bluuebunny/crossref_metadata_2025 huggingface dataset:
Methionine Transport in
Escherichia coli
: Physiological and Genetic Evidence for Two Uptake Systems
Authors: Kadner Robert J. , Watson William J.
Published: January 2020

At least two transport systems serve for the entry of
l
-methionine into
Escherichia coli
. One of these systems has a high affinity for methionine (

K
T

of about 10
−7
M) and is inhibited by methionyl peptides. The other system has a lower affinity (

K
T

of 40 μM). Mutants defective in
metD
lack the high-affinity system and are unable to utilize
d
-methionine or
N
-acetylmethionine as methionine sources. A mutant was isolated which not only lacks the high-affinity system, but which also exhibits decreased activity of the low-affinity system. The transport parameters of the activity remaining in this strain were measured. The energy source for transport appears to be the same as that in the parental strain. The loss of the transport activities was not accompanied by major changes in the methionine pool size or in the rate of methionine excretion or synthesis. The analysis of revertants and transduction crosses supports the conclusion that the strain described is a double mutant in both
metD
(which codes for the high-affinity system) and
metP
(the low-affinity system). The
metD
locus was found to lie between
tonA
(38% co-transduction) and
proA
(9% co-transduction).
Incompatibility Exhibited by Colicin Plasmids E1, E2, and E3 inEscherichia coli
Authors: Inselburg Joseph
Published: January 2020

Escherichia colistrains were made multiply colicinogenic for the colicin plasmids E1, E2, or E3 (Col E1, Col E2, or Col E3, respectively) by both a deoxyribonucleic acid transformation system and bacterial conjugation. The multiply colicinogenic bacteria constructed exhibited an immunity to the colicins produced by all the plasmids they carried and also produced colicins corresponding to all the plasmids they carried. An incompatibility was observed among the plasmids. In doubly colicinogenic cells where the presence of two plasmids was established, Col E2 was lost more frequently than Col E3. In triply colicinogenic cells, Col E1, Col E2, and Col E3 were lost, with Col E3 being lost least frequently. A significant reduction in the acquisition of a conjugationally transferred Col E1 plasmid by cells colicinogenic for Col E1 was demonstrated.
Mapping of a Mutation,
polB100
, Affecting Deoxyribonucleic Acid Polymerase II in
Escherichia coli
K-12
Authors: Campbell Judith L. , Shizuya Hiroaki , Richardson Charles C.
Published: January 2020

Direct assay for deoxyribonucleic acid polymerase II in extracts has been used to screen recombinants for the
polB
allele in Hfr × F
−
crosses, F-ductants in episome transfer, and transductants in generalized transduction by phage P1. The
polB
gene is located at 2 min on the
Escherichia coli
linkage map; it is 39 to 64% co-transducible with
leu
. A mutant,
E. coli polA1 polB100 polC
(ts), deficient in deoxyribonucleic acid polymerases I and II and having a thermolabile deoxyribonucleic acid polymerase III, has been prepared by the P1-mediated cross: P1 (HMS85
polB100
) ×
E. coli
BT1026
polA1 polC
(ts)
leu
−
.
Ultrastructural Study of Pierce's Disease Bacterium in Grape Xylem Tissue
Authors: Mollenhauer Hilton H. , Hopkins Donald L.
Published: January 2020

The rod-shaped rickettsia-like bacteria of Pierce's disease measure about 0.25 to 0.50 μm in diameter and 1.0 to 4.0 μm long. The bacteria have a cell wall consisting of a trilaminar outer membrane and two intermediate low-density layers separated by a dense intermediate layer. A trilaminar cytoplasmic membrane is also present, resulting in a total wall complex thickness of 25 to 40 nm. A periodic infolding of the outer membrane and intermediate layers of the wall give the wall surface a ridged apperance. The ridges appear to go around the long axis of the cell, possibly in the form of spirals. Ribosomes and nuclear regions with easily visible deoxyribonucleic acid strands and clumps are distributed throughout the cytoplasm. Binary fission, during which the cell wall and cytoplasmic membrane folded inward to partition the cell, was observed. In the xylem of infected grapes, the bacteria are either distributed evenly throughout the lumen of the xylem vessel or appressed along the inner surface of the vessel walls in an electron-lucent matrix.
Calcification by
Escherichia coli
Authors: Ennever J. , Vogel J. J. , Streckfuss J. L.
Published: January 2020

Escherichia coli
K-12, grown in a synthetic medium containing metastable calcium phosphate, formed intracellular biological apatite crystals.
Sugar Catabolism in
Aquaspirillum gracile
Authors: Laughon Barbara E. , Krieg Noel R.
Published: January 2020

Aquaspirillum
(
Spirillum
)
gracile
is one of the few spirilla that cause acidification of the medium when cultured with sugars. Acidic reactions have been reported only for
d
-glucose,
d
-galactose, and
l
-arabinose, and the mode of attack of these sugars has not been previously investigated. The soluble portion of extracts of glucose-cultured cells of
A. gracile
ATCC 19624 was found by spectrophotometric methods to contain enzyme activities characteristic of the Entner-Doudoroff and Embden-Meyerhof-Parnas pathways. No activity for 6-phosphogluconate dehydrogenase (EC 1.1.1.44) was detected. Pyridine nucleotide-linked dehydrogenase activities for
l
-arabinose and
d
-galactose (EC 1.1.1.46 and EC 1.1.1.48) occurred in the soluble fraction of cells cultured with either sugar. Glucose-cultured cells contained not only glucokinase (EC 2.7.1.2) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) activities but also glucose dehydrogenase (EC 1.1.1.47) activity. Enzymes capable of oxidizing gluconate were not detectable, but gluconokinase (EC 2.7.1.12) activity was present. Paper chromatographic analysis of the spent culture supernatant media from glucose-cultured cells indicated an accumulation of gluconic acid, and this was confirmed by enzymatic methods. Evidence is presented for the production of
d
-galactonic and
l
-arabonic acids in cultures containing
d
-galactose or
l
-arabinose, respectively.
Genetic Evidence for the Physiological Significance of the
d
-Tagatose 6-Phosphate Pathway of Lactose and
d
-Galactose Degradation in
Staphylococcus aureus
Authors: Bissett Donald L. , Anderson Richard L.
Published: January 2020

