bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Events Accompanying the Fixation of Genetic Information in
Haemophilus
Heterospecific Transformation
Authors: Notani N. K. , Setlow Jane K.
Published: January 2020

Heterospecific transformation between
Haemophilus influenzae
and
H. parainfluenzae
was investigated by isopycnic analysis of deoxyribonucleic acid (DNA) extracts of
3
H-labeled transforming cells that had been exposed to
32
P-labeled, heavy transforming DNA. The density distribution of genetic markers from the resident DNA and from the donor DNA was determined by transformation assay of fractions from CsCl gradients, both species being used as recipients. About 50% of the
32
P atoms in
H. parainfluenzae
donor DNA taken up by
H. influenzae
cells were transferred to resident DNA, and only a small amount of the label was lost under conditions of little cell growth. There was less transfer in the reciprocal cross, and almost half of the donor label was lost. In both crosses, the transferred donor material transformed for the donor marker considerably more efficiently when assayed on the donor species than on the recipient species, indicating that at least some of the associated
32
P atoms are contained in relatively long stretches of donor DNA. When the transformed cultures were incubated under growth conditions, the donor marker associated with recipient DNA transformed the donor species with progressively decreasing efficiency. The data indicate that the low heterospecific transformation between
H. influenzae
and
H. parainfluenzae
may be due partly to events occurring before association of donor and resident DNA but results mostly from events that occur after the association of the two DNA preparations.
Location of the Origin of Transfer of the Sex Factor F
Authors: Willetts N. S.
Published: January 2020

The location of the origin of transfer on the map of F
lac
has been determined by two different techniques. The first showed that no transfer cistrons were transferred early by a transposition Hfr strain with a known point of chromosomal integration into F
lac
, and the second used a series of transfer-deficient Hfr deletion strains to map a locus required in
cis
for chromosome transfer by an incoming F
lac
factor. Both techniques gave results consistent with a location for the origin of transfer between
traJ
and the φ
R
11
locus.
Mercury Resistance in a Plasmid-Bearing Strain ofEscherichia coli
Authors: Summers Anne O. , Silver Simon
Published: January 2020

A strain ofEscherichia colicarrying genes determining mercury resistance on a naturally occurring resistance transfer factor (RTF) converts 95% of 10−5mHg2+(chloride) to metallic mercury at a rate of 4 to 5 nmoles of Hg2+per min per 108cells. The metallic mercury is rapidly eliminated from the culture medium as mercury vapor. The volatilizing activity has a temperature dependence and heat sensitivity characteristic of enzymatic catalysis and is inducible by mercuric chloride. Ag+and Au3+are markedly inhibitory of mercury volatilization.
Regulation of the Tyrosine Biosynthetic Enzymes in
Salmonella typhimurium
: Analysis of the Involvement of Tyrosyl-Transfer Ribonucleic Acid and Tyrosyl-Transfer Ribonucleic Acid Synthetase
Authors: Heinonen J. , Artz S. W. , Zalkin H.
Published: January 2020

Mutants of
Salmonella typhimurium
were isolated that require tyrosine for growth because of an altered tyrosyl-transfer ribonucleic acid (tRNA) synthetase. Extracts of one strain (JK10) contain a labile enzyme with decreased ability to transfer tyrosine to tRNA
Tyr
and a higher
K
m
for tyrosine than the wild-type enzyme. Strain JK10 maintains repressed levels of the tyrosine biosynthetic enzymes when the growth rate is restricted due to limitation of charged tRNA
Tyr
. Several second-site revertants of strain JK10 exhibit temperature-sensitive growth due to partially repaired, heat-labile tyrosyl-tRNA synthetase. The tyrosine biosynthetic enzymes are not derepressed in thermosensitive strains grown at the restrictive temperature. A class of tyrosine regulatory mutants, designated
tyrR
, contains normal levels of tyrosyl-tRNA synthetase and tRNA
Tyr
. These results suggest that charging of tRNA
Tyr
is not necessary for repression. This conclusion is substantiated by the finding that 4-aminophenylalanine, a tyrosine analogue which causes repression of the tyrosine biosynthetic enzymes, is not attached to tRNA
Tyr
in vivo, nor does it inhibit the attachment reaction in vitro. A combined regulatory effect due to the simultaneous presence of
tyrS
and
tyrR
mutations in the same strain was detected. The possibility of direct participation of tyrosyl-tRNA synthetase in tyrosine regulation is discussed.
Anomalies in the Sedimentation of Deoxyribonucleic Acid from
Haemophilus influenzae
in Alkaline Sucrose Gradients
Authors: Kantor George J.
Published: January 2020

Difficulties were experienced in obtaining reproducible results for the sedimentation in alkaline sucrose gradients of
Haemophilus influenzae
deoxyribonucleic acid (DNA). The technique of McGrath and Williams of lysing whole cells on top of an alkaline sucrose gradient was employed. The addition of 0.2% sodium lauryl sulfate to the 0.2
n
NaOH lysing solution and reduction of the hemin concentration in the growth medium increased the reproducibility to 100% for log-phase cells handled in a manner mimicking the handling procedure used for irradiating cells with ultraviolet light. Distributions of DNA with number average molecular weights of 200 × 10
6
were routinely obtained by using these modifications.
“Periplasmic” Location of a β-Lactamase Specified Either by a Plasmid or a Chromosomal Gene in
Escherichia coli
Authors: Curtis N. A. C. , Richmond M. H. , Sykes R. B.
Published: January 2020

Type IIIa β-lactamase (TEM β-lactamase) was “periplasmic” in
Escherichia coli
K-12 regardless of whether its gene was chromosomal or carried on an R factor.
Plasmid-Associated Functions of a Stable F
lac
Authors: Macrina Francis L. , Balbinder Elias
Published: January 2020

