bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Basis for the Transformation Defects in Mutants of
Haemophilus influenzae
Authors: Notani N. K. , Setlow Jane K. , Joshi Vijaya R. , Allison D. P.
Published: January 2020

To determine the molecular basis of transformation defects in
Haemophilus influenzae
, the fate of genetically marked,
32
P-labeled, heavy deoxyribonucleic acid (DNA) was examined in three mutant strains (
rec
1
−
,
rec
2
−
, and KB6) and in wild type having
3
H-labeled DNA and a second genetic marker. Transforming cells upon lysis with digitonin followed by low-speed centrifugation are separable into the supernatant fraction, containing mainly the unintegrated donor DNA, and the pellet, containing most of the resident DNA along with integrated donor DNA. Electron micrographs of digitonin-treated cells also indicate that the resident DNA is trapped inside a cellular structure but that cytoplasmic elements such as ribosomes are extensively released. DNA synthesis in digitonin-treated cells is immediately blocked, as is any further integration of donor DNA into the resident genome. Isopycnic and sedimentation analysis of supernatant fluids and pellets revealed that in strains
rec
2
−
and KB6 there is little or no association between donor and resident DNA, and thus there is negligible transfer of donor DNA genetic information. In these strains, the donor DNA is not broken into pieces of lower molecular weight as it is in strain
rec
1
−
and in the wild type, both of which show association between donor and recipient DNA. In strain
rec
1
−
, although some donor DNA atoms become covalently linked to resident DNA, the incorporated material does not have the donor DNA transforming activity.
Deletion Map of the
Escherichia coli
K-12 Sex Factor F: the Order of Eleven Transfer Cistrons
Authors: Ippen-Ihler K. , Achtman M. , Willetts N.
Published: January 2020

A series of Hfr deletion mutants was isolated. These mutants contain deletions which extend from a λ prophage into an F
lac
which is integrated into the
gal
operon. Transfer-deficient deletion mutants were found to fall into four different phenotypic groups when tested for male- and female-specific phage resistance. Conjugational and transductional complementation tests with F
lac
point mutants deficient in transfer (
tra
−
) were performed, and the order of 11
tra
cistrons was determined. The
tra
genes are all located between an F gene for the inhibition of female-specific phages and the transposed
lac
operon originally carried by the F
lac
. The order of genes in the Hfr studied was established to be:
pro
C... φ
II

R

...
traJ traA traE traK traB traC traF traH traG traD traI...lac...attλ...bio
.
Correlation Between Hydrolysis of the β-Lactam Bond of the Cephalosporin Nucleus and Expulsion of the 3-Substituent
Authors: O'Callaghan Cynthia H. , Kirby Susan M. , Morris A. , Waller R. E. , Duncombe R. E.
Published: January 2020

The hydrolysis of two cephalosporins by three different β-lactamases has been studied. Each enzyme caused a decrease in ultraviolet absorption, a loss of biological activity, and the release of the leaving group from the 3-position. The changes occurred at the same rate and to the same extent with each enzyme, and it is inferred that the loss of the leaving group is a consequence of, and not a prerequisite for, hydrolysis of the β-lactam ring.
Documentation of Auxotrophic Mutation in Blue-Green Bacteria: Characterization of a Tryptophan Auxotroph in
Agmenellum quadruplicatum
Authors: Ingram Lonnie O. , Pierson Duane , Kane James F. , Van Baalen C. , Jensen Roy A.
Published: January 2020

A tryptophan-requiring auxotroph of
Agmenellum quadruplicatum
strain BG1, a species of blue-green bacteria, was isolated by means of a nitrosoguanidine-penicillin procedure. Its growth characteristics were determined, and the enzymological block was identified in the A activity of tryptophan synthetase. Starvation of the auxotroph for tryptophan resulted in the derepression of the synthesis of all five enzymes. The first four enzymes derepressed 2- to 3-fold, and tryptophan synthetase B derepressed 20-fold. In the parental prototroph, BG1, anthranilate synthetase was active in crude extracts with ammonia as the amino donor reactant, but not with glutamine.
Mechanism of Inactivation of
Haemophilus influenzae
Transforming Deoxyribonucleic Acid by Sonic Radiation
Authors: Randolph M. L. , Setlow Jane K.
Published: January 2020

Transforming deoxyribonucleic acid (DNA) from
Haemophilus influenzae
was exposed to sonic radiation of various durations. Reductions in transforming ability of the DNA, cellular DNA uptake, and integration into the genome, and single- and double-stranded molecular weights of the transforming DNA were measured and compared. We conclude that (i) sonic radiation causes DNA strand breaks (almost always double-strand breaks with relatively few alkaline-labile bonds), the number increasing with exposure until the double-stranded molecular weight is reduced to less than 10
6
daltons; and (ii) since transformation is reduced about as much as integration and much more than uptake, inactivation of transforming DNA by sonic radiation appears to be caused mostly by failure of
Haemophilus
cells to integrate the transforming DNA that is taken into the cells. These results are similar to those for inactivation by X radiation but differ from those for ultraviolet radiation. A strand break caused by sonic radiation, however, does not necessarily inactivate the transforming DNA, whereas in the case of ionizing radiation it may. The results may be fit by the model proposed by Cato and Guild. From our data and the equation of Lacks, the minimum active site of DNA necessary for transformation and the frequency of exchanges between donor and recipient strands upon integration of transforming DNA were estimated as 0.35 × 10
6
to 0.7 × 10
6
daltons and 0.15 to 0.4 switches per 10
6
daltons, respectively.
Ribosomal Ribonucleic Acid Synthesis and Maturation in the Blue-Green Alga
Anacystis nidulans
Authors: Doolittle W. Ford
Published: January 2020