Mutants of
Staphylococcus aureus
were isolated which were unable to utilize
d
-galactose or lactose, but which were able to utilize all other carbohydrates tested. Growth of the mutants on a peptone-containing medium was inhibited by
d
-galactose. Of those mutants selected for further study, one (
tagI2
) was missing
d
-galactose 6-phosphate isomerase, one (
tagK3
) was missing
d
-tagatose 6-phosphate kinase, and one (
tagA4
) was missing
d
-tagatose 1, 6-diphosphate aldolase. Each of these mutants accumulated the substrate of the missing enzyme intracellularly. Spontaneous revertants of each of the mutants simultaneously regained their ability to utilize
d
-galactose and lactose, lost their sensitivity to
d
-galactose, regained the missing enzymatic activities, and no longer accumulated intermediates of the
d
-tagatose 6-phosphate pathway. These data support our previous contention that the physiologically significant route for the metabolism of
d
-galactose and the
d
-galactosyl moiety of lactose in
S. aureus
is the
d
-tagatose 6-phosphate pathway. Furthermore, a mutant constitutive for all three enzymes of this pathway was isolated, indicating that the products of the
tagI, tagK
, and
tagA
genes are under common genetic control. This conclusion was supported by the demonstration that
d
-galactose 6-phosphate isomerase,
d
-tagatose 6-phosphate kinase, and
d
-tagatose 1, 6-diphosphate aldolase are coordinately induced in the parental strain.
Inhibition of F
lac
Transfer by the Fin
+
I-Like Plasmid R62
Authors: Willetts N. S. , Paranchych W.
Published: January 2020

F
lac
mutants have been isolated in
Escherichia coli
K-12 which carry dominant mutations resulting in insensitivity to transfer inhibition by the Fin
+
I-like plasmid R62. These mutants were still sensitive to transfer inhibition by the
fin
+
F-like plasmid R100 and, conversely, F
lac
traO
−
and
traP
−
mutants, which are insensitive to R100 inhibition, were still sensitive to R62. The sites of action of the two inhibition systems are therefore different. Furthermore, inhibition by R62, unlike R100, did not require an F-specified product. Like R100, R62 prevented transfer, pilus formation, and surface exclusion and, therefore, probably inhibits expression of the transfer operon
traA
through
traI
. However, R62 was different from R100 in inhibiting transfer of J-independent mutants, indicating that its effect on the transfer operon is probably direct rather than via
traJ
. This is consistent with the different sites of action of the two inhibition systems. None of the F
lac
mutants overproduced pili in the absence of R62, although one mutant differing from those described above showed increased levels of transfer and surface exclusion.
Interrelationship of Repair Mechanisms in Ultraviolet-Irradiated
Escherichia coli
Authors: Moss S. H. , Davies D. J. G.
Published: January 2020

Investigation of the effect of photoreactivation, excision, and recombination repair, individually and in combination, on the survival of ultraviolet-irradiated
Escherichia coli
K-12 mutants has led to a possible explanation of the loss of photoreactivability and of the complex changes in viability observed during liquid-holding. It is suggested that at higher ultraviolet light doses the excision repair mechanism becomes saturated due to overlapping of excised regions on opposite strands of the deoxyribonucleic acid helix. The results also provide support for the existing hypothesis that states that the shape of shouldered survival curves of ultraviolet-irradiated bacteria can be described in terms of the probability of occurrance of overlapping excised regions. Using the data obtained with repair-deficient mutants with closely related genetic makeup, we present a mathematical model that accurately predicts the shape of the observed survival curves and provides an estimate of the number of nucleotides in each fragment of deoxyribonucleic acid removed by the excision repair mechanism.
Incompatibility Reactions of R Plasmids Isolated from
Escherichia coli
of Animal Origin
Authors: Grant Alan J. , Pittard James
Published: January 2020

The incompatibility reactions of a group of 90 R plasmids, isolated from the fecal
Escherichia coli
of calves, pigs, and chickens, have been determined against reference plasmids of the incompatibility groups F
11
, I, N, P, and W. Twenty plasmids belonged to incompatibility groups F
11
, I, N, or P. Forty-nine plasmids were compatible with all of the five reference plasmids. Eight plasmids exhibited marked incompatibility with representatives of two or more of the above groups, whereas two strains showed incompatibility reactions consistent with the coexistence of two compatible plasmids. In addition, 19 plasmids remain untyped because they showed intermediate reactions with one or more reference plasmids.
Pseudomonas putida
Mutants Defective in the Metabolism of the Products of
meta
Fission of Catechol and Its Methyl Analogues
Authors: Wigmore G. J. , Bayly R. C. , Berardino D. Di
Published: January 2020