Several functions associated with the stable plasmid, F
lac
S, have been examined. Our results indicate that the sex pili synthesized by
Escherichia coli
strains carrying F
lac
S are altered in some manner as evidenced by a very inefficient adsorption of male-specific phages. On the other hand, F
lac
S-mediated entry exclusion of related plasmids and plasmid incompatibility function(s) appear normal. The presence of covalently closed circular deoxyribonucleic acid in
E. coli
strains harboring F
lac
S indicates that it is an autonomously replicating plasmid. Based on β-galactosidase levels and the percentage of covalently closed circular deoxyribonucleic acid, it appears that the stability of the F
lac
S is not the result of multiple copies of this plasmid. F
lac
S appears larger than its precursor, F
ts114
lac
, in sedimentation through alkaline sucrose gradients.
Electron Microscopy of Some Special Cell Contacts in Yeasts
Authors: Rij N. J. W. Kreger-Van , Veenhuis M.
Published: January 2020

Anastomosis in
Endomycopsis javanensis
and some other filamentous yeasts was brought about by contact of a denticle from one cell with the wall of another cell, resulting in the disappearance of the outer layer and the thickening of the inner layer of the cell wall of the contacted cell. Another form of contact between cells was the penetration of one cell by a denticle on another cell which had grown out to a stalk; this occurred between cells of
E. javanensis
and between cells of this species and other yeast species.
Specialized Subregions of the Bifunctional
hisB
Gene of
Salmonella typhimurium
Authors: Houston L. L.
Published: January 2020

Forty-three
hisB
mutants of
Salmonella typhimurium
have been screened to determine the molecular size of the resulting histidinol phosphate phosphatase activity, one of the activities of a bifunctional enzyme produced by this gene which also controls imidazole glycerol phosphate dehydrase activity. Mutation in
hisB
can lead to the loss of both phosphatase and dehydrase activities, or only of dehydrase activity. Through the use of nonsense mutants lacking dehydrase activity, a distinct point of transition was detected near the middle of
hisB
at which a dramatic change occurs in the size of the phosphatase enzyme that is synthesized. A missense mutant with a lesion in this region has a high-molecular-weight enzyme which is eluted in the void volume of a Sephadex G-200 column. The enzyme from nonsense mutants near the transition point have molecular weights near 40,000. Even though the buffer conditions are designed to favor the stabilization of the high-molecular-weight form, some mutants have both high- and low-molecular-weight forms. The polypeptide chain specified by the operator proximal part of
hisB
is sufficient to allow the expression of phosphatase activity. The synthesis of substantially less than the complete product of
hisB
resulted in association into a form similar to the native enzyme which was found in the void volume of a Sephadex G-200 column.
Genetic Control of “Flor” Formation by
Saccharomyces
Authors: Maria J. Santa , Vidal D.
Published: January 2020

The results described indicate that in
Saccharomyces
sp. the formation of “flor” is under the control of a single Mendelian gene for which is proposed the symbol “Fl.”
Acyl Carrier Protein in Mycoplasmas
Authors: Rottem Shlomo , Muhsam-Peled Ofra , Razin Shmuel
Published: January 2020

Acyl carrier protein (ACP) activity was determined by the malonyl-coenzyme A–CO
2
exchange reaction. It was highest in
Acholeplasma laidlawii
, lower in
A. granularum
, and lowest in
A. axanthum
. The sterol-requiring
Mycoplasma
species examined showed little or negligible ACP activity.
A. laidlawii
was capable of utilizing pantetheine or coenzyme A but not β-alanine as precursor for ACP synthesis. Its ACP could thus be labeled by growing the organisms with radioactive coenzyme A. The ACP of
A. laidlawii
appears to be a soluble cytoplasmic protein, which could be purified about 40-fold by treatment of the cytoplasmic fluid with streptomycin sulfate and chromatography of the supernatant fluid on a Biogel P-10 column. Its molecular weight, determined by polyacrylamide gel electrophoresis, is low (about 10,900) resembling that of
Escherichia coli
, but it is much more sensitive to heat.
Isolation and Characterization of Acid Phosphatase Mutants in
Saccharomyces cerevisiae
Authors: Toh-e Akio , Ueda Yoshinami , Kakimoto Sei-Ichiro , Oshima Yasuji
Published: January 2020

Saccharomyces cerevisiae
strain H-42 seems to have two kinds of acid phosphatase: one which is constitutive and one which is repressible by inorganic phosphate. The constitutive enzyme was significantly unstable to heat inactivation, and its
K
m
of 9.1 × 10
−4
m
for
p
-nitrophenylphosphate was higher than that of the repressible enzyme (2.4 × 10
−4
m
). The constitutive and the repressible acid phosphatases are specified by the
phoC
gene and by the
phoB
,
phoD
, or
phoE
gene, respectively. Results of tetrad analysis suggested that the
phoC
and
phoE
genes are linked to the
lys2
locus on chromosome II. Since both repressible acid and alkaline phosphatases were affected simultaneously in the
phoR, phoD
, and
phoS
mutants, it was concluded that these enzymes were under the same regulatory mechanism or that they shared a common polypeptide. The
phoR
mutant produced acid phosphatase constitutively, and the
phoR
mutant allele was recessive to its wild-type counterpart. The
phoS
mutant showed a phenotype similar to that of a mutant defective in one of the
phoB, phoD
, or
phoE
genes. However, the results of genetic analysis of the
phoS
mutant clearly indicated that the
phoS
gene is not a structural gene for either of the repressible acid and alkaline phosphatases, but is a kind of regulatory gene. According to the proposed model, the
phoS
gene controls the expression of the
phoR
gene, and inorganic phosphate would act primarily as an inducer for the formation of the
phoR
product which represses phosphatase synthesis.
Role of Adenosine 3′,5′-Cyclic Monophosphate and Its Specific Binding Protein in the Regulation of
d
-Serine Deaminase Synthesis
Authors: McFall Elizabeth
Published: January 2020