Methods are described for preparation of pulse-labeled ribonucleic acid (RNA) from the blue-green alga
Anacystis nidulans
. Synthesis of labeled RNA was found to be in part dependent on concurrent photosynthesis and was inhibited by the antibiotic streptolydigin. Mature 23
S
ribosomal RNA (rRNA) appeared before mature 16
S
rRNA. Formation of either molecule was inhibited by chloramphenicol, and RNA species of lesser mobility accumulated. These species may be precursors of the mature forms. Maturation of 16
S
rRNA was also inhibited by streptolydigin. (The effect of this antibiotic on 23
S
rRNA maturation was not examined). In many respects, ribosomal RNA synthesis and maturation in this blue-green alga appear to follow the pattern already established for bacteria.
Regulation of Homocysteine Biosynthesis in
Salmonella typhimurium
Authors: Savin Michael A. , Flavin Martin , Slaughter Clarence
Published: January 2020

The regulation of the homocysteine branch of the methionine biosynthetic pathway in
Salmonella typhimurium
has been reexamined with the aid of a new assay for the first enzyme. The activity of this enzyme is subject to synergistic feedback inhibition by methionine plus
S
-adenosylmethionine. The synthesis of all three enzymes of the pathway is regulated by noncoordinate repression. The enzymes are derepressed in
metJ
and
metK
regulatory mutants, suggesting the existence of regulatory elements common to all three. Experiments with a methionine/vitamin B
12
auxotroph (
metE
) grown in a chemostat on methionine or vitamin B
12
suggested that the first enzyme is more sensitive to repression by methionine derived from exogenous than from endogenous sources.
metB
and
metC
mutants grown on methionine in the chemostat did not show hypersensitivity to repression by exogenous methionine. Therefore, it appears that the
metE
chemostat findings are peculiar to the phenotype of this mutant; such evidence suggests a possible role for a functional methyltetrahydrofolate-homocysteine transmethylase in regulating the synthesis of the first enzyme. Thus there appear to be regulatory elements which are common to the repression of all three enzymes, as well as some that are unique to the first enzyme. The nature of the corepressor is not known, but it may be a derivative of
S
-adenosylmethionine.
metJ
and
metK
mutants of
Salmonella
have a normal capacity for
S
-adenosylmethionine synthesis but may be blocked in synthesis or utilization of a corepressor derived from it.
Superoxide Dismutase in
Bacillus popilliae
Authors: Costilow Ralph N. , Keele Bernard B.
Published: January 2020

Vegetative cells of
Bacillus popilliae
were devoid of catalase but had high levels of superoxide dismutase. This provides further support of a theory that oxygen tolerance by an organism is more dependent on superoxide dismutase than on catalase.
Isolation of Minicircular Deoxyribonucleic Acids from Wild Strains of
Escherichia coli
and their Relationship to other Bacterial Plasmids
Authors: Goebel Werner , Schrempf Hildgund
Published: January 2020

Supercoiled minicircular deoxyribonucleic acid (DNA) molecules with molecular weights of 1.8 × 10
6
and 2.3 × 10
6
have been isolated from two wild strains of
Escherichia coli
. DNA-DNA hybridization experiments indicate that these DNA molecules share extended homologies with the minicircular DNA of
E. coli
15. The DNA of the colicinogenic factor E1 (ColE1) also hybridizes to a large extent with minicircular DNA of
E. coli
15. In contrast, no hybridization could be detected with various large extrachromosomal DNA elements such as the colicinogenic factor V (ColV), the beta-hemolytic factor (Hly), or the P1-like DNA of
E. coli
15. Two different insertion DNA species of
E. coli
integrated into λdg-DNA (λdg UP
in
128, λdg UP
in
308) do not show any annealing with minicircular DNA of
E. coli
15.
Excision Repair Properties of Isogenic
rec
−
Mutants of
Escherichia coli
K-12
Authors: Shlaes David M. , Anderson Janet A. , Barbour Stephen D.
Published: January 2020

We have examined the excision repair properties of isogenic
rec
−
and
uvr
−
strains of
Escherichia coli
K-12. A
recB
−
recC
−
strain excises dimers at a rate nearly that of the
rec
+
parent, reaching the same extent of excision after a 1-hr postirradiation incubation.
recA
−
and
recA
−
recB
−
strains excise 75 to 80% of the dimers excised by their
rec
+
parent, whereas a
uvrB
−
strain excises no dimers during a 1-hr incubation. The doses of ultraviolet light (254 nm) required to reduce survival to 37% of the original population are 8 ergs/mm
2
for
recA
or
recA recB
mutants, 5 ergs/mm
2
for the
uvrB
−
strain, 30 ergs/mm
2
for the
recB recC
mutant, and 230 ergs/mm
2
for the wild-type parent. From these data one cannot account for the ultraviolet light sensitivity of
rec
−
strains on the basis of their excision repair properties. We conclude that
rec
gene products play no significant role in the early steps of excision repair. The assay we have used for excision of thymine dimers is a modification of the Carrier-Setlow technique, and is described in detail in the Appendix to this paper. To show the properties and validity of this method, results of experiments with thymine dimers formed in vitro and in vivo in
E. coli
K-12 are presented. These results show our method to be reproducible and sensitive to 0.005% of the total radioactive thymine present in thymine-containing dimers.
3′,5′-Cyclic Adenosine Monophosphate-Requiring Mutants of
Escherichia coli
Authors: Ohnishi Yoshinari , Silengo Lorenzo , Kuwano Michihiko , Schlessinger David
Published: January 2020