A selection procedure is described which was used to isolate mutants of
Pseudomonas putida
strain U in the following enzymes of the
meta
-fission pathway of phenol and cresols: hydrolase, tautomerase, and decarboxylase. Strains deficient in the hydrolase are unable to use either
o
- or
m
-cresol as a sole carbon source and were shown to accumulate 2-hydroxy-6-keto-2,4-heptadienoate when incubated in the presence of
o
- or
m
-cresol. When 2-hydroxymuconic semialdehyde (plus nicotinamide adenine dinucleotide, oxidized form) was metabolized by phenol-induced extracts of tautomerase-deficient strains, the enol tautomer of 4-oxalocrotonate accumulated and was then converted slowly to the keto tautomer by a nonenzymatic reaction. Phenol-induced extracts of decarboxylase-deficient strains accumulated the keto tautomer of 4-oxalocrotonate from 2-hydroxymuconic semialdehyde (plus nicotinamide adenine dinucleotide, oxidized form). Strains with an inactive decarboxylase are unable to completely metabolize either phenol or
p
-cresol. Tautomerase-defective strains are unable to grow with
p
-cresol as the sole carbon source and grow only very slowly on phenol.
Spermidine Biosynthesis During Germination and Subsequent Vegetative Growth of
Bacillus megaterium
Spores
Authors: Setlow Peter
Published: January 2020

Spermidine biosynthesis was extremely low early in germination of
Bacillus megaterium
spores and the spermidine level remained constant. Rapid synthesis began after 130 min and thereafter accounted for the increase in spermidine level which began at this time. Biosynthesis was greatly (>84%) diminished by exogenous spermine or spermidine. Arginine and ornithine were both converted efficiently into spermidine, but arginine was the more immediate precursor as shown by isotope competition studies and by the absence of ornithine decarboxylase and the presence of arginine decarboxylase. Exogenous putrescine was not incorporated into spermidine, although it was taken up rapidly and degraded.
Peptidase Mutants of
Salmonella typhimurium
Authors: Miller Charles G. , Mackinnon Karen
Published: January 2020

Six peptidase activities have been distinguished electrophoretically in cell extracts of
Salmonella typhimurium
with the aid of a histochemical stain. The activities can also be partially separated by chromatography on diethylaminoethyl-cellulose. These peptidases show overlapping substrate specificities. Mutants (
pepN
) of the parent strain
leu-485
lacking one of these enzymes (
peptidase N
) were obtained by screening for colonies that do not hydrolyze the chromogenic substrate
l
-alanyl-β-naphthylamide. The absence of this broad-specificity peptidase in
leu-485 pepN
−
mutants allowed the selection of mutants unable to use
l
-leucyl-
l
-alaninamide as a leucine source. These mutants (
leu-485 pepN
−
pepA
−
) lack a broad-specificity peptidase (peptidase A) similar to aminopeptidase I previously described in
Escherichia coli
. Mutants (
pepD
) lacking a dipeptidase (peptidase D) have been isolated from a
leu-485 pepN
−
pepA
−
parent by penicillin selection for mutants unable to use
l
-leucyl-
l
-glycine as a leucine source. Mutants (
pepB
) lacking a fourth peptidase (peptidase B) have been isolated from a
leu-485 pepN
−
pepA
−
pepD
−
strain by penicillin selection for failure to utilize
l
-leucyl-
l
-leucine as a source of leucine. Single recombinants were obtained by transduction for each of the peptidases missing in a
leu-485 pepN
−
pepA
−
pepD
−
pepB
−
strain. The growth response of these recombinants to leucine peptides shows that all of these peptidases can function in the catabolism of peptides and that they display overlapping substrate specificities in vivo.
Biochemical Studies of Two
Bacillus pumilus
Plasmids
Authors: Lovett Paul S. , Bramucci Michael G.
Published: January 2020

Bacillus pumilus
NRS 576 harbored an estimated two copies per chromosome of a covalently closed, circular (CCC) deoxyribonucleic acid (DNA) molecule, the 576 plasmid. The 576 plasmid has a buoyant density of 1.698 g/cm
3
and a molecular weight of about 28 × 10
6
. Plasmid copy number remained about the same in both exponentially growing and stationary-phase cells. Spontaneous variants of NRS 576 that formed spores at an elevated frequency were designated as W mutants. W mutants appeared to have lost the 576 plasmid on the basis of the following: W mutants (38 tested) lacked detectable CCC DNA, and the majority of the plasmid homologous sequences in bulk NRS 576 DNA were absent from bulk W mutant DNA.
B. pumilus
ATCC 7065 harbored at least 10 copies per chromosome of a CCC DNA element, the 7065 plasmid. The 7065 plasmid has a buoyant density of 1.696 g/cm
3
and a molecular weight of about 6 × 10
6
. Although the copy number of the plasmid appeared to remain the same in exponentially growing and stationary-phase cells, an additional CCC form of higher molecular weight was detected in stationary-phase cells.
Properties of the Relaxation Complexes of Supercoiled Deoxyribonucleic Acid and Protein of the R Plasmids R64, R28K, and R6K
Authors: Kupersztoch-Portnoy Yankel M. , Miklos George L. G. , Helinski Donald R.
Published: January 2020

The presence of supercoiled deoxyribonucleic acid in the form of a relaxation complex is described for the antibiotic resistance plasmids R64, R28K, and R6K. The properties of these relaxation complexes indicate that they consist of a covalently closed circular deoxyribonucleic acid molecule associated with an activable, single strand-specific endonuclease.
Residual Thymidine Incorporation in the Presence of Chloramphenicol in Synchronous Cultures of
Escherichia coli
B/r
Authors: Helmstetter Charles E.
Published: January 2020

Escherichia coli
B/r ATCC 12407 which grew synchronously with interdivision times of 45 and 85 min were exposed at intervals to chloramphenicol (200 μg/ml) and [
14
C]thymidine for short or long (residual) periods. The results suggested that the pattern of residual thymidine incorporation in 85-min cells yielded an estimate of the length of the D period rather than the time of initiation of chromosome replication.
Induction of β-Galactosidase in
Lactobacillus plantarum
Authors: Hasan N. , Durr I. F.
Published: January 2020

β-galactosidase (β-galactoside galactohydrolase, EC 3.2.1.23) is inducible in
Lactobacillus plantarum
by
d
-galactose or thiomethyl galactoside, and to a much lesser extent by lactose, isopropyl thiomethyl galactoside, and
d
-fucose. Isopropyl thiomethyl galactoside is a competitive inhibitor of the enzyme with a