Adenosine 3′,5′-cyclic monophosphate (cyAMP) and the cyAMP-binding protein are necessary for efficient induction of
d
-serine deaminase (Dsdase) synthesis in
dsdC
+
dsdO
+
and
dsdC dsdO
+
strains of
Escherichia coli
K-12, and for constitutive synthesis in
dsdC dsdO
+
strains. Neither is required in
dsdO
strains, confirming previous indications that in
dsdO
mutants Dsdase synthesis is not subject to catabolite repression control. Since efficient Dsdase synthesis in
dsdC
+
and
dsdC
strains that are
dsdO
+
requires the cyAMP-binding protein, which acts at the level of transcription in other systems, it is concluded that catabolite repression acts at the level of transcription of the Dsdase structural gene. Since catabolite repression is reversed by the inducer,
d
-serine in
dsdC dsdO
+
strains, it is concluded that induction also acts at the level of transcription in this system. The
dsdC
strains were found to be much more sensitive to induction by
d
-serine than are
dsdC
+
strains under conditions of catabolite repression, whether the repression was caused by glucose or by loss of ability to form cyAMP or cyAMP-binding protein. This suggests that a
d
-serine-
dsdC
complex may be able to replace partially the cyAMP:cyAMP-binding protein action in initiation of Dsdase messenger ribonucleic acid synthesis—a positive control effect.
Isolation and Partial Characterization of Temperature-Sensitive Mutants in Ten Loci That Affect Cell Membrane Synthesis in
Escherichia coli
: Isolation and Genetic Sorting
Authors: Godson G. Nigel
Published: January 2020

Four hundred temperature-sensitive (ts) mutants were isolated by the
3
H-glycerol-3-phosphate membrane suicide procedure of Cronan, Ray, and Vagelos and were sorted into 13 groups by the rapid mapping procedures of Low. Recombination and complementation studies on representative members of each group suggested that the ts mutations of all 13 groups are present in genetically different complementation groups. Biochemical studies suggested that 10 of these ts mutations affected cell membrane synthesis. In this paper, the genetic data are presented in detail so that the limits of the Low rapid mapping procedures can be assessed, and in an accompanying paper the partial biochemical characterization of the ts mutations is described.
Effect of Phosphate Limitation on the Morphology and Wall Composition of
Bacillus licheniformis
and Its Phosphoglucomutase-Deficient Mutants
Authors: Forsberg C. W. , Wyrick P. B. , Ward J. B. , Rogers H. J.
Published: January 2020

Two very poorly lytic mutants of
Bacillus licheniformis
6346 that had no teichuronic acid or glucose in their walls were phosphoglucomutase deficient. The walls of the mutants were less autolytic, and the lesion in the phosphoglucomutase gene and the formation of lytic amidase seemed to be interrelated. When phosphoglucomutase was regained or the effects of the deficiency were circumvented by the presence of galactose in the medium, the lytic enzyme was partially regained. When subjected to growth limitation by the supply of inorganic phosphate, the mutants ceased to make teichoic acid, and their walls contained a greatly increased proportion of mucopeptide. Under these conditions they formed irregular spheres which changed back to rods when inorganic phosphate was supplied. Both wall and protein synthesis were necessary for the changes in morphology. An intermediate crescent-shaped cell was formed in the change from sphere to a rod. The possible relationship of this morphological change to the distribution of biosynthetic sites is discussed.
Taxonomy of Marine Bacteria:
Beneckea parahaemolytica
and
Beneckea alginolytica
Authors: Baumann Paul , Baumann Linda , Reichelt John L.
Published: January 2020

A collection of 169 strains, including 91 obtained from cases of gastroenteritis and 41 from localized tissue infections and infections of the eye and ear, was submitted to an extensive nutritional, physiological, and morphological characterization. The nutritional and physiological data obtained from these strains, as well as data for strains of other species of the genus
Beneckea
, were submitted to a numerical analysis which grouped the strains into clusters on the basis of phenotypic similarity. Strains from cases of gastroenteritis formed a group of three clusters which linked at a similarity value of 68%. These three clusters could not, however, be separated from each other by universally positive or negative traits, and on the basis of their overall phenotypic similarity were assigned to a single species,
B. parahaemolytica
. The majority of the strains from human, nonenteric sources segregated into two distinct clusters, one designated
B. alginolytica
and the other unassigned with respect to species (group C-2).
B. parahaemolytica, B. alginolytica
, and group C-2 could be readily distinguished from one another as well as from the remaining species of the genus
Beneckea
by multiple, unrelated, phenotypic traits. Activities of selected enzymes of glucose and gluconate catabolism in cell-free extracts of
B. parahaemolytica, B. alginolytica
, and group C-2 suggested that these organisms utilized glucose primarily via the Embden-Meyerhof pathway and gluconate primarily via the Entner-Doudoroff pathway. Similar results were observed in the other members of the genus
Beneckea
.
Catalytic Studies on Tryptophanase fromBacillus alvei
Authors: Hoch Sallie O'Neil , DeMoss R. D.
Published: January 2020