Mutants that require exogenous 3′,5′-cyclic adenosine monophosphate (cAMP) for exponential growth were isolated from strains deficient in adenyl cyclase. Studies of one strain showed that cAMP is not incorporated into macromolecules; instead, it seems to have a regulatory function, i.e., in media lacking cAMP, cells form ribonucleic acid (RNA) and protein at linear rather than exponential rates. The exact lesion is not known; ribosomes, messenger RNA, and the β and β′ subunits of RNA polymerase continue to be made in absence of added cAMP.
Genetic Transfer ofSalmonella typhimuriumandEscherichia coliLipopolysaccharide Antigens toEscherichia coliK-12
Authors: Jones Randall T. , Koeltzow Donald E. , Stocker B. A. D.
Published: January 2020

Escherichia coliK-12 ϰ971 was crossed with a smoothSalmonella typhimuriumdonor, HfrK6, which transfers early theilv-linkedrfaregion determining lipopolysaccharide (LPS) core structure. Twoilv+hybrids differing in their response to the LPS-specific phages FO and C21 were then crossed withS. typhimuriumHfrK9, which transfers early therfbgene cluster determining O repeat unit structure. Most recombinants selected forhis+(nearrfb) were agglutinated bySalmonellafactor 4 antiserum. Transfer of an F′ factor (FS400) carrying therfb–hisregion ofS. typhimuriumto the same twoilv+hybrids gave similar results. LPS extracted from twoilv+,his+, factor 4-positive hybrids contained abequose, the immunodominant sugar for factor 4 specificity. By contrast,his+hybrids obtained from ϰ971 itself by similar HfrK9 and F′FS400 crosses were not agglutinated by factor 4 antiserum, indicating that the parentalE. coliϰ971 does not have the capacity to attachSalmonellaO repeat units to its LPS core. It is concluded that theSalmonella rfbgenes are expressed only inE. coliϰ971 hybrids which have also acquiredilv-linked genes (presumablyrfagenes affecting core structure or O-translocase ability, or both) from aS. typhimuriumdonor. WhenE. coliϰ971 was crossed with a smoothE. colidonor, Hfr59, of serotype O8, which transfershisearly, mosthis+recombinants were agglutinated byE. coliO8 antiserum and lysed by the O8-specific phage, Ω8. This suggests that, although the parentalE. coliK-12 strain ϰ971 cannot attachSalmonella-specific repeat units to its LPS core, it does have the capacity to attachE. coliO8-specific repeat units.
Changes in Activity of Glyoxylate Cycle Enzymes During Myxospore Development in
Myxococcus xanthus
Authors: Orlowski Michael , Martin Presley , White David , Wong Michael Chi-Wai
Published: January 2020

Activities of the glyoxylate cycle enzymes isocitrate lyase (EC 4.1.3.1) and malate synthase (EC 4.1.3.2) were assayed in extracts prepared at different stages of myxospore formation in liquid cultures of
Myxococcus xanthus
. Activities of both enzymes attained peak values during conversion of rods to spheres. Isocitrate lyase activity decreased after reaching its peak value. Malate synthase activity also declined but at a much slower rate. The loss of isocitrate lyase activity could be prevented by the addition of chloramphenicol to cultures early in myxospore formation (during the initial rise in enzyme activity), but not by such addition at later stages of myxospore formation. The increase in glyoxylate cycle enzymes was not observed in a mutant unable to form myxospores in liquid culture under conditions suitable for morphological conversion of the wild type, or in wild-type cells incubated in the absence of an inducer for myxospore formation. It is concluded that the changes in the glyoxylate cycle enzymes represent regulatory phenomena associated with the development of the myxospore.
Antibody-Mediated Modification of the Binding Properties of a Protein Related to Galactose Transport
Authors: Rotman Boris , Ellis John H.
Published: January 2020

A galactose-binding protein related to the
mglP
transport system of
Escherichia coli
increases its affinity and binding capacity for the substrate when exposed to both
d
-galactose and specific antibodies. For this increase to occur, the binding protein has to be in contact with
d
-galactose for at least 2 min prior to the addition of the antibodies. This reaction was used to show that other substrates of the
mglP
transport system compete with galactose for a site(s) of the binding protein and that the degree of competition is comparable to that observed in vivo. A model for substrate translocation is presented postulating a cellular component that can induce conformational changes in the galactose-binding protein similar to those caused by antibodies.
Yeast Spheroplasts Formed by Cell Wall-Degrading Enzymes from
Oerskovia
sp
Authors: Mann J. W. , Heintz C. E. , Macmillan J. D.
Published: January 2020