K
i

of 4.2 mM. The

K
m

of the crude enzyme for
o
-nitrophenyl β-
d
-galactoside is 0.87 mM. Induction also requires a source of energy and amino acids. Chloramphenicol and actinomycin D inhibited induction.
d
-Glucose,
d
-fructose and to a lesser extent maltose and
d
-mannitol inhibited enzyme synthesis. Methyl-alpha-
d
-glucopyranoside was not inhibitory. Glucose exerts its effect through its ability to exclude galactose or lactose entry into the cell. The uptake of lactose and the metabolism of galactose by preinduced cells is severely inhibited by glucose. But neither galactose nor lactose severely affected the uptake of glucose by preinduced cells. Thus, glucose acts through catabolite inhibition, i.e., transport of inducer rather than repression through transcription or related mechanisms. This is supported by the inability of cyclic nucleotides to relieve the inhibition produced by glucose or to stimulate induction. Furthermore, intracellularly produced glucose did not inhibit enzyme synthesis. Acetate and mevalonate, the precursors of membrane lipids, stimulate induction independently of their effect on growth. Homobiotin partially abolished the acetate effect but did not inhibit induction or growth.
Regulation of Nitrogen Fixation in
Klebsiella pneumoniae
: Evidence for a Role of Glutamine Synthetase as a Regulator of Nitrogenase Synthesis
Authors: Streicher Stanley L. , Shanmugam K. T. , Ausubel Frederick , Morandi Carlo , Goldberg Richard B.
Published: January 2020

Mutations causing constitutive synthesis of glutamine synthetase (GlnC
−
phenotype) were transferred from
Klebsiella aerogenes
into
Klebsiella pneumoniae
by P1-mediated transduction. Such GlnC
−
strains of
K. pneumoniae
have constitutive levels of glutamine synthetase. Two of three GlnC
−
strains of
K. pneumoniae
studied, each containing independently isolated mutations that confer the GlnC
−
phenotype, continue to synthesize nitrogenase in the presence of NH
4
+
. One strain, KP5069, produces 30% as much nitrogenase when grown in the presence of 15 mM NH
4
+
as in its absence. The GlnC
−
phenotype allows the synthesis of nitrogenase to continue under conditions that completely repress nitrogenase synthesis in the wild-type strain. Glutamine auxotrophs of
K. pneumoniae
, that do not produce catalytically active glutamine synthetase, are unable to synthesize nitrogenase during nitrogen limited growth. Complementation of
K. pneumoniae
Gln
−
strains by an
Escherichia coli
episome (F′133) simultaneously restores glutamine synthetase activity and the ability to synthesize nitrogenase. These results indicate a role for glutamine synthetase as a positive control element for nitrogen fixation in
K. pneumoniae
.
Regulation of Bacterial Cell Walls: Turnover of Cell Wall in
Staphylococcus aureus
Authors: Wong W. , Young F. E. , Chatterjee A. N.
Published: January 2020

The cell wall of
Staphylococcus aureus
was shown to undergo turnover during exponential growth. The rate of turnover, about 15% per generation, was identical for both cell wall polymers, peptidoglycan and teichoic acid. Both the old and newly synthesized wall material appeared to undergo turnover at similar rates. The rate of turnover followed first-order kinetics until more than 90% of the original wall was lost. Cell wall turnover was completely blocked under conditions of unbalanced synthesis known to inhibit cellular autolysis, e.g., addition of chloramphenicol. Cell wall turnover was shown to occur in a number of different strains of
S. aureus
and appears to be widely distributed in this species.
Antigenic Difference Between Polar Monotrichous and Peritrichous Flagella of
Vibrio parahaemolyticus
Authors: Shinoda Sumio , Honda Takeshi , Takeda Yoshifumi , Miwatani Toshio
Published: January 2020

Polar monotrichous and peritrichous flagella of
Vibrio parahaemolyticus
were isolated and purified separately. On hydroxylapatite column chromatography, the flagellins of polar monotrichous flagella were eluted with a higher concentration of phosphate than those of peritrichous flagella. Gel diffusion tests showed an antigenic difference between the flagellins of polar monotrichous and peritrichous flagella. Electron microscope observations on cells stained with ferritin-conjugated antibodies demonstrated that polar monotrichous and peritrichous flagella reacted specifically with antimonotrichous flagellin and antiperitrichous flagellin antisera, respectively.
Action of Lysozyme on Penicillin-Induced Filaments of
Proteus vulgaris
Authors: Fleck Jacqueline , Martin Jean-Pierre , Mock Michèle
Published: January 2020

Penicillin-induced filaments of
Proteus vulgaris
P 18 had a seemingly unaltered cell envelope. Lysozyme, however, reduced the wall part of these filaments into a three-layered structure and caused transformation into spheroplasts. Although cross walls and membrane septa were absent in the filaments, most of the lysozyme-induced spheroplasts remained attached to each other.
Partial Purification and Properties of
d
-Glucosamine 6-Phosphate
N
-Acetyltransferase from Zoospores of
Blastocladiella emersonii
Authors: Giddings Thomas H. , Cantino Edward C.
Published: January 2020

A
d
-glucosamine 6-phosphate
N
-acetyltransferase from
Blastocladiella emersonii
zoospores was partially purified to a specific activity of 2.41 IU per mg of protein. Its pH optimum was 8.05 and its