Tryptophanase fromBacillus alveiexhibited the expected spectrum of pyridoxal-5′-phosphate-dependent reactions. It exhibitedl-serine dehydratase,S-alkyl-cysteine lyase, and cysteine desulfhydrase activities, as well as the classic tryptophanase reactions (all beta elimination reactions). It also acted as a tryptophan synthetase (beta replacement reactions) using indole plusl-serine orl-cysteine orS-methyl-cysteine as substrates. The beta elimination reactions are simple competitors of the replacement reactions for the same amino acid substrates. The kinetics of the reactions were examined in detail using a coupled continuous spectrophotometric assay. A product (indole) inhibition study of the beta elimination reaction with tryptophan showed simple, noncompetitive inhibition; the same study with allosubstrates showed noncompetitive inhibition by indole. These product studies provided data on the beta replacement reactions as well. The results are discussed in terms of a mechanism for theB. alveitryptophanase.
Proteins Released from Cell Envelopes of
Pseudomonas aeruginosa
on Exposure to Ethylenediaminetetraacetate: Comparison with Dimethylformamide-Extractable Proteins
Authors: Stinnett J. D. , Gilleland H. E. , Eagon R. G.
Published: January 2020

Isolated cell envelopes of
Pseudomonas aeruginosa
were treated with
N,N
′-dimethylformamide (DMF) or with ethylenediaminetetraacetate (EDTA). DMF solubilized 73% of the dry weight of the cell envelope, 76% of the protein, 78% of the carbohydrate, and 76% of the phosphorus. Electron microscopy showed that DMF caused extensive alterations in the appearance of the cell envelope with blebs and bleblike vesicles predominating. After incubation with EDTA, the cell envelopes appeared to have lost material, but still retained the cell-like morphology. Analysis of DMF-solubilized proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed 16 protein bands. There were three major proteins that predominated, however, with molecular masses of 43,000 (protein A), 16,500 (protein B), and 72,000 daltons (protein C). Evidence is presented that protein A and protein B are glycoproteins. Gel electrophoresis of EDTA-solubilized material revealed that a number of proteins were released from the cell envelope. However, electrophoresis of an isolated protein-lipopolysaccharide complex released by EDTA showed that protein A and protein B were the major protein components of this complex. These data suggest that protein A and protein B are components of the outer cell wall membrane of
P. aeruginosa
. There is suggestive evidence that these proteins may play a role in maintaining the structural integrity of the cell envelope. Whether these proteins also have enzymatic activity could not be discerned from the present study, although it is possible that they may be associated with the terminal stages of lipopolysaccharide synthesis.
Study of Phenoloxidase Activity During the Reproductive Cycle in
Schizophyllum commune
Authors: Leonard Thomas J. , Phillips Lou Ellen
Published: January 2020

A study of the temporal relationship between the appearance of phenoloxidase activity and the formation of fruiting bodies in
Schizophyllum commune
was undertaken. The results indicate that phenoloxidase activity increases in colonies subsequent to the formation of aggregate masses of hyphae, continues to increase until mature, sporulating fruiting structures are produced, and then declines significantly.
Escherichia coliMutants Permissive for T4 Bacteriophage with Deletion ineGene (Phage Lysozyme)
Authors: Raj C. V. Sundar , Wu H. C.
Published: January 2020

Escherichia colimutants have been isolated that are permissive for the infection by T4 phage with deletion in the cistron for the phage lysozyme, theegene. Some, but not all, of these mutants are simultaneously permissive for the infection by T4 phage defective in thetgene, the product of which has also been implicated in the release of progeny phages. Most of these mutants shared the following properties: temperature sensitivity in growth and cell division, increased sensitivity towards a number of unrelated antibiotics and colicins, and increased sensitivity towards anionic detergents (sodium dodecyl sulfate and sodium deoxycholate). The possible biochemical basis for these phenotypes is discussed.
Kinetic Studies on the Interaction of Bacteriophage Type 71 Staphylococcal Bacteriocin with Susceptible Bacteria
Authors: Dajani Adnan S. , Wannamaker Lewis W.
Published: January 2020

Kinetic studies on the interaction of the bacteriocin produced by phage type 71
Staphylococcus aureus
with susceptible bacterial cells were undertaken. Survivors among susceptible bacteria to which the bacteriocin has been added can be rescued after trypsin treatment. The bacteriocin adsorbs very rapidly to susceptible streptococcal cells at a time when killing of the cells is only minimal. Heat-killed or mechanically disrupted cells are also effective in adsorbing the bacteriocin. Adsorption is comparable at 37 C and 25 C, but is less pronounced at 4 C. Elution of adsorbed bacteriocin could not be achieved by heating, by varying pH, or by using different concentrations of sodium chloride solutions. Surface M protein of streptococcal cells plays no role in the adsorptive process. Adsorption is specific in that only susceptible bacteria, but not resistant ones, are capable of adsorbing the bacteriocin.
Enzyme Complex Which Couples Glycerol-3-Phosphate Dehydrogenation to Fumarate Reduction in
Escherichia coli
Authors: Miki K. , Lin E. C. C.
Published: January 2020