Oerskovia
sp. produces inducible extracellular enzymes which degrade the walls of various yeasts. Yeast spheroplasts are formed from both log- and stationary-phase cells.
Repression of Enzymes of Arginine Biosynthesis by
l
-Canavanine in Arginyl-Transfer Ribonucleic Acid Synthetase Mutants of
Escherichia coli
Authors: Faanes Ronald , Rogers Palmer
Published: January 2020

We show that the arginine analogue,
l
-canavanine, repressed the accumulation of translatable messenger ribonucleic acid (RNA) for three arginine biosynthetic enzymes in
Escherichia coli
. The method used to determine the level of translatable messenger RNA depended upon measurement of a burst of enzyme synthesis as described previously.
E. coli
strains with defective arginyltransfer ribonucleic acid (tRNA) synthetase (
argS
mutants) were insensitive to canavanine repression. When deprived of leucine, a
leu argS
strain regained normal sensitivity to canavanine repression. The level of in vivo canavanyl-tRNA
arg
was determined for a normal strain and an
argS
mutant. After 20 min of growth with canavanine only 9% of tRNA
arg
from the
argS
strain was protected from periodate oxidation, while 42% of the tRNA
arg
from an
argS
+
strain was charged. When deprived of leucine,
leu argS
or
leu argS
+
strains grown with canavanine contained more than 60% charged tRNA
arg
. Reverse phase column chromatography of periodate-oxidized tRNA from canavanine-grown
argS
and
argS
+
strains showed no preferential charging of any isoaccepting species of tRNA
arg
. Therefore, we failed to detect a specific arginyl-tRNA species that might be involved in repression by canavanine. However, the data suggest that canavanine repression of the arginine pathway occurs only when high levels of canavanyl-tRNA are present, and thus support the notion that arginyl-tRNA synthetase plays a role in generating a repression signal.
Klebsiella aerogenes
Strain Carrying Drug-Resistance Determinants and a
lac
Plasmid
Authors: Brenchley Jean E. , Magasanik Boris
Published: January 2020

In addition to carrying determinants conferring resistance to at least two antibiotics, chloramphenicol and streptomycin, a
Klebsiella aerogenes
strain contains a plasmid responsible for increased β-galactosidase activity. The plasmid can be transferred to
Escherichia coli
and
Salmonella typhimurium
strains.
K. aerogenes
segregants without the plasmid grow on lactose one-half as fast as the parent strain and contain only one-tenth to one-fifth as much β-galactosidase.
Concerted Feedback Inhibition of the Aspartokinase ofRhodospirillum tenueby Threonine and Methionine: a Novel Pattern
Authors: Robert-Gero Malka , Borgne Lucien Le , Cohen Georges N.
Published: January 2020

The presence of a single aspartokinase was demonstrated inRhodospirillum tenue. The enzyme has been purified about 60-fold. No physical association exists in this species between aspartokinase and homoserine dehydrogenase. The general properties of the enzyme are described. Inhibition byl-lysine, byl-threonine, and concerted inhibition by these two end products are regulatory characters which have also been found in many other species. InR. tenue, aspartokinase is also subject to a hitherto not encountered type of concerted feedback inhibition, byl-threonine plusl-methionine. The inhibition caused by lysine can be reversed either by glycine,l-isoleucine,l-methionine, orl-phenylalanine. The concerted inhibition by lysine plus threonine is reversed by glycine,l-isoleucine, orl-phenylalanine, but not byl-methionine, which exerts in conjunction with threonine the independent concerted inhibition referred to above. Addition of single or several metabolites to cultures ofR. tenuecaused inhibition of growth and reversal of growth inhibition, compatible with the effects observed in vitro on aspartokinase activity. The regulation of this enzyme in relation to that of other bacterial aspartokinases is discussed.
Acetohydroxy Acid Synthetase with a
p
H Optimum of 7.5 from
Neurospora crassa
Mitochondria: Characterization and Partial Purification
Authors: Glatzer Louis , Eakin E. , Wagner R. P.
Published: January 2020

An acetohydroxy acid synthetase (AAS) has been found associated with the mitochondrial fraction of wild-type
Neurospora crassa
. It has a
p
H optimum of 7.5 and is presumed to be homologous to the
p
H 8.0 AAS that synthesizes the valine and isoleucine precursors in bacteria and yeast. The enzyme was characterized and purified 30- to 60-fold. The AAS activity of intact mitochondria requires thiamine pyrophosphate (TPP), Mn
2+
or Mg
2+
, and flavine adenine dinucleotide (FAD), and is sensitive to end product inhibition by
l
-valine. This inhibition is
p
H-dependent and noncompetitive with respect to pyruvate. Activity is slightly repressed during exponential growth in the presence of valine, isoleucine, and leucine. Extraction of the AAS from the mitochondria has a profound influence on the following properties:
p
H optimum, sensitivity to
l
-valine, response to FAD, binding of TPP, apparent
K
m
, and stability at 0 to 4 C. The catalytic properties of the partially purified enzyme are described. Two forms of the partially purified AAS can be isolated from preparative Sephadex G-200 chromatographic columns. Both forms are electrophoretically and antigenically similar but one form has an estimated molecular weight of 110,000 to 120,000 whereas the predominant form is a much larger and more buoyant molecule.
Competence Mutant of
Haemophilus influenzae
with Abnormal Ratios of Marker Efficiencies in Transformation
Authors: Caster John H. , Goodgal Sol H.
Published: January 2020