K
m

values were 2.4 × 10
−4
M
d
-glucosamine 6-phosphate and 0.38 × 10
−4
M Na
3
S-acetyl coenzyme A.
Metabolism of
n
-Butane and 2-Butanone by
Mycobacterium vaccae
Authors: Phillips W. E. , Perry J. J.
Published: January 2020

n
-Butane was metabolized in
Mycobacterium vaccae
(JOB5) via terminal oxidation. This organism metabolized 2-butanone through propionate (or propionyl coenzyme A). Subterminal oxidation in
M. vaccae
was apparently limited to propane.
Incorporation of
d
-Alanine into the Membrane of
Streptococcus pyogenes
and Its Stabilized L-Form
Authors: Chevion Mordechai , Panos Charles , Linzer Rosemary , Neuhaus Francis C.
Published: January 2020

A principal aim of this study was to explain our earlier finding of a lack of
d
-alanine in the glycerol teichoic acid from the membrane of a stabilized L-form of
Streptococcus pyogenes
(B. M. Slabyj and C. Panos, 1973. J. Bacteriol.
114:
934-942). It was found that the incorporation of
d
-alanine into the membrane teichoic acid of
S. pyogenes
requires either supernatant fraction or two enzymes from supernatant fraction, stimulator (
d
-alanine activating enzyme) and
d
-alanine:membrane acceptor ligase, plus membrane fragments, ATP and Mg
2+
. A similar system from the L-form is inoperative. Also, no incorporation is observed with L-form or coccal supernatant fractions when L-form membranes are used. However,
d
-alanine incorporation is observed when L-form enzymes are used with membrane fragments from the parental streptococcus. Thus, the L-form possesses the required soluble components for
d
-alanine incorporation but the L-form membrane cannot function as acceptor even though it contains
d
-alanine-deficient membrane teichoic acid. These results suggest that a defect has occurred in the membrane of this stabilized L-form for
d
-alanine incorporation into membrane teichoic acid.
Evolution of a New Gene Substituting for the
leuD
Gene of
Salmonella typhimurium
: Origin and Nature of
supQ
and
newD
Mutations
Authors: Kemper Jost
Published: January 2020

The second specific enzyme in the biosynthesis of leucine, α-isopropylmalate isomerase, is coded for by two genes,
leuC
and
leuD
. Leucine auxotrophs carrying mutations in the
leuD
gene (including deletions of the entire
leuD
gene) revert to leucine prototrophy by secondary mutations at the locus
supQ
, which is located in the proline region of the chromosome. The mechanism of the
supQ
function is explained by the following model. The
supQ
gene and an additional gene,
newD
, code for two different subunits of a multimeric enzyme, whose normal function is yet to be determined. The
newD
gene protein is able, without genetic alterations, to form an active complex with the
leuC
protein, thus replacing the nonfunctional or missing
leuD
protein and restoring leucine prototrophy. The
newD
protein has, however, a higher affinity for the
supQ
protein than for the
leuC
protein; therefore, mutations in the
supQ
gene are needed to make sufficient amounts of the
newD
protein available. The following gene order has been established:
gpt-proB-proA-ataA-supQ-newD
. Different
supQ
mutations have been identified, i.e., insertion in the
supQ
gene, point mutations, and deletions of various extent. Some deletions remove the P22 phage attachment site
ataA
. Other
supQ
deletions are simultaneously Pro
−
, because they extend into the
proA
or
proA
and
proB
genes; some extend even further, i.e., into the
gpt
gene (guanine phosphoribosyl transferase). Mutations in the
newD
gene caused renewed leucine auxotrophy in
leuD supQ
mutant strains. One
newD
mutation causes a temperature-sensitive Leu
+
phenotype. Alternate models for the
supQ-newD
interactions are discussed.
Relationship Between Lysogeny, Spontaneous Induction, and Transformation Efficiencies in
Bacillus subtilis
Authors: Garro Anthony J. , Law Ming-Fan
Published: January 2020

The low transformation efficiency of
Bacillus subtilis
168 lysogenic for phages ø105 or SPO2 is shown to result from the induction of lytic phage replication in competent cells. Lysogenic competent cells have a higher rate of spontaneous prophage induction than noncompetent cells. Mutants of ø105 and SPO2 which form lysogens resistant to spontaneous induction were isolated, and these lysogens exhibited higher transformation levels than those formed by wild-type phage. These results suggest that the physiological state of competence in
B. subtilis
promotes prophage derepression leading to cell death and the loss of potential transformants.
Salmonella typhimurium Mutants Defective in Cytidine Monophosphate Kinase (cmk)
Authors: Beck Christoph F. , Neuhard Jan , Thomassen Elisabeth , Ingraham John L. , Kleker Elizabeth
Published: January 2020

Mutants of
Salmonella typhimurium
defective in cytidine 5′-monophosphate (CMP) kinase (
cmk
) have been isolated. The mutants also lack the ability to phosphorylate 2′-deoxyCMP, indicating that one enzyme is responsible for the phosphorylation of both CMP and deoxyCMP to the corresponding diphosphates. In glucose minimal medium the mutants grow at the same rate as the parental strain; however, they excrete large quantities of pyrimidines into the growth medium. Cytidine but not deoxycytidine has been identified among the excreted products. The mutant phenotype suggests that the physiological role of CMP kinase is that of rephosphorylating CMP arising from the breakdown of messenger ribonucleic acid. This proposed role of CMP kinase is supported by the fact that a
cmk
−
mutant is much more sensitive to any partial impairment of cytidine 5′-triphosphate synthetase than is the
cmk
+
parent strain. The gene
cmk
has been located on the
Salmonella
chromosome at 38.5 min. No markers which can be cotransduced with
cmk
by phage P22 have been found.
Regulation of Synthesis of the Branched-Chain Amino Acids and Cognate Aminoacyl-Transfer Ribonucleic Acid Synthetases of
Escherichia coli
: a Common Regulatory Element
Authors: Jackson Julius , Williams L. S. , Umbarger H. E.
Published: January 2020