Anaerobic growth of
Escherichia coli
on glycerol as carbon source and fumarate as hydrogen acceptor results in the induction of both anaerobic
sn
-glycerol-3-phosphate (G3P) dehydrogenase and fumarate reductase. In previous studies, the G3P dehydrogenase was measured by the G3P-dependent reduction of a tetrazolium dye mediated by phenazine methosulfate in the presence of flavine mononucleotide and flavine adenine dinucleotide, and fumarate reductase was measured by the fumarate-dependent oxidation of reduced flavine mononucleotide. Results from the present study indicate that these two enzymes actually constitute a functional complex which is sedimentable at 200,000 ×
g
in 2 h and which can catalyze the dehydrogenation of G3P at the expense of fumarate without any added cofactor. This coupling activity is not constituted by simply mixing an extract containing anaerobic G3P dehydrogenase with another extract containing fumarate reductase. Additional evidence for an organized complex is provided by the high degree of sensitivity of the coupled reaction to low concentrations of the detergents Triton X-100 and Emasol 1130 in comparison with the individual activities of the two component enzymes measured with the aid of artificial cofactors.
Role of Cyclic Adenosine 3′,5′-Monophosphate in the In Vivo Expression of the Galactose Operon of
Escherichia coli
Authors: Rothman-Denes Lucia B. , Hesse Joanne E. , Epstein Wolfgang
Published: January 2020

Studies of levels of galactokinase in
Escherichia coli
with mutations affecting synthesis of, or response to, cyclic adenosine 3′,5′-monophosphate show that this nucleotide does not play a major role in expression of the galactose operon, causing at most a twofold stimulation. The discrepancy between our in vivo results and the marked stimulation by cyclic adenosine 3′,5′-monophosphate in in vitro systems indicates that current cell-free systems lack a factor which allows efficient expression of the galactose operon even in the absence of cyclic adenosine 3′,5′-monophosphate or of the binding protein for this nucleotide.
Model for the Structure of the Shape-Maintaining Layer of the
Escherichia coli
Cell Envelope
Authors: Braun Volkmar , Gnirke Helga , Henning Ulf , Rehn Kurt
Published: January 2020

The surface area per repeating murein unit (i.e. per molecule of diaminopimelate) has been determined for the cell envelopes of the
Escherichia coli
strains K-12 and W. This area was constantly found to be 1.3 nm
2
. Using this value and other previously determined properties of
E. coli
murein, a three-dimensional model of murein is proposed. The model specifies a monomolecular layer in which disaccharide units are each 1.03 nm long, and the polysaccharide chains, all parallel, are 1.25 nm apart. The cross-linking peptide side-chains have the same atomic coordinates and are arranged above or below the polysaccharide chains.
Extractable Lipids of Gram-Negative Marine Bacteria: Phospholipid Composition
Authors: Oliver James D. , Colwell Rita R.
Published: January 2020

Phospholipid compositions of 20 strains of marine and estuarine bacteria were determined. Results showed that phospholipids of marine bacteria differed very little from those of nonmarine organisms with phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol being the predominant phospholipids in all strains examined. Lyso-phosphatidylethanolamine occurred in significant quantities among a number of the marine bacteria, and two of the isolates contained significant quantities of poly-β-hydroxybutyrate. Effects of age and growth temperature on the phospholipid composition were also investigated. It is suggested that phylogenetic relationships among bacteria may be correlated with phospholipid composition.
Plasmid-Specific Transformation in
Staphylococcus aureus
Authors: Lindberg Martin , Novick Richard P.
Published: January 2020

Transformation of
Staphylococcus aureus
cells with circular duplex deoxyribonucleic acid prepared from plasmid-carrying strains by alkali denaturation and selective renaturation or by dye-buoyant density centrifugation is reported. In all of the transformants tested, the transformed markers became established as autonomous plasmids that were biologically and physically indistinguishable from those carried by the donor strains. Transformation with bulk deoxyribonucleic acid from a strain carrying the penicillinase plasmid, PI
258
, gave rise to transformants in which the erythromycin locus, the only plasmid marker transformed, was shown to be integrated into the host chromosome.
Common Enzymes of Branched-Chain Amino Acid Catabolism in
Pseudomonas putida
Authors: Martin Ronald R. , Marshall Vincent D. , Sokatch John R. , Unger Leon
Published: January 2020

Two types of
Pseudomonas putida
PpG2 mutants which were unable to degrade branched-chain amino acids were isolated after mutagenesis and selection for ability to grow on succinate, but not valine, as a sole source of carbon. These isolates were characterized by growth on the three branched-chain amino acids (valine, isoleucine, and leucine), on the corresponding branched-chain keto acids (2-ketoisovalerate, 2-keto-3-methylvalerate, and 2-ketoisocaproate), and on other selected intermediates as carbon sources, and by their enzymatic composition. One group of mutants lost 2-ketoisovalerate-inducible branched-chain keto acid dehydrogenase that was active on all three keto acids. There was also a concomitant loss of ability to grow on all three branched-chain amino acids as well as on all three corresponding keto acids, but there was retention of ability to use subsequent intermediates in the catabolism of branched-chain amino acids. Another type of mutant showed a marked reduction in branched-chain amino acid transaminase activity and grew poorly at the expense of all three amino acids, but it utilized subsequent intermediates as carbon sources. Both the transaminase and branched-chain keto acid dehydrogenase mutants retained the ability to degrade camphor. These findings are consistent with the view that branched-chain amino acid transaminase and branched-chain keto acid dehydrogenase are common enzymes in the catabolism of valine, isoleucine, and leucine.
Phenotypic Suppression of a Fructose-1, 6-Diphosphate Aldolase Mutation in
Escherichia coli
Authors: Schreyer Renate , Böck August
Published: January 2020