In studies of competence-deficient mutants of
Haemophilus influenzae
which absorb deoxyribonucleic acid (DNA) but fail to produce transformants, it was observed that in some mutants the residual transforming activity for different markers varied widely, i.e., produced a ratio effect. One of these mutants,
com
−56
, was studied intensively to determine the cause of the residual efficiency of transformation and the reason for the ratio effect. The residual frequency of transformation was higher for markers considered single-site mutations (like naladixic acid resistance), whereas the least efficient markers tested were those conferring resistance to high levels of streptomycin or novobiocin which are more complex than single-site mutations. Measurement of frequencies of cotransformation indicated that overall genetic linkage was reduced. Transfection was fairly efficient with phage S2 DNA, but not prophage DNA. Donor marker activity could be detected in transformed cell lysates, but not linked to recipient markers in recombinant molecules. Sucrose gradient analysis of such lysates revealed that donor material was associated with recipient DNA in at least normal quantities, but lacked detectable genetic activity. Material from donor DNA labeled with heavy isotopes was incorporated into recipient chromosomal fragments having a density indistinguishable from normal density, unlike the hybrid density recombinant material found in normal cells. No excessive solubilization or nicking of unincorporated donor was detected. It is postulated that this strain contains a hyperactive nuclease, which reduces the effective size of the input DNA during the integration process.
Specific Removal of Proteins from the Envelope of
Escherichia coli
by Protease Treatments
Authors: Inouye Masayori , Yee Mei-Lan
Published: January 2020

When the envelope fraction of
Escherichia coli
was treated by trypsin, about 40% of total envelope proteins were removed from the fraction without changing its phospholipid content. Analysis of envelope proteins by acrylamide gel electrophoresis in 0.5% sodium dodecyl sulfate revealed that trypsin treatment was very specific; one of the major proteins (molecular weight, 38,000) and all proteins of molecular weight greater than 70,000 were completely removed by the treatment. On the other hand, three other major proteins were found to be resistant to the treatment, including protein Y, which was previously shown to be related to deoxyribonucleic acid replication. The trypsin treatment of the envelope fractions composed of a five electron-dense layered structure formed vesicles with a triple-layered membrane (two electron-dense layers). Pronase treatment of the envelope fraction removed about 60% of the envelope proteins without changing its phospholipid content. A major protein of molecular weight of 58,000 was found to be the only protein resistant to the Pronase treatment. Application of these treatments is useful for purification and structural studies of envelope proteins.
Histidine Decarboxylaseless Mutants of
Lactobacillus
30a: Isolation and Growth Properties
Authors: Recsei Paul A. , Snell Esmond E.
Published: January 2020

Mutants of
Lactobacillus
30a deficient in their ability to form an inducible histidine decarboxylase (EC 4.1.1.22) were selected by plating nitrosoguanidine-treated cultures on a medium containing histidine and methyl red. Wild-type organisms produce histamine, thus raising the
p
H and forming yellow colonies; mutant colonies remain red. In the presence of added histidine, decarboxylase-producing cultures grow more heavily than mutant cultures when the initial
p
H of the growth medium is low or when the lactic acid produced lowers the
p
H to growth-limiting values. Addition of the decarboxylation products, histamine and carbon dioxide, did not favor growth in crude medium.
“Induction” of Colicin Factor E2-P9 by Mitomycin C
Authors: Hardy K. G. , Meynell G. G.
Published: January 2020

Mitomycin C increases the titers of colicin E2-P9 without increasing the amount of colicin factor deoxyribonucleic acid.
Temperature-Sensitive Osmotic Remedial Mutants of
Escherichia coli
Authors: Russell R. R. B.
Published: January 2020

A collection of temperature-sensitive mutants of
Escherichia coli
K-12 was examined for ability to grow at the restrictive temperature when the osmotic pressure of the medium was increased. Five of the fourteen mutants were found to be osmotic remedial. Four strains containing temperature-sensitive, osmotic-remedial mutations affecting aminoacyl-transfer ribonucleic acid synthetases were found to have altered permeability characteristics which may be attributable to changes in the lipopolysaccharide layer of the cell envelope at restrictive temperatures.
Phenotypic Suppression of Methicillin Resistance in
Staphylococcus aureus
by Mutant Noninducible Penicillinase Plasmids
Authors: Cohen Sidney , Gibson Carol J. , Sweeney H. M.
Published: January 2020

Methicillin (intrinsic) resistance of
Staphylococcus aureus
was suppressed almost completely by regulatory gene (
penI
1
) mutations of penicillinase plasmids that made penicillinase production strictly noninducible. Methicillin resistance was restored by secondary regulatory gene mutations that altered the noninducible phenotype or by complementation with a compatible plasmid that did not bear the noninducible mutation. No evidence was obtained for genetic linkage between a penicillinase plasmid and the gene for methicillin resistance. We suggest, therefore, that the mutant noninducible repressor acted in
trans
by binding to a site on the methicillin resistance determinant. This hypothesis would imply an appreciable degree of homology between penicillinase plasmids and methicillin resistance genes.
Self-Transfer and Genetic Recombination Mediated by P, the Sex Factor of
Vibrio cholerae
Authors: Parker Charlotte , Romig W. R.
Published: January 2020