Regulation of isoleucine, valine, and leucine biosynthesis and isoleucyl-, valyl-, and leucyl-transfer ribonucleic acid (tRNA) synthetase formation was examined in two mutant strains of
Escherichia coli
. One mutant was selected for growth resistance to the isoleucine analogue, ketomycin, and the other was selected for growth resistance to both trifluoroleucine and valine. Control of the synthesis of the branched-chain amino acids by repression was altered in both of these mutants. They also exhibited altered control of formation of isoleucyl-tRNA synthetase (EC 6.1.15, isoleucine:sRNA ligase, AMP), valyl-tRNA synthetase (EC 6.1.1.9, valine:sRNA ligase, AMP), and leucyl-tRNA synthetase (EC 6.1.1.4, leucine:sRNA ligase, AMP). These results suggest the existence of a common element for the control of these two classes of enzymes in
Escherichia coli
.
Purification and Characterization of Axial Filaments from
Treponema phagedenis
Biotype
reiterii
(the Reiter Treponeme)
Authors: Bharier Michael , Allis David
Published: January 2020

Axial filaments have been purified from
Treponema phagedenis
biotype
reiterii
(the Reiter treponeme) and partially characterized chemically. The preparations consist largely of protein but also contain small amounts of hexose (3%). Filaments dissociate to subunits in acid, alkali, urea, guanidine, and various detergents. Amino acid analyses show an overall resemblance to other spirochetal axial filaments and to bacterial flagella. Dissociated filaments migrate as a single band upon acrylamide gel electrophoresis at pH 4.3 (in 4 M urea and 10
3
M ethylenediaminetetraacetate) and at pH 12, but in sodium dodecyl sulfate gels, three bands are obtained under a wide variety of conditions. Two of these bands migrate very close together, with molecular weights of 33,000 ± 500. The other band has a molecular weight of 36,500 ± 500. Analysis of axial filaments by the dansyl chloride method yields both methionine and glutamic acid as amino terminal end groups. Sedimentation equilibrium measurements on dissociated axial filaments in 7 M guanidine hydrochloride yield plots of log C against ϰ
2
which vary with the speed and initial protein concentration used. Molecular weight values calculated from these plots are consistent with a model in which axial filament subunits are heterogeneous with respect to molecular weight in the approximate range of 32,000 to 36,000.
Developmental Modulation of Deoxyribonucleic Acid-Binding Proteins of
Bacillus subtilis
During Sporulation Stages
Authors: Brehm Sylvia P. , Le Hegarat Françoise , Hoch James A.
Published: January 2020

The isolation of deoxyribonucleic acid (DNA)-binding proteins from various stages of growth and sporulation of
Bacillus subtilis
is described. After adsorption and elution from phosphocellulose, the proteins were fractionated according to their ability to adsorb to denatured calf thymus DNA-cellulose or native
B. subtilis
DNA-cellulose. The proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and purification was monitored by a nitrocellulose filter binding assay. Approximately 1% of the proteins in the crude extract adsorbed to denatured calf thymus DNA-cellulose and 0.1% adsorbed to native
B. subtilis
DNA-cellulose. Each class of proteins varied qualitatively and quantitatively as sporulation proceeded. Several proteins from the exponential phase of growth that bound to denatured DNA were lost by T
0
, whereas at T
5
new polypeptides appeared. Fewer changes in the profile of proteins with affinity for native DNA were observed between exponential phase and T
0
; however, the dominant species in these eluates were clearly different.
Isolation of a metabolite capable of differentially supporting the growth of nicotinamide adenine dinucleotide auxotrophs of Escherichia coli
Authors: Chen J L , Tritz G J
Published: January 2020

A compound, isolated from the culture fluid of a nadC auxotroph of Escherichia coli grown in a minimal medium, supports the growth of both a nadA and a nadB mutant. This metabolite exhibits an ultraviolet light absorption spectrum and a mass spectrum, different from quinolinic acid. This compound may be the precursor of quinolinic acid, an intermediate in the biosynthesis of nicotinamide adenosine dinucleotide.
Genetic modification of substrate specificity of hypoxanthine phosphoribosyltransferase in Salmonella typhimurium
Authors: Benson C E , Gots J S
Published: January 2020

Salmonella typhimurium strain GP660 (proAB-gpt deletion, purE) lacks guanine phosphoribosyltransferase and hence cannot utilize guanine as a purine source and is resistant to inhibition by 8-azaguanine. Strain GP660 was mutagenized and a derivative strain (GP36) was isolated for utilization of guanine and hypoxanthine, but not xanthine, as purine sources. This alteration was designated sug. The strain was then sensitive to inhibition by 8-azaguanine. Column chromatographic analysis revealed the altered phosphoribosyltransferase peaks for both hypoxanthine and guanine to be located together, in the same position as hypoxanthine phosphoribosyltransferase (hpt gene product) of the wild-type strain. Genetic analysis showed the sug mutation to be allelic with hpt. Therefore sug represented a modification of the substrate specificity of the hpt gene product.
Characterization of lipopolysaccharides from Escherichia coli K-12 mutants
Authors: Boman H G , Monner D A
Published: January 2020

Chemical analyses of the carbohydrate composition of lipopolysaccharides (LPS) from a number of LPS mutants were used to propose a schematic composition for the LPS from Escherichia coli K-12. The formula contains four regions: the first consists of lipid A, ketodeoxyoctonoic acid, and a phosphorous component; the second contains only heptose; the third only glucose; and the fourth additional glucose, galactose, and rhamnose. LPS from E. coli B may have a similar composition but lacks the galactose and rhamnose units. A set of LPS-specific bacteriophages were used for comparing three mutants of Salmonella with a number of LPS mutants of E. coli K-12. The results confirm that there are basic similarities in the first and second regions of the LPS structure; they also support the four region divisions of the LPS formula. Paper chromatography was used for characterization of 32-P-labeled LPS from different strains of E. coli and Salmonella. The Rf values for LPS varied from 0.27 to 0.75 depending on the amounts of carbohydrates in the molecule. LPS from all strains studied was homogenous except for strain D31 which produced two types of LPS. Mild acid hydrolysis of labeled LPS liberated lipid A and two other components with phosphate, one of which was assigned to the first region. It is suggested that paper chromatography can be used in biosynthetic studies concerning regions 2 to 4.
Transformation of leucine and rifampin traits in Neisseria gonorrhoeae with deoxyribonucleic acid from homologous and heterologous origins
Authors: Wood D O , Brownell G H
Published: January 2020

A leucine-requiring, rifampin-sensitive strain of Neisseria gonorrhoeae was transformed to a leucine-nonrequiring, rifampin-resistant phenotype with deoxyribonucleic acid (DNA) obtained from both N. meningitidis and N. gonorrhoeae. The transforming efficiency of the meningococcal DNA was about 10- to 100-fold less than that of the homologous gonococcal DNA. A chemically defined medium that would support growth of most gonococcal isolates was used as a complete medium. A minimal medium was used for selection of Leu+ transformants. N-methyl-N'-nitro-N-nitrosoguanidine was used as a mutagen for isolating leucine prototrophs from leucine-requiring isolates of N. gonorrohoeae.
Suppression of initiation-negative strains of Escherichia coli by integration of the sex factor F
Authors: Tresguerres E F , Nandadasa H G , Pritchard R H
Published: January 2020

Data are presented suggesting that the most critical factor determining whether an Hfr dnaAts strain can synthesize deoxyribonucleic acid and form colonies at temperatures that are nonpermissive for corresponding F- strains is neither the site of insertion of F nor the presence of additional mutations in the F particle or the chromosome; it is whether the particle is capable of autonomous replication at the temperature used. Consequently, suppression of the DnaA phenotype in Hfr strains occurs at 40 C but not, in most of them, at 42 C without the occurrence of additional mutations. The site of insertion of F may also be important since it is shown that in one Hfr dnaA strain partial suppression does occur at 42 C. In addition, it is shown that strains exhibiting suppression by integration of F at 40 C on minimal agar plates do not do so at this temperature on nutrient agar plates.
Positive selection of general amino acid permease mutants in Saccharomyces cerevisiae
Authors: Rytka J
Published: January 2020

It was found that D-stereoisomers of natural amino acids inhibit the growth of Saccharomyces cerevisiae cells. Kinetic and genetic evidence showed that d-amino acids enter the cell by the general amino acid permease. Two classes of S. cerevisiae mutants resistant to d-amino acids were isolated. One class of mutants appeared to be defective in the general amino acid permease specified by the gene gap. In the second class, the activity of general amino acid permease was affected by ammonium ions. Mutants of the second class were isolated in a yeast strain with the general amino acid permease insensitive to the presence of ammonium ions in culture media. The mutation affecting the permease, amc, occurred in a locus unlinked to gap.
Relationship of macromolecular synthesis to competence induction in a group H streptococcus
Authors: Horne D S , Perry D
Published: January 2020

Group H streptococcus strain Wicky, which was induced to competence for genetic transformation with competence factor (CF) derived from a related strain, displayed reduced rates of ribonucleic acid (RNA) and peptidoglycan synthesis. Pulse-labeling studies revealed that the inhibition of both RNA and peptidoglycan synthesis was maximal at the peak of competence and decreased as competence declined. These studies indicated that competence induction had only a slight effect on the rate of protein synthesis. Trypsin inactivation of CF prevented the reductions in synthesis normally elicited by CF preparations. If the addition of trypsin was delayed until 5 min after the addition of CF, competence induction and decreased synthesis of RNA and peptidoglycan were again apparent. Thus, the alterations in the synthesis of these macromolecules appeared to be related to the induction of competence. Further studies indicated that the apparent reductions in biosynthesis were not caused by decreased uptake of the labeled precursors by intact Wicky cells. In addition, these effects were probably not the result of turnover of macromolecules induced by CF. The lack of turnover of labeled peptidoglycan suggested that competence induction may not involve an autolysin.
Isolation and characterization of catabolite-resistant mutants in the D-serine deaminase system of Escherichia coli K-12
Authors: Bloom F R
Published: January 2020

Two classes of D-serine deaminase (Dsdase)-specific secondary mutants of Escherichia coli K-12 were isolated from a Dsdase low constitutive nonhyperinducible mutant as types which could grow in the presence of both D-serine and glucose. These strains contain cis dominant, nonsuppressible mutations in the dsdO (operator-initiator) region. In the first class of mutants (e.g., FB4010), Dsdase synthesis is completely insensitive to catabolite repression, and synthesis occurs at a high constitutive rate in the absence of cyclic adenosine 5'-monophosphate. In the second class (e.g., FB4005), Dsdase synthesis is partially insensitive to catabolite repression, and catabolite repression is reversed by the addition of cyclic adenosine 5'-monophosphate. Dsdase synthesis in strain FB4005 is partially independent of the cyclic adenosine 5'-monophosphate binding protein, as constitutive synthesis is reduced only 65% (relative to the cap+ strain) in strains unable to synthesize the cyclic adenosine 5'-monophosphate binding protein. Surprisingly, the constitutive rate of Dsdase synthesis is fourfold higher in all mutants of both classes than in the parent, indicating a close interrelationship between the sites of response to induction and catabolite repression.
Polyphosphate levels in nongrowing cells of Saccharomyces mellis as determined by magnesium ion and the phenomenon of "Uberkompensation"
Authors: Weimberg R
Published: January 2020

Magnesium ion enhances the maximum amount of polyphosphate that resting phosphate-starved cells of Saccharomyces mellis can store by increasing the length of time the cells will continue assimilating phosphate. The divalent cation has no effect on the rate of formation of polymer. As much as 12 times more polyphosphate is formed in cells incubated in reaction mixtures containing 0.3 M MgCl2 than in the absence of Mg2+. Potassium ion also has an influence on the amount of polyphosphate that phosphate-starved cells can accumulate but the degree of stimulation is not very large. Mg2+ and K+ have no effect on polyphosphate formation or storage in phosphate-satiated cells. Apparently, then, there are two systems for polyphosphate accumulation in S. mellis. Each system is stable in nondividing cells. The one present in phosphate-starved cells seems to be repressible by growth of the organism in media containing orthophosphate. The shift from the derepressed state to the repressed state, or vice versa, occurs only in exponentially dividing cells in appropriate media with 100% of the cells in the new physiological state by the time the cell mass has doubled. It is suggested that the word to describe the phenomenon of the accumulation of higher amounts of polyphosphate in phosphate-starved cells than the steady-state level of phosphate-satiated cells be changed from "uberkompensation" to "magnesium ubertriebung," or "magnesium enhancement."
Utilization of nucleoside monophosphates per Se for intraperiplasmic growth of Bdellovibrio bacteriovorus
Authors: Rittenberg S C , Langley D
Published: January 2020

During growth of Bdellovibrio bacteriovorus on Escherichia coli, there was a marked preferential use of E. coli phosphorus over exogenous orthophosphate even though the latter permeated into the intraperiplasmic space where the bdellovibrio was growing. This preferential use occurred to an equal extent for lipid phosphorus and nucleic acid phosphorus. Exogenous thymidine-5'-monophosphate competed effectively with [3H]thymine residues of E. coli as a precursor for bdellovibrio deoxyribonucleic acid; exogenous thymidine competed less effectively and thymine and uridine not at all. A mixture of exogenous nucleoside-5'-monophosphates equilibrated effectively with E. coli phosphorus as a phosphorus source for B. bacteriovorus; the nucleotide phosphorus entered preferentially into bdellovibrio nucleic acids. A comparable mixture of exogenous nucleosides plus orthophosphate had only a small effect on utilization of E. coli phosphorus by B. bacteriovorus, as did orthophosphate alone. A mixture of exogenous deoxyriboside monophosphates equilibrium effectively with E. coli phosphorus as a phosphorus source for bdellovibrio growth; the phosphorus from this source entered preferentially into deoxyribonucleic acid. These data show that nucleoside monophosphates derived from the substrate organism are utilized directly for n-cleic acid biosynthesis by B. bacteriovorus growing intraperiplasmically. As a consequence, the phosphate ester bonds preexisting in the nucleic acids of the substrate organism are conserved by the bdellovibrio, presumably lessening its energy requirement for intraperiplasmic growth. The data also suggest, but do not prove, that the phosphate ester bonds of phospholipids are also conserved.
Incorporation of long-chain fatty acids of the substrate organism by Bdellovibrio bacteriovorus during intraperiplasmic growth
Authors: Kuenen J G , Rittenberg S C
Published: January 2020

Data are presented showing that a large proportion of the fatty acids of Bdellovibrio bacteriovorus grown intraperiplasmically are derived unaltered from the fatty acids of its substrate organism. Those fatty acids of the bdellovibrio not homologous with those of the substrate organism are derived mainly by metabolic alteration of preexisting fatty acids in the latter. De novo synthesis from acetate occurs only to a small extent. These characteristics of bdellovibrio physiology are in part responsible for its minimal energy expenditure for intraperiplasmic growth. The data presented also indicate that B. bacteriovorus is capable of hydrogenating unsaturated fatty acids, of beta-oxidation of fatty acids, and of regulating the proportion of saturated and unsaturated fatty acids in the lipids.
Purification and properties of gentisate 1,2-dioxygenase from Moraxella osloensis
Authors: Crawford R L , Hutton S W , Chapman P J
Published: January 2020

Gentisate:oxygen 1,2-oxidoreductase (decyclizing) (EC 1.13.11.4; gentisate 1,2-dioxygenase) from Moraxella osloensis was purified to homogeneity as shown by polyacrylamide gel electrophoresis. The enzyme has a molecular weight of about 154,000 and gives rise to subunits of molecular weight 40,000 in the presence of sodium dodecyl sulfate. Gentisate 1,2-dioxygenase showed broad substrate specificity and attacked a range of halogen- and alkyl-substituted gentisic acids. Maleylpyruvate, the product formed from gentisate, was degraded by cell extracts supplemented with reduced glutathione, but substituted maleylpyruvates were not attacked under these conditions.
Integration of R plasmid Rts1 to the gal region of the Escherichia coli chromosome
Authors: Terawaki Y , Kishi H , Nakaya R
Published: January 2020

An R plasmid Rts1 was integrated into the gal region of the chromosome of Escherichia coli XA-7012 (galE) strain by the directed transposition technique. The integration of the Rts1 genome was confirmed mainly by conjugation studies and also by transduction experiments using phage P1. As a result, it was found that the integrated genome contained genes responsible for kanamycin resistance, conjugal transferability, and for autonomous replication. As reported previously, Rts1 is temperature sensitive in replication and inhibits the growth of the host at nonpermissive temperature. However, although a plasmid derived from the integrated Rts1 genome still demonstrates temperature sensitivity upon transfer and high level of kanamycin resistance, this plasmid no longer displays temperature sensitivity in replication and the inhibitory effect on the host. These results indicate that the temperature sensitivity of replication of Rts1 and its inhibitory effect on the host cell are due to the presence of a gene or gene cluster on the Rts1 genome and that the gene(s) is clearly discriminated from the one responsible for the temperature sensitivity of transfer.