Strain NP 315 of
Escherichia coli
possesses a thermolabile fructose-1, 6-diphosphate (FDP) aldolase; its growth on carbohydrate substrates is inhibited probably as a consequence of the accumulation of high intracellular levels of FDP. Studies of one class of phenotypic revertants of strain NP 315 which have regained their ability to grow on C
6
substrates at 40 C showed that in these strains the buildup of the inhibitory FDP pool is prevented by additional mutations in enzymes catalyzing the conversion of the substrate offered in the medium to FDP. For example, mutations affecting 6-phosphogluconate dehydrogenase activity (
gnd
−
) may be selected in great number without any mutagenesis and enrichment simply by isolating revertants of strain NP 315 able to grow on gluconate at 40 C. Similarly, an additional mutation in phosphoglucose isomerase (
pgi
−
) restores the ability of these
fda
−
gnd
−
strains to grow on glucose at 40 C. Glucose metabolism of these
fda
−
gnd
−
pgi
−
strains was investigated. The enzymes of the Entner-Doudoroff pathway are induced to an appreciable extent upon growth of these mutants on glucose medium; further evidence for glucose degradation via this route (which normally is induced only in the presence of gluconate) was provided by following the fate of the C1 label of radioactive glucose in
l
-alanine. Predominant labeling of the carboxyl-carbon of
l
-alanine was observed, inciating a major contribution of the Entner-Doudoroff path to pyruvate formation from glucose. Chromatographic analysis of the intermediates of glucose metabolism showed further that glucose apparently is at least partly metabolized via a bypass consisting of the accumulation of extracellular gluconic acid which arises by dephosphorylation of 6-phosphogluconolactone and possibly of 6-phosphogluconate. This extracellular gluconate is then taken up and metabolized in the normal manner via the Entner-Doudoroff enzymes.
Suppression of Photoreactivating Enzyme Production in
Escherichia coli
Grown Under Anaerobic Conditions
Authors: Tyrrell Rex M.
Published: January 2020

Studies with two K-12 mutants of
Escherichia coli
have indicated that the production of photoreactivating enzyme is suppressed under anaerobic growth conditions. Under no condition tested could the estimated number of photoreactivating enzyme molecules per cell be reduced below an average of one.
Deoxyribonucleic Acid Breaks in Heated
Salmonella typhimurium
LT-2 After Exposure to Nutritionally Complex Media
Authors: Gomez Reinaldo F. , Sinskey Anthony J.
Published: January 2020

Minimal medium recovery of heat-treated
Salmonella typhimurium
LT-2 has been expressed as the reduced viability on trypticase soy agar supplemented with 0.5% yeast extract (TSY) relative to a glucose-salts (M-9) agar. Incubation of
S. typhimurium
LT-2 in water at 50 C for 15 min did not change the sedimentation patterns of deoxyribonucleic acid (DNA) in alkaline sucrose gradients. The same pattern was obtained if the heated cells were further incubated for 15 min at 37 C in M-9 broth. However, a marked increase in DNA single-strand breakage accompanied by a loss of viability was observed after a similar incubation of heated bacteria in TSY broth. If heated bacteria were incubated in M-9 broth before TSY broth, there was a decrease in the single-strand breakage occurring in the TSY broth. This decrease is believed to be the result of repair of heat-induced damage. We conclude that minimal medium recovery after heat treatment is due to DNA damage caused by sequential exposure to heat and TSY medium, such damage not occurring after sequential exposure to heat and M-9 medium.
d
-Alanine Oxidase from
Escherichia coli
: Localization and Induction by
l
-Alanine
Authors: Raunio R. P. , Jenkins W. T.
Published: January 2020

Dialyzed membranes of
Escherichia coli
prepared by an ethylenediaminetetraacetic acid-lysozyme method catalyze the oxidation of both
l
-alanine and
d
-alanine. The specific activities for the oxidations of both
d
-alanine and
l
-alanine are increased fivefold when the cells are grown in the presence of either
l
-alanine or
dl
-alanine, but are increased only slightly when grown in the presence of
d
-alanine. In the
dl
-alanine-induced system, the specific activities for the oxidations of some other
d
-amino acids are also raised.
dl
-alanine also induces two other alanine catabolizing enzymes, alanine dehydrogenase and alanine-glutamate aminotransferase which are found in the “soluble” fraction of lysozyme-treated cells. The oxidations of both
l
-alanine and
d
-alanine were associated with the membranes of induced cells. After the membranes were disintegrated by sonic treatment, both
l
-alanine and
d
-alanine oxidation catalysts sedimented in a sucrose density gradient together with
d
-lactate and
l
-lactate dehydrogenases, apparently as a single multienzyme complex.
Novel Mutation to Dominant Fucose Resistance in the
l
-Arabinose Operon of
Escherichia coli
Authors: Nathanson Neil M. , Schleif Robert
Published: January 2020

We isolated an unusual mutant in which the arabinose operon carried an
araC
lesion that led to a dominant fucose resistance while retaining recessive constitutivity. All previously characterized C
c
mutations have been recessive for both fucose resistance and constitutivity.
Characterization of Invertase Activity from Cariogenic
Streptococcus mutans
Authors: Kuramitsu Howard K.
Published: January 2020

Invertase activity from
Streptococcus mutans
GS-5 has been partially purified and shown to possess β-fructofuranosidase specificity. The enzyme has a broad pH optimum between pH 5.5 and 7.5 and exhibits maximal activity at 37 C. Fructose, but not the glucose analogue α-methyl-
d
-glucoside, acts as a competitive inhibitor of the enzyme. None of the common glycolytic intermediates or adenine nucleotides had any significant effect on enzyme activity. A molecular weight of approximately 47,000 was estimated for the enzyme. The enzyme does not appear to be catabolically repressed by glucose nor inducible by sucrose. Higher specific activities of the enzyme are observed in fructose or glucose-grown cells compared to sucrose-grown cells. These results are discussed in terms of the regulation of invertase activity in vivo.
Nucleoid Condensation and Cell Division in
Escherichia coli
MX74T2
ts52
After Inhibition of Protein Synthesis
Authors: Zusman David R. , Carbonell Augustina , Haga Juli Y.
Published: January 2020

The reorganization of the bacterial nucleoid of an
Escherichia coli
mutant, MX74T2
ts52
, was studied by electron microscopy after protein synthesis inhibition by using whole mounts of cell ghosts, ultrathin-sectioning, and freeze-etching. The bacterial nucleoid showed two morphological changes after chloramphenicol addition: deoxyribonucleic acid (DNA) localization and DNA condensation. DNA localization was observed 10 min after chloramphenicol addition; the DNA appeared as a compact, solid mass. DNA condensation was observed at 25 min; the nucleoid appeared as a cytoplasm-filled sphere, often opened at one end. Ribosomes were observed in the center. Giant nucleoids present in some mutant filaments showed fused, spherical nucleoids arranged linearly, suggesting that the tertiary structure of the nucleoid reflects the number of replicated genomes. Inhibitors which directly or indirectly blocked protein synthesis and caused DNA condensation were chloramphenicol, puromycin, amino acid starvation, rifampicin, or carbonyl cyanide
m
-chlorophenyl hydrazone. All inhibitors that caused cell division in the mutant also caused condensation, although some inhibitors caused condensation without cell division. Nucleoid condensation appears to be related to chromosome structure rather than to DNA segregation upon cell division.
Effects of Ethylenediaminetetraacetate and Chloramphenicol on Mitochondrial Activity and Morphogenesis inMucor rouxii
Authors: Zorzopulos Jorge , Jobbagy Andres J. , Terenzi Hector F.
Published: January 2020

The present study demonstrates the importance of mitochondrial activities in controllingMucor rouxiimorphogenesis. The respiratory capacity of the spores of this facultatively anaerobic, dimorphic fungus becomes repressed if germination and growth take place in the absence of oxygen. The level of activity of mitochondrial enzymes such as cytochrome oxidase and malate dehydrogenase is lower in the anaerobic yeastlike cells than it is in ungerminated spores and in aerobic hyphae, but the reverse is true for glycolytic enzymes such as pyruvate kinase and alcohol dehydrogenase. Following exposure to air, yeastlike cells convert into hyphae after a lag period corresponding to aerobic adaptation. Anaerobic cultures grown in the presence of ethylenediaminetetraacetate (EDTA) at a concentration of 10−4M exhibit hyphal morphology. These cells, which are fully adapted to anaerobic fermentation, nevertheless have potentially active mitochondria with the same levels of respiratory enzymes as ungerminated spores. These cells are able to grow immediately after aeration, without an adaptation lag. Evidence is presented which indicates that the morphogenetic effect of EDTA is not the result of elimination of free metals. Additional evidence proving mitochondrial control of morphogenesis inM. rouxiiis that chloramphenicol (4 mg/ml) induced the formation of respiratory-deficient, yeastlike cells in aerobic cultures.
Coupling Between Chromosome Completion and Cell Division in
Escherichia coli
Authors: Dix Douglas E. , Helmstetter Charles E.
Published: January 2020

The relationship between termination of chromosome replication and cell division was investigated in
Escherichia coli
B/r. Synchronous cultures of
E. coli
B/r growing in glucose minimal medium or subjected to a nutritional shift-up were exposed to chloramphenicol, rifampin, mitomycin C, or nalidixic acid, and the ability of cells to divide in the presence of the inhibitors was measured. It was found that cell division became resistant to inhibitors of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) synthesis at approximately the same stage in the division cycle in all situations investigated. When the synchronous glucose-grown cultures were temporarily exposed to chloramphenicol early in the division cycle and then exposed to mitomycin C or nalidixic acid immediately after removal of chloramphenicol, the cells did not divide. In contrast, when DNA synthesis was inhibited by thymine starvation immediately after temporary exposure to chloramphenicol, cells divided. The results suggest that DNA chain elongation is completed in some cells in the absence of protein synthesis, but that additional steps involving specific RNA or protein synthesis, or both, may be required for processing the chromosomal structures to the form which is necessary for division. This processing, which normally occurs concurrent with DNA synthesis and is prevented by inhibitors of DNA synthesis, may trigger division. Alternatively, in the absence of protein synthesis, all aspects of chromosome formation may be completed, but final transcriptional events which are essential for division cannot take place until the complete synthesis of a critical amount of specific proteins.
Transduction of Lactose Metabolism in
Streptococcus lactis
C2
Authors: McKay L. L. , Cords B. R. , Baldwin K. A.
Published: January 2020

Ultraviolet (UV)-induced phage lysates, from lactose-positive (
lac
+
)
Streptococcus lactis
C2, transduced lactose fermenting ability to
lac
−
recipient cells of this organism. Although the phage titer could not be determined due to the absence of an appropriate indicator strain, the number of transductants was proportional to the amount of phage lysate added. Treatment of the lysate with deoxyribonuclease had no effect on this conversion, indicating the observed genetic change was not mediated by free deoxyribonucleic acid. When the
lac
+
transductants were isolated and exposed to UV irradiation, lysates with higher transducing ability were obtained. The transducing ability of this lysate was about 100-fold higher than that observed in the original lysates. The
lac
+
transductants were unstable since
lac
−
segregants occurred at high frequency. The phage lysate from
S. lactis
C2 also transduced maltose and mannose metabolism to the respective negative recipient cells. The results demonstrate the transduction of carbohydrate markers by a streptococcal phage and establish a genetic transfer system in group N streptococci.
The
hisP
Protein, a Known Histidine Transport Component in
Salmonella typhimurium
, Is Also an Arginine Transport Component
Authors: Kustu Sydney Govons , Ames Giovanna Ferro-Luzzi
Published: January 2020

The
hisP
protein is an essential component of the high-affinity histidine transport system in
Salmonella typhimurium
. Our present studies demonstrate that this protein is also an essential component of an arginine transport system. Strains with a mutation in the
hisP
gene are unable to transport arginine for use as a sole nitrogen source. However, such strains have normal high-affinity transport of arginine, indicating that the
hisP
protein is not required for all arginine transport systems. Histidine does not appear to compete with arginine for transport through the
hisP
system, suggesting that the
hisP
protein may not be a “carrier” for these amino acids. The
hisJ
protein, a periplasmic histidine-binding protein, is known to function in conjunction with the
hisP
protein in the transport of histidine. The
hisJ
protein does not function with the
hisP
protein in arginine transport.
NH2-Terminal Amino Acid Distribution and Amino Acid Composition ofStreptococcus faecalisR Soluble and Ribosomal Proteins
Authors: Samuel Charles E. , Murray Cheryl L. , Rabinowitz Jesse C.
Published: January 2020

The NH2-terminal amino acid distribution ofStreptococcus faecalisR soluble and ribosomal proteins isolated from cells at different stages of growth on either folate-sufficient or folate-deficient medium was determined by the dinitrophenyl method. The NH2-terminal residues do not follow the random distribution observed for the total amino acid composition ofS. faecalissoluble and ribosomal proteins. Methionine and alanine occur most frequently; serine, threonine, aspartic and glutamic acids, and glycine are also present at the NH2-terminal position ofS. faecalisR proteins. The absence of folic acid yields cells that are incapable of formylating methionyl-transfer ribonucelic acid tRNAfMet, but does not affect either the qualitative or quantitative NH2-terminal distribution of total soluble or total ribosomal proteins compared to cells grown with folate. A small quantitative difference was observed in the frequency of distribution of certain amino acids at the NH2-termini between log and stationary phase soluble proteins. The amino acid residues found at the NH2-terminal position ofS. faecalisproteins are qualitatively similar to those reported for several other organisms.
Localization of Alkaline Phosphatase in Three Gram-Negative Rumen Bacteria
Authors: Cheng K.-J. , Costerton J. W.
Published: January 2020

Of the three species (
Bacteroides ruminicola, B. succinogenes
, and
Megasphaera elsdenii
) of anaerobic gram-negative rumen bacteria studied, only
B. ruminicola
produced significant amounts of alkaline phosphatase. This enzyme, which is constitutive, showed a greater affinity for
p
-nitrophenylphosphate than for sodium-β-glycerophosphate and was shown to be located exclusively in the periplasmic space of log-phase cells. Small amounts of this enzyme were released from these cells in stationary-phase cultures, but washing in 0.01 M MgCl
2
and the production of spheroplasts by using lysozyme in 0.01 M MgCl
2
did not release significant amounts of the enzyme. Exposure to 0.2 M MgCl
2
did not release significant amounts of the periplasmic alkaline phosphatase of the cell, and when these cells were spheroplasted with lysozyme in 0.2 M MgCl
2
only 25% of the enzyme was released. Spheroplasts were formed spontaneously in aging cultures of
B. ruminicola
, but even these cells retained most of their periplasmic alkaline phosphatase. It was concluded that the alkaline phosphatase of
B. ruminicola
is firmly bound to a structural component within the periplasmic area of the cell wall and that the enzyme is released in large amounts only when the cells break down. The behavior of alkaline phosphatase in this bacterium contrasts with that of conventional periplasmic enzymes of aerobic bacteria, which are released upon conversion into spheroplasts by lysozyme and ethylenediaminetetraacetic acid and by other types of cell wall damage. All three species of bacteria studied here, as well as bacteria found in mixed populations in the rumen, have thick, complex layers external to the double-track layer of their cell walls. In addition,
B. ruminicola
produces a loose extracellular material.
Sensitization by Ethylenediaminetetraacetate of
Clostridium perfringens
Type A Spores to Germination by Lysozyme
Authors: Adams D. M.
Published: January 2020

Clostridium perfringens
spores (three strains) were normally resistant to germination by lysozyme. In the absence of disulfide bond-breaking reagents, tetrasodium ethylenediaminetetraacetate rapidly sensitized the spores to lysozyme.
Production of Bacteriophage by Temperature-Sensitive Sporulation Mutants of
Bacillus cereus
T
Authors: Stelma G. N. , Sadoff H. L.
Published: January 2020

Five temperature-sensitive sporulation mutants of
Bacillus cereus
T have been isolated. These mutants are blocked at stage 0 of sporulation at the restrictive temperature (37 C) but are able to sporulate at nearly normal frequencies at the permissive temperature (26 C). A bacteriophage that forms a stable lysogen in the parent strain is induced at increased frequencies in the mutants. This induction is accompanied, in some of the mutants, by a reduction in immunity to the phage. Revertants, selected for their ability to sporulate normally at both temperatures, lose their ability to produce high titers of the phage. In addition to this lytic phage, an apparently defective phage has been found in lysates of the mutants. Strains cured of the plaque-forming phage still carry the defective phage. Comparisons of physical and biological properties of the plaque-forming phage with those of the two
Bacillus cereus
phages most similar to it have shown that this phage is not identical to either of them. The maximal titer of phage produced in cultures of the parent strain is about 10
3
plaque-forming units (PFU) per ml at both temperatures. The maximal titers of phage produced by the mutant are 4 × 10
9
PFU/ml at 37 C and 7 × 10
8
PFU/ml at 26 C. Both mutant and parent strains release over 90% of the phage they produce after the onset of stationary phase.