Vibrio cholerae
cells, infected with the sex factor P, produce discrete, plaque-like clearings when plated on lawns of P
−
cells. We investigated the nature of these clearings and conclude that they are probably sites of active mating. We developed a quantitative assay for P
+
cells and used it to study the kinetics of sex factor spread in broth cultures. Both established and newly infected donor populations were efficient sex factor donors, indicating that P is not self-repressed. We also investigated the kinetics of recombinant formation in broth matings. In 1-hr matings, we routinely found recombination frequencies of 10
−6
per donor cell. Kinetic studies of recombinant formation showed that the markers tested all appeared at early times. Thus P, the
V. cholerae
sex factor, seems to resemble F in its transfer properties.
Genetic Studies on Plasmid-Linked Cadmium Resistance in
Staphylococcus aureus
Authors: Smith Katherine , Novick Richard P.
Published: January 2020

The genetic basis of cadmium resistance conferred by three penicillinase plasmids, PI
524
, PI
258
, and PII
147
, of
Staphylococcus aureus
was examined by mutation, recombination, and deletion analysis. Three separate loci were identified:
cadA
, responsible for high-level resistance;
cadB
, giving a low-level resistance, nonadditive to
cadA
; and
mad
, a locus marginally
decreasing
the cadmium resistance of plasmid-positive staphylococci. The loci
cadA
and
mad
were present on all three plasmids, but
cadB
was only found on PII
147
. Spontaneous deletions of
mad
involved up to three-fourths of the plasmid genome, which allowed derivation of a partial deletion map of PII
147
, a plasmid with a contour length of 10.9 μm, corresponding to a molecular weight of 20.4 × 10
6
.
Mapping of the Tryptophan Genes of
Acinetobacter calcoaceticus
by Transformation
Authors: Sawula R. V. , Crawford Irving P.
Published: January 2020

Auxotrophs of
Acinetobacter calcoaceticus
blocked in each reaction of the synthetic pathway from chorismic acid to tryptophan were obtained after
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine mutagenesis. One novel class was found to be blocked in both anthranilate and
p
-aminobenzoate synthesis; these mutants (
trpG
) require
p
-aminobenzoate or folate as well as tryptophan (or anthranilate) for growth. The loci of six other auxotrophic classes requiring only tryptophan were defined by growth, accumulation, and enzymatic analysis where appropriate. The
trp
mutations map in three chromosomal locations. One group contains
trpC
and
trpD
(indoleglycerol phosphate synthetase and phosphoribosyl transferase) in addition to
trpG
mutations; this group is closely linked to a locus conferring a glutamate requirement. Another cluster contains
trpA
and
trpB
, coding for the two tryptophan synthetase (EC 4.2.1.20) subunits, along with
trpF
(phosphoribosylanthranilate isomerase); this group is weakly linked to a
his
marker. The
trpE
gene, coding for the large subunit of anthranilate synthetase, is unlinked to any of the above. This chromosomal distribution of the
trp
genes has not been observed in other organisms.
Myxobacter AL-1 Protease II: Specific Peptide Bond Cleavage on the Amino Side of Lysine
Authors: Wingard Marilyn , Matsueda Gary , Wolfe R. S.
Published: January 2020

A second extracellular protease from myxobacter strain AL-1 has been purified to homogeneity and named protease II; the enzyme crystallizes as fine needles. The extracellular, cell wall lytic protease reported previously from the same organism is now designated protease I. Protease II exhibits a
p
H optimum of 8.5 to 9.0 and is stable from
p
H 3.0 to 9.0. The enzyme is heat stable at 50 C for 18 hr. Results of sedimentation equilibrium studies yielded a molecular weight of 17,000, and amino acid analysis revealed 157 residues with a minimal molecular weight of 16,660. Cleavage of peptide bonds in the oxidized B-chain of insulin, cytochrome
c
(horse heart). lysozyme, and vasopressin is restricted to the amino side of lysine. Dilysine and trilysine were not hydrolyzed. Products from digestions of polylysine were lysine and dilysine.
Effect of the Proline Analogue Baikiain on Proline Metabolism in
Salmonella typhimurium
Authors: Dendinger Susan , Brill Winston J.
Published: January 2020

A proline analogue, 4,5-dehydro-
l
-pipecolic acid (baikiain) induces the formation in
Salmonella typhimurium
of the two enzymes catalyzing the degradation of proline, proline oxidase and Δ
1
-pyrroline-5-carboxylic acid (P5C) dehydrogenase. The level of induction by 20 m
m
baikiain is about 10% of the maximum level induced by proline. Since the analogue is a substrate of proline oxidase the first enzyme of the proline catabolic pathway, the oxidation derivative rather than baikiain itself might be the actual effector. Baikiain is also an inducer of proline oxidase in
Escherichia coli
K-12 and
E. coli
W. An additional effect of this analogue on proline degradation in
S. typhimurium
is inhibition of P5C dehydrogenase. At a concentration of 5 × 10
−4
m
, baikiain inhibits completely the growth of strains constitutive for proline oxidase. This inhibition, which can be overcome by proline, occurs in the presence or absence of P5C dehydrogenase activity. Three spontaneously occurring mutants resistant to baikiain were isolated from constitutive strains. All are pleiotropic-negative for the proline-degrading enzymes. The sites of these mutations are linked to the
put
region. Although the mechanism of toxicity has not been determined, baikiain provides a simple and direct selection for obtaining mutants unable to degrade proline. In addition, it allows selection for strains with an inducible rather than constitutive phenotype.
Mutant of
Escherichia coli
with Derepressed Levels of the Biotin Biosynthetic Enzymes
Authors: Pai C. H.
Published: January 2020

A cross-feeding technique was used to isolate a mutant of
Escherichia coli
K-12 that excretes 1,000 times more biotin into the growth medium than the parent strain. The mutant has high levels of the biotin biosynthetic enzymes even when grown in the presence of biotin. Desthiobiotin synthetase, the level of which was used as a measure of the biosynthetic activity of the biotin pathway, is not repressed by biotin at the concentration 250,000 times that sufficient to repress the enzyme in the wild type. The mutant gene is cotransducible with
argC
located at 77 min on the
E. coli
chromosome.
Isolation of Polyisoprenyl Alcohols from
Streptococcus faecalis
Authors: Umbreit Jay N. , Stone K. John , Strominger Jack L.
Published: January 2020

C
55
-isoprenyl alcohol and its derivatives have been isolated from
Streptococcus faecalis
and characterized. The relative amounts present as free alcohol, neutral lipid esters, and phosphate ester derivatives were determined. The chain lengths, mass spectra, and
cis
to
trans
ratio of double bonds are reported.
Membrane Association of the Deoxyribonucleic Acid Growing-Point Region in
Mycoplasma gallisepticum
Authors: Quinlan Dennis C. , Maniloff Jack
Published: January 2020

Newly replicated deoxyribonucleic acid (DNA) in
Mycoplasma gallisepticum
A5969 is membrane associated. Cells pulse-labeled 1 to 3 min with
3
H-thymidine are lysed by a freeze-thaw procedure. After brief sonic treatment to shear the DNA, differential centrifugation gives a cell fraction (P2) that is enriched sevenfold for pulse-labeled DNA. P2 contains 80% of the total adenosine triphosphatase activity, 65% of the total cholesterol, and morphologically intact terminal bleb structures. Three to four minutes are needed to fully label the DNA growing-point region, whereas 7 to 8 min are required to “chase” 50% of the
3
H-labeled DNA. This pulse-chase removes 80 to 85% of the nascent DNA from the P2 fraction.
Pattern of Replication of a Colicin Factor During the Cell Cycle of
Escherichia coli
Authors: Zeuthen J. , Morozow E. , Pato M. L.
Published: January 2020

The ColBM,
trp, lac
episome was transferred to a
lacZ
derivative of
Escherichia coli
B/r, and the manner of replication of this colicinogenic factor was followed through the cell cycle. The results suggest a pattern of replication not connected with any particular stage in the cell cycle.
Ribosomes, Polyribosomes, and Deoxyribonucleic Acid from Thermophilic, Mesophilic, and Psychrophilic Clostridia
Authors: Irwin Carol C. , Akagi James M. , Himes Richard H.
Published: January 2020

Analysis of deoxyribonucleic acid (DNA) from four species of
Clostridium
, including two thermophiles, a mesophile, and a psychrophile, revealed no obvious relationship between growth temperature and DNA base composition. The melting temperatures (T
m
) of the DNA from the four species varied no more among the thermophilic, mesophilic, and psychrophilic species than among many related mesophilic species. Characterization of ribosomes from the clostridia by means of optical rotatory dispersion yielded similar spectra in common with other unrelated organisms. Only small differences were noted in the base composition of ribosomal ribonucleic acid (RNA) and in the amino acid composition of ribosomal proteins, including half-cystine content, as determined by cysteic acid analysis, and accessible sulfhydryl groups, as determined by titration with dithiobis (2-nitrobenzoic acid). Except for the two thermophiles, the ribosomal protein electrophoretic patterns were dissimilar. No unusual thermal stability was manifested in the T
m
values of thermophile ribosomal RNA. However, thermophile ribosome T
m
values (69 C) were higher than were mesophile and psychrophile T
m
values (64 C). Ribosomes from the four clostridial species were also examined in regard to the effect of heat on their functional integrity, measured by their activity in poly U-directed
14
C-phenylaline incorporation, and their gross physical integrity, measured by sucrose gradient analysis. The T
d, 5
values (temperature which produces 50% inactivation after 5 min) was found to be 70 and 72 C for the two thermophiles
C. tartarivorum
and
C. thermosaccharolyticum
, respectively; 57 C for a mesophile,
C. pasteurianum
; and 53 C for a psychrophile,
Clostridium
sp. strain 69. At 55 C, little effect was seen on the thermophile ribosomes, but the mesophile ribosomes lost 90% of their activity in 1 hr, and psychrophile ribosomes lost 100% of their activity within 10 min. According to sucrose gradient profiles, heating at 55 C results in dissociation of mesophile ribosomes and aggregation of psychrophile ribosomes. Thermophile S-100 fractions were also more thermostable than were mesophile or psychrophile S-100 fractions. The T
d, 5
values were 69 C for
C. tartarivorum
and
C. thermosaccharolyticum
S-100 and 41 C for
C. pasteurianum
and
Clostridium sp.
strain 69 S-100. The effect of heat on the endogenous incorporation of
14
C-valine by polysomes was also examined. In the case of thermophile polysomes, the extent of incorporation at 55 and 37 C was about equal. In the case of mesophile and psychrophile polysomes, the extent at 55 C was 44 and 39%, respectively, of the value at 37 C. The initial rates of incorporation in all four cases were greater at 55 C than at 37 C.
Regulation of Flagellar Morphogenesis by Temperature: Involvement of the Bacterial Cell Surface in the Synthesis of Flagellin and the Flagellum
Authors: McGroarty Estelle J. , Koffler Henry , Smith R. W.
Published: January 2020

When cells of
Proteus vulgaris
were transferred from 37 to 42 C, a temperature at which they continue to grow almost optimally, they ceased to form flagella after approximately one generation time. This failure was due to a lesion in the flagellin-synthesizing process rather than the inability of these cells to assemble the organelle from constituents once formed. After transfer back to 37 C, these cells regained their ability to synthesize flagellin and form flagella, after one generation. When added during this period, chloramphenicol, rifampin, or penicillin prevented the synthesis of flagellin. The regeneration of the organelle at 37 C, then, requires growth for one generation, a period during which not only ribonucleic acid and protein synthesis, but also the presence of an intact cell envelope or concurrent synthesis of cell wall, are required.
Comparative Transport Activity of Intact Cells, Membrane Vesicles, and Mesosomes of
Bacillus licheniformis
Authors: MacLeod Robert A. , Thurman Paul , Rogers H. J.
Published: January 2020

Sodium ion was shown to stimulate strongly the transport of
l
-glutamic acid into cells of
Bacillus licheniformis
6346 His
−
. Lithium ion had a slight capacity to replace Na
+
in this capacity, but K
+
was without effect. Three of five amino acids tested.
l
-glutamic acid,
l
-aspartic acid, and
l
-alanine, were concentrated against a gradient in the cells. Intracellular pools of these amino acids were extractable with 5% trichloroacetic acid. Pools of
l
-histidine and
l
-lysine could not be detected. No evidence of active transport of lysine into cells could be detected, and histidine was taken up in the absence of chloramphenicol but not in its presence. The uptake of glutamic acid by membrane vesicle preparations was strongly stimulated by reduced nicotinamide adenine dinucleotide (NADH) and to a lesser extent by succinate. The presence of phenazine methosulfate increased uptake in the presence of succinate. Either
l
- or
d
-lactate and adenosine triphosphate were without effect. None of these compounds stimulated the uptake of glutamic acid by mesosomes, although some mesosome preparations contained separable membrane which was very active. NADH strongly stimulated the uptake of aspartic acid and alanine by membrane vesicles but had only a slight effect on the uptake of histidine and lysine. No evidence of active transport of any of the amino acids into mesosomes could be detected either in the presence or absence of NADH. NADH stimulation of the uptake of glutamic acid by membrane vesicles was destroyed by exposure to light of 360 nm; this inactivation was reversible by vitamin K

2
(5)

or K

2
(10)

. Sodium ion stimulated transport of glutamic acid by membrane vesicles.
Comparative Studies on the Isolation of Membrane Lipoteichoic Acid fromLactobacillus fermenti
Authors: Wicken A. J. , Gibbens Janet W. , Knox K. W.
Published: January 2020

Preparations of membrane lipoteichoic acid containing different amounts of protein were isolated from intact organisms ofLactobacillus fermentiNCTC 6991 by various procedures chosen for their ability to disrupt the hydrophobic interaction of lipoteichoic acid with other membrane components. The highest yield of lipoteichoic acid was obtained with hot aqueous phenol, and this preparation contained very little protein. Partial removal of cell lipids with chloroform-methanol followed by extraction with water at 100 C gave a lipoteichoic acid-protein complex that was a very effective immunogen; immunogenicity was shown to relate to protein content, though the specificity of the antibodies was directed against the teichoic acid component.
Ultrastructure of Free-Living and Nitrogen-Fixing Forms of
Rhizobium meliloti
as Revealed by Freeze-Etching
Authors: MacKenzie C. R. , Vail W. J. , Jordan D. C.
Published: January 2020

Freeze-etching of
Rhizobium meliloti
provided considerable insight into the ultrastructure of this bacterium and into the changes accompanying the transformation from the free-living rod forms to the nitrogen-fixing bacteroid forms. In the small rods, one cleavage plane was revealed at the level of the cell wall and a second at the level of the plasma membrane. Very little structure was evident at the cell wall level, but distinctly different convex and concave fracture faces were exposed at the cell membrane cleavage plane. During the transformation into the bacteroidal state the wall decreased in thickness, became less rigid, and developed a particulate surface. In addition, changes in particle density were observed in the plasma membrane. The fine structure of the plant membranes, the infection threads, and the arrangement of the bacteroids within the plant cells also were revealed.
Freeze-Etch