduction, between
thyA
and
serA
on the
Escherichia coli
chromosome.
General Method for the Isolation of Plasmid Deoxyribonucleic Acid
Authors: Guerry Patricia , LeBlanc D. J. , Falkow Stanley
Published: January 2020

Plasmid deoxyribonucleic acid (DNA) ranging from 5 × 10
6
to 65 × 10
6
daltons may be isolated from chromosomal DNA by the preferential precipitation of the higher-molecular-weight chromosomal DNA in the presence of sodium lauryl sulfate and a high concentration of NaCl.
Isolation of a Specialized Lambda Transducing Bacteriophage Carrying the Beta Subunit Gene for
Escherichia coli
Ribonucleic Acid Polymerase
Authors: Kirschbaum Joel B. , Konrad E. Bruce
Published: January 2020

A heat-inducible lysis-defective λ prophage has been integrated directly into the
E. coli
chromosome at a site (
bfe
) very closely linked to the ribonucleic acid polymerase mutation
rif
d
, a dominant rifampin resistance allele. This unusual lysogen has facilitated the isolation of specialized transducing phages conferring rifampin resistance to sensitive cells, and carrying at least the β subunit gene of RNA polymerase in intact form.
Nitrosoguanidine Assay of Episomal Integration in
Escherichia coli
Authors: Lloveres Cristina P. , Cerdá-Olmedo E.
Published: January 2020

Mutations affecting utilization of lactose and resistance to the male-specific phages f1, f2, and Qβ tend to occur simultaneously more often than expected by chance in Hfr strains whose origin of transfer is close to the genes for lactose utilization, but not in F
+
strains. Strains derived from the Hfr, but exhibiting poor ability to transfer early chromosomal genes, may or may not show this comutation phenomenon. These results support the concept that the F factor is integrated into the Hfr chromosome during vegetative growth, but is autonomous in the F
+
strains and could serve as an assay for episomal localization.
Messenger Ribonucleic Acid Synthesis and Degradation in
Escherichia coli
During Inhibition of Translation
Authors: Pato Martin L. , Bennett Peter M. , Von Meyenburg Kaspar
Published: January 2020

Various aspects of the coupling between the movement of ribosomes along messenger ribonucleic acids (mRNA) and the synthesis and degradation of mRNA have been investigated. Decreasing the rate of movement of ribosomes along an mRNA does not affect the rate of movement of some, and possibly most, of the RNA polymerases transcribing the gene coding for that mRNA. Inhibiting translation with antibiotics such as chloramphenicol, tetracycline, or fusidic acid protects extant mRNA from degradation, presumably by immobilizing ribosomes, whereas puromycin exposes mRNA to more rapid degradation than normal. The promoter distal (3′) portion of mRNA, synthesized after ribosomes have been immobilized by chloramphenicol on the promoter proximal (5′) portion of the mRNA, is subsequently degraded.
Genetic Studies of Leucine Biosynthesis in
Bacillus subtilis
Authors: Ward Jonathan B. , Zahler Stanley A.
Published: January 2020

The mutations in a series of leucine auxotrophs isolated after treatment with nitrosoguanidine, ultraviolet light, and ICR-191 have been mapped between
ilvC
and
pheA
on the
Bacillus subtilis
chromosome. A fine structure map of the region was constructed by transformation. Analysis of several strains by assaying levels of their leucine bioysnthetic enzymes has shown that the region encodes three enzymes. The order of the genes with respect to the biosynthetic steps catalyzed by the gene products is 1–3–2.
Synchronous Cultures of
Bacillus subtilis
Obtained by Filtration with Glass Fiber Filters
Authors: Sargent Michael G.
Published: January 2020

A simple method of potentially wide applicability for obtaining synchronous cultures of
Bacillus subtilis
based on size selection is described. Using glass fiber filters, a population (about 1 to 2% of the parent population) can be obtained substantially enriched for small cells which grow synchronously. A method for rapidly concentrating dilute suspensions of cells is described.
Formation of Hydrogen and Formate by
Ruminococcus albus
Authors: Miller Terry L. , Wolin M. J.
Published: January 2020

Radioisotopic growth studies with specifically labeled
14
C-glucose confirmed that
Ruminococcus albus
, strain 7, ferments glucose mainly by the Embden-Myerhof-Parnas pathway to acetate, ethanol, formate, CO
2
, H
2
, and an unidentified product. Cell suspensions and extracts converted pyruvate to acetate, H
2
, CO
2
, and a small amount of ethanol. Formate was not produced from pyruvate and was not degraded to H
2
and CO
2
, indicating that formate was not an intermediate in the production of H
2
and CO
2
from pyruvate. Cell extract and
14
C-glucose growth studies showed that the H
2
-producing pyruvate lyase reaction is the major route of H
2
and CO
2
production. An active pyruvate-
14
CO
2
exchange reaction was demonstrable with cell extracts. The
14
C-glucose growth studies indicated that formate, as well as CO
2
, arises from the 3 and 4 carbon positions of glucose. A formate-producing pyruvate lyase system was not demonstrable either by pyruvate-
14
C-formate exchange or by net formate formation from pyruvate. Growth studies with unlabeled glucose and labeled
14
CO
2
or
14
C-formate suggest that formate arises from the 3 and 4 carbon positions of glucose by an irreversible reduction of CO
2
. The results of the studies on the time course of formate production showed that formate production is a late function of growth, and the rate of production, as well as the total amount produced, increases as the glucose concentration available to the organism increases.
Glucosylation of Lipopolysaccharide in
Salmonella
: Mutants Negative for O Antigen Factor 12
2
Authors: Mäkelä P. Helena
Published: January 2020

In salmonella O group B, the O antigen factor 12
2
is created by glucosylation at C4 of the galactose units of the O side chains; phage-determined glucosylation at C6 of these galactose units yields factor 1. 12
2
-negative mutants were isolated from 12
2
+
(stable) parents (genetically
oafR
+st
). All 20 mutants studied were stable in respect of their 12
2
character. In eight of them, lysogenization by phage P22 resulted in the appearance of the 12
2
factor—these were interpreted to be defective in the enzyme(s) needed to synthesize the glucose-lipid intermediate that participates in both 12
2
- and 1-specific glucosylation; the corresponding cistron was termed
oafE
. This “complementation” assay also demonstrated that the P22 genome can determine the synthesis of this glucose-lipid intermediate. The 12
2
character in the
oafE
−
mutants became variable after P22 lysogenization, corresponding to factor 1 variation normally determined by this phage. In the remaining 12 mutants, P22 caused the appearance of a variable factor 1, but not of 12
2
. The lesion in all the 12
2
mutants was mapped close to the gene
purE
at min 19 of the
Salmonella
map. This is the same area where the locus
oafR
that controls the variation (stable or variable, + or −) of 12
2
had been previously mapped. The results suggest the presence of a 12
2
glucosylation operon in this region.
Formate Dehydrogenase of
Clostridium thermoaceticum
: Incorporation of Selenium-75, and the Effects of Selenite, Molybdate, and Tungstate on the Enzyme
Authors: Andreesen Jan R. , Ljungdahl Lars G.
Published: January 2020

The formation of the nicotinamide adenine dinucleotide phosphate-dependent formate dehydrogenase in
Clostridium thermoaceticum
is stimulated by the presence of molybdate and selenite in the growth medium. The highest formate dehydrogenase activity was obtained with 2.5 × 10
−4
M Na
2
MoO
4
and 5 × 10
−5
Na
2
SeO
3
. Tungstate but not vanadate could replace molybdate and stimulate the formation of formate dehydrogenase. Tungstate stimulated activity more than molybdate, and in combination with molybdate the stimulation of formation of formate dehydrogenase was additive. Formate dehydrogenase was isolated from cells grown in the presence of Na
2
75
SeO
2
, and a correlation was observed between bound
75
Se and enzyme activity.
Nutritional Alteration of the Fatty Acid Composition of a Thermophilic
Bacillus
Species
Authors: Daron Harlow H.
Published: January 2020

The fatty acid composition of a thermophilic
Bacillus
sp. was altered by the addition of isobutyrate, isovalerate, α-methylbutyrate, leucine, and isoleucine to the growth medium. With isobutyrate, 81% of the fatty acids had 16 carbon atoms and 79% were iso-fatty acids with an even number of carbon atoms. With leucine, 58% of the fatty acids had 15 carbon atoms and 86% were iso-fatty acids with an odd number of carbon atoms. With isoleucine, 72% of the fatty acids had 17 carbon atoms and 88% were anteiso-fatty acids with an odd number of carbon atoms. Thus, by altering the composition of the growth medium, cells were produced in which the majority of the fatty acids had either 15, 16, or 17 carbons and belonged to each of the three groups of branched-chain fatty acids. The wide variation observed in the fatty acid composition makes it unlikely that any specific branched-chain fatty acid is required for vital functions.
Conjugal Deoxyribonucleic Acid Replication by
Escherichia coli
K-12: Effect of Nalidixic Acid
Authors: Fenwick R. G. , Curtiss Roy
Published: January 2020

During the conjugal transfer of the R64-11 plasmid at 42 C from donor cells thermosensitive for vegetative deoxyribonucleic acid (DNA) synthesis to recipient minicells, the plasmids are conjugally replicated in the donor cells. This conjugal replication is inhibited by nalidixic acid, and the degree of inhibition is comparable to the reduction in the amount of plasmid DNA transferred to the recipient minicells in the presence of the drug. In addition, the size of DNA transferred to the minicells and the fraction of conjugally replicated DNA in the donor cells that can be isolated as closed-circular plasmid DNA under alkaline conditions are both reduced by nalidixic acid. When the drug is added to a mating that is underway, the rate of conjugal replication is immediately reduced. This change is accompanied by a reduction in the amount of conjugally replicated DNA in the donor cells that can be isolated as closed-circular plasmid DNA. Furthermore, conjugally replicated plasmid DNA that is not associated with the donor cell membrane becomes membrane bound after the addition of nalidixic acid.
Single-Strand Breaks in Deoxyribonucleic Acid and Viability Loss During Deoxyribonucleic Acid Synthesis Inhibition in
Escherichia coli
Authors: Hill Walter E. , Fangman Walton L.
Published: January 2020

The effects of deoxyribonucleic acid (DNA) synthesis inhibition brought about in four different ways—thymidine starvation, nalidixic acid, hydroxyurea, and
dnaB
mutation—were examined in isogenic strains of
Escherichia coli
K-12. Three parameters were examined to determine whether there are strict correlations among them: (i) the extent of DNA synthesis inhibition; (ii) cell survival; and (iii) the rate of breakage of DNA molecules. There was no significant correlation between the extent of DNA synthesis inhibition and the rate of viability loss caused by the four DNA synthesis inhibitors, nor was there a strict correlation between the rate of occurrence of single-strand breaks in DNA and loss of viability. During treatment with hydroxyurea (0.1 M), no viability loss was observed and little, if any, single-strand breakage of DNA occurred. Both thymidine starvation and nalidixic-acid (20 μg/ml) treatment resulted in viability loss and breakage of DNA. For these latter two inhibitors, the two events appeared to be associated because greater rates of both viability loss and DNA breakage were observed for nalidixic acid compared with thymidine starvation. However, viability loss need not be associated with extensive breakage of DNA as demonstrated with a temperature-sensitive DNA synthesis mutant; at 39 C, viability loss occurred at a high rate without significant DNA breakage. With the other agents, the amount of DNA breakage accumulated when a cell population has sustained an average of one lethal hit was estimated to be about 30 single-strand breaks per genome. Differences in chromosomal and episomal breakage rates were observed.
Sites of Cellular Autolysis in
Lactobacillus acidophilus
Authors: Higgins M. L. , Coyette J. , Shockman G. D.
Published: January 2020

Ultrastructural changes which occur during cellular autolysis of
Lactobacillus acidophilus
strain 63AM Gasser in 0.05 M citrate buffer, pH 5.0, were examined. Early in the process, randomly distributed electron-dense patches were seen on the wall surface, along with an accompanying eversion of mesosomes. Later, after a loss of about 20% of the initial cellular turbidity, dissolution from the outside of nascent cross walls was seen. This observation was related to the normal process of cell separation. After this stage, short lengths of the cylindrical portion of the wall appeared to be completely removed in a random manner over the entire surface. This dissolution produced gaps in the wall which allowed the extrusion of membrane and cytoplasm. Although membrane was usually extruded through one major, polar, subpolar, or septal site, other secondary points of membrane extrusion were also frequently seen in the same cell section.
Particular Influence of Leucine Peptides on Lysyl-Transfer Ribonucleic Acid Ligase Formation in a Mutant of
Escherichia coli
K-12
Authors: Buklad Naomi E. , Sanborn Dianne , Hirshfield Irvin N.
Published: January 2020

l
-Leucine dipeptides can enhance lysyl-transfer ribonucleic acid ligase activity 15- to 20-fold in a mutant of
Escherichia coli
K-12. Evidence indicates the peptides act per se.
Absence of 3′-Terminal Residues from Transfer Ribonucleic Acid of Dormant Spores of
Bacillus megaterium
Authors: Setlow Peter , Primus Grace , Deutscher Murray P.
Published: January 2020

Essentially all (>97%) of the transfer ribonucleic acid (tRNA) in log-phase and sporulating cells of
Bacillus megaterium
contains a complete 3′-cytidyl-cytidyl-adenosine terminus. However, about one-third of the tRNA in the dormant spore lacks the 3′-terminal adenosine 5′-monophosphate (AMP) residue, and some of the adjacent cytosine monophosphate residues are also missing. Examination of specific tRNAs indicated that those specific for isoleucine, leucine, and methionine are missing 30 to 40% of their terminal residue, whereas tRNAs specific for tyrosine lack 88% of the 3′-terminal AMP. Defective spore tRNA is not degraded during germination, but the missing residues are added back in the first minutes of the process. The enzyme catalyzing the addition reaction, tRNA nucleotidyltransferase, is present in the dormant spore at a level similar to that found in the vegetative cell.
Mapping of the Structural Genes of the Three Aspartokinases and of the Two Homoserine Dehydrogenases of
Escherichia coli
K-12
Authors: Thèze J. , Margarita D. , Cohen G. N. , Borne F. , Patte J. C.
Published: January 2020

Mutants requiring threonine plus methionine (or homoserine), or threonine plus methionine plus diaminopimelate (or homoserine plus diaminopimelate) have been isolated from strains possessing only one of the three isofunctional aspartokinases. They have been classified in several groups according to their enzymatic defects. Their mapping is described. Several regions of the chromosome are concerned:
thrA
(aspartokinase I-homoserine dehydrogenase I) is mapped in the same region as
thrB
and
thrC
(0 min).
lysC
(aspartokinase III) is mapped at 80 min, far from the other genes coding for diaminopimelate synthesis.
metLM
(aspartokinase II-homoserine dehydrogenase II) lies at 78 min closely linked to
metB, metJ
, and
metF
.
Effect of
l
-Asparagine on Growth of
Mycobacterium tuberculosis
and on Utilization of Other Amino Acids
Authors: Lyon Richard H. , Hali Wendell H. , Costas-Martinez Carlos
Published: January 2020

l
-Asparagine controls the utilization of other amino acids by
Mycobacterium tuberculosis
(H37Ra) in aerated, liquid synthetic media. In a mixture containing asparagine and either
l
-alanine or
l
-glutamic acid, amino acid utilization is diphasic, with asparagine being utilized first. Short-term growth rates and cell yields are diminished and mimic those seen with asparagine alone. Catabolite repression is the probable regulatory mechanism responsible for this effect of asparagine. In contrast, in the presence of aspartic acid, asparagine stimulates growth and increases utilization of aspartic acid.
Transport Systems for
l
-Methionine in
Escherichia coli
Authors: Kadner Robert J.
Published: January 2020

The transport of
l
-methionine into cells of
Escherichia coli
is described. The transported methionine undergoes a fairly rapid conversion to other cellular metabolites, primarily polyamines, but within 2 min, at least 65% of the intracellular label remains as methionine. The uptake process, which is temperature dependent, allows the accumulation of methionine against a concentration gradient. The dependence of the initial rate of uptake on the extracellular substrate concentration indicates the presence of multiple transport systems, whose kinetic behavior can be approximated by two systems, one with

K
T

= 7.5 × 10
−8
M and

V
T

= 200 pmol per μliter of cell water per min, and the other with

K
T

= 40 × 10
−6
M and

V
T

= 1,550 pmol per μliter per min. Both systems are highly specific for
l
-methionine. Methionine derivatives substituted on the amino or carboxyl group were somewhat effective as inhibitors of
l
-methionine uptake, whereas
d
-methionine, ethionine, or other amino acids were poorly inhibitory, if at all. The uptake process is dependent on metabolic energy, but apparently this energy can be derived either from glycolysis or from oxidative phosphorylation. Efflux of methionine was demonstrable, and both the influx and efflux process were susceptible to inhibition by
N
-ethylmaleimide. The intracellular pool of
l
-methionine was estimated to be 0.1 to 0.3 mM. The transport in two mutant strains defective in methionine uptake (
metD
and
metP
) showed that the high-affinity transport system was lost, whereas the low-affinity system remained more or less intact.
Role for Free Isoleucine or Glycyl-Leucine in the Repression of Threonine Deaminase in
Escherichia coli
Authors: Wasmuth John J. , Umbarger H. E.
Published: January 2020

In
Escherichia coli
, the three branched-chain amino acid activating enzymes appear to be essential for multivalent repression of the isoleucine- and valine-forming enzymes. The results of experiments with a mutant, strain CU18, having an altered threonine deaminase, indicate that free isoleucine and some form of threonine deaminase (the product of the
ilvA
gene) are also involved in multivalent repression. This strain exhibits abnormally high derepressibility but normal repressibility of its
ilv
gene products, and its threonine deaminase is inhibited only by high concentrations of isoleucine. In strain CU18, the isoleucine analogue, thiaisoleucine, is incapable of replacing isoleucine in the multivalent repression of the
ilv
genes, whereas the analogue can fully replace the natural amino acid in repression in other strains examined. The dipeptide, glycyl-leucine, which, like isoleucine, is a heterotropic negative effector of threonine deaminase but is not a substrate for isoleucyl-transfer ribonucleic acid synthetase, can completely prevent the accumulation of threonine deaminase-forming potential during isoleucine starvation in strains with normal threonine deaminases. It can not, however, prevent such accumulation in strain CU18 or in other strains in which threonine deaminase is insensitive to any concentration of isoleucine.
Changes in Menaquinone Concentration During Growth and Early Sporulation in
Bacillus subtilis
Authors: Farrand S. K. , Taber H. W.
Published: January 2020

In two strains of
Bacillus subtilis
, menaquinone-7 has been shown to reach maximal cellular concentrations during early stationary phase. These concentration changes closely parallel the previously reported concentration changes in the cytochromes.
Multiplicity of Isoleucine, Leucine, and Valine Transport Systems in
Escherichia coli
K-12
Authors: Guardiola John , De Felice Maurilio , Klopotowski Tadeusz , Iaccarino Maurizio
Published: January 2020

The kinetics of isoleucine, leucine, and valine transport in
Escherichia coli
K-12 has been analyzed as a function of substrate concentration. Such analysis permits an operational definition of several transport systems having different affinities for their substrates. The identification of these transport systems was made possible by experiments on specific mutants whose isolation and characterization is described elsewhere. The transport process with highest affinity was called the “very-high-affinity”process. Isoleucine, leucine, and valine are substrates of this transport process and their apparent

K
m

values are either 10
−8
, 2 × 10
−8
, or 10
−7
M, respectively. Methionine, threonine, and alanine inhibit this transport process, probably because they are also substrates. The very-high-affinity transport process is absent when bacteria are grown in the presence of methionine, and this is due to a specific repression. Methionine and alanine were also found to affect the pool size of isoleucine and valine. Another transport process is the “high-affinity” process. Isoleucine, leucine, and valine are substrates of this transport process, and their apparent

K
m

value is 2 × 10
−6
M for all three. Methionine and alanine cause very little or no inhibition, whereas threonine appears to be a weak inhibitor. Several structural analogues of the branched-chain amino acids inhibit the very-high-affinity or the high-affinity transport process in a specific way, and this confirms their existence as two separate entities. Three different “low-affinity” transport processes, each specific for either isoleucine or leucine or valine, show apparent

K
m

values of 0.5 × 10
−4
M. These transport processes show a very high substrate specificity since no inhibitor was found among other amino acids or among many branched-chain amino acid precursors or analogues tried. The evolutionary significance of the observed redundancy of transport systems is discussed.
Suppression of Glutamic Acid Codons by Mutant Glycine Transfer Ribonucleic Acid
Authors: Murgola E. J. , Yanofsky C.
Published: January 2020

In previous mutational studies with mutant
trpA46
(Gly [GGA] → Glu [GAA] at position 211 of the tryptophan synthetase alpha chain) of
Escherichia coli
, no missense suppressors were detected. Such suppressors have now been obtained by single mutations in
gly Vins
, the structural gene for a GGA/G-reading, mutationally altered form of
gly V
transfer ribonucleic acid (tRNA) (tRNA
Gly
which reads GGU/C). A
trpA46
strain containing the
gly Vins
alteration was mutagenized with hydroxylamine, and suppressor mutations were detected in the prototrophs obtained. Eighteen independent suppressors were examined and shown to have alterations which map in the
gly V
region. Chromatography of the glycyl-tRNAs of one suppressed mutant on a benzoylated diethylaminoethyl-cellulose column revealed an alteration in the tRNA
ins
Gly
peak. The
trpA46
suppressor mutation thus appears to involve a change of tRNA
ins
Gly
from a GGA/G (Gly) reader to a GAA (Glu) reader. Since this suppressor presumably retains the “wobble” pairing of
gly Vins
tRNA, it was used to select the conversion of GAU (Asp211) to GAG (Glu211) in the alpha chain.
supD
(serine-inserting amber suppressor) was then used to obtain the conversion of GAG (Glu211) to UAG211. Missense revertants of
trpA
(UAG211) are being isolated as a means of introducing new codons which can be used in the selection of additional missense suppressors.
Isolation of Specialized Transducing Bacteriophages for Gluconate 6-Phosphate Dehydrogenase (gnd) ofEscherichia coli
Authors: Wolf Richard E. , Fraenkel D. G.
Published: January 2020

Specialized transducing phages for gluconate 6-phosphate dehydrogenase (gnd), a constitutive enzyme inEscherichia coli, have been isolated using a method previously described for other genes. Thegnd-hisregion, carried on an F′ episome, was first transposed totonB. Rare phages carryinggndwere selected, by transduction, from φ80 lysogens of these strains; one phage also carriedhis(φ80gndhis). From the transductants, high-frequency transducing lysates were obtained; low multiplicity of infection then yielded defective lysogens.tonBdeletion analysis of the φ80dgndhislysogen shows the order of genes in the prophage to beimm80...hisOGD...gnd;according to a marker rescue experiment most phage late genes have been replaced by bacterial deoxyribonucleic acid. A heat-inducible, lysis-defective λ-φ80 hybrid derivative of φ80dgndhishas been prepared.
Properties of Mutants in Galactose Taxis and Transport
Authors: Ordal George W. , Adler Julius
Published: January 2020

β-Methylgalactoside (
mgl
) permease mutants of
Escherichia coli
, which are defective in three genes,
mglA, mglB
, and
mglC
, were assayed for galactose taxis and galactose transport. The
mglB
product is the galactose-binding protein. Previous evidence, supported by our new findings, shows that the galactose-binding protein is the recognition component for galactose taxis as well as for galactose transport. Most mutants defective in
mglB
showed strong effects on both chemotaxis and transport; however, a couple showed effects chiefly on one process or the other, thus allowing a separation of chemotaxis and transport. The
mglA
and
mglC
products have not yet been identified, but they must be components of the galactose transport machinery since mutants defective in
mglA
or
mglC
, or both, showed strongly reduced transport. Although some of these mutants showed little chemotaxis, most gave close to wild-type chemotactic responses. Thus, transport is not required for galactose taxis. The bacteria detect changes in the fraction of binding protein associated with galactose, not changes in the rate of transport.
Alterations in the Outer Membrane of the Cell Envelope of Heptose-Deficient Mutants of
Escherichia coli
Authors: Koplow Jane , Goldfine Howard
Published: January 2020

The composition of the cell envelope of a heptose-deficient lipopolysaccharide mutant of
Escherichia coli
, GR467, was studied after fractionation into its outer and cytoplasmic membrane components by means of sucrose density gradient centrifugation. The outer membrane of GR467 had a lower density than that of its parent strain, CR34. Analysis of the fractionated membranes of GR467 indicated that the phospholipid-to-protein ratio had increased 2.4-fold in the outer membrane. The ratio in the mutant cytoplasmic membrane was also increased, although to a lesser extent. By employing a third parameter, the lipid A content of the outer membrane, it was found that the observed phospholipid-to-protein change in the outer membrane was due predominantly to a decrease in the relative amount of protein. This decrease in protein was particularly significant, since it was concomitant with a 68% decrease in the lipid A recovered in the outer membrane of GR467 relative to the lipid A recovered in the outer membrane of CR34. Similar findings were observed in a second heptose-deficient mutant of
E. coli
, RC-59. The apparent protein deficiency in GR467 was further studied by subjecting solubilized envelope proteins to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was found that major envelope proteins which were localized in the outer membrane were greatly diminished in GR467. Two revertants of GR467 with the wild-type amounts of heptose had wild-type relative levels of protein in their outer membranes. A partial heptose revertant had a relative level of protein in its outer membrane between those of the mutant and wild type.
l
-Amino Acid Dehydrogenases in
Bacillus subtilis
Spores
Authors: Nitta Yukiko , Yasuda Yoko , Tochikubo Kunio , Hachisuka Yoetsu
Published: January 2020

The presence of two kinds of
l
-amino acid dehydrogenase in resting spores of
Bacillus subtilis
was indicated. One of them was
l
-alanine dehydrogenase, which used only
l
-alanine as a substrate, and the other was nonspecific dehydrogenase, which used
l
-valine,
l
-isoleucine,
l
-leucine, and
l
-alanine (slightly) as substrates. Several properties of these dehydrogenases were compared.
β-
d
-Phosphogalactoside Galactohydrolase from
Streptococcus cremoris
HP: Purification and Enzyme Properties
Authors: Johnson K. G. , McDonald I. J.
Published: January 2020

β-
d
-phosphogalactoside galactohydrolase (β-PGal) was isolated and purified from cell-free extracts of
Streptococcus cremoris
HP to apparent homogeneity to gel electrophoresis. Using the chromogenic
o
-nitrophenol-β-
d
-galactopyranoside-6-phosphate as substrate, the purified enzyme exhibited a specific activity of 18.71 U/mg of protein and

K
m

and

V
max

values of 5.88 × 10
−4
M and 23.8 μmol of
o
-nitrophenol liberated per min per mg of protein, respectively.
d
-Galactose-6-phosphate was a weak competitive inhibitor of β-PGal. Activity was relatively heat resistant and was maximal from pH 5.0 to 8.0 and over a temperature range of 45 to 52 C. Dithiothreitol, ethylenediaminetetraacetic acid, and citrate stimulated β-PGal activity, whereas Mg
2+
, Li
1+
, and
p
-hydroxymercuribenzoate were inhibitory. Molecular weight of the enzyme was estimated at 6.76 × 10
4
. Amino acid composition was similar to other β-phosphogalactosidases previously investigated, with the exception that the
S. cremoris
enzyme contains a small amount of half cystine.
Divergent Orientation of Transcription from the Arginine Gene
ECBH
Cluster of
Escherichia coli
Authors: Panchal Chandrakant J. , Bagchee Sourindra N. , Guha Arabinda
Published: January 2020

Ribonucleic acid (RNA) isolated from
Escherichia coli
W3350 (F
−
,
argE
+
C
+
B
+
H
+
), in the absence of
l
-arginine, hybridizes with the separated leftward (
l
) and rightward (
r
) transcribing strands of the arginine transducing phage hφ80
dargE
+
C
+
B
+
H
+
ppc
+
imm

λc
I
857

deoxyribonucleic acid (DNA) with a ratio of 30:70, respectively. In the presence of
l
-arginine and its intermediates,
l
-ornithine and
l
-citrulline, RNA transcriptions from both the strands of the
argECBH
cluster were repressed. The derepressed RNA, when hybridized with the separated strands of hφ80
dargEC
-I
imm
λ
phage DNA (the arginine genes are inversely inserted in this phage), which has a deletion in gene
E
and extends to gene
C
of the
argECBH
cluster, showed no leftward transcription, whereas the rightward transcription was reduced to about 40% of that when the DNA carrying the entire
ECBH
cluster was used for hybridization. The hybridization results thus demonstrate that (i) the regulation of the
argECBH
gene cluster in
E. coli
is under transcriptional control, (ii) the orientation of transcription is divergent, (iii)
E
gene transcribes anticlockwise, whereas the rest of the genes,
C, B
, and
H
, transcribe clockwise, and (iv) the position of the promoter(s) and operator(s) is located between the
E
and
C
genes of the
argECBH
cluster.
Effects of Inhibition and Restoration of Protein Synthesis on the Replication of the R Factor R
ts
1 in
Proteus mirabilis
Authors: Terawaki Yoshiro , Rownd R. , Nakaya Rintaro
Published: January 2020

The effect of inhibition of protein synthesis on the replication of the R factor R
ts
1 in
Proteus mirabilis
was examined by using the technique of CsCl density gradient centrifugation. Only 12% of the copies of R
ts
1 were found to replicate during amino acid starvation, whereas there was a 30% increase in the amount of
P. mirabilis
chromosomal deoxyribonucleic acid (DNA) during the same period. Essentially the same amount of R
ts
1 and host chromosome replication was observed when chloramphenicol was used to inhibit protein synthesis. The replication of R
ts
1 DNA was also examined in experiments in which cultures were starved for amino acids in
14
N-labeled medium and then transferred to
15
N-labeled medium containing the required amino acids. These experiments showed that R
ts
1 replication took place throughout the first generation in
15
N-labeled medium and that each copy of R
ts
1 was replicated one time during the first generation of chromosomal DNA synthesis in
15
N-medium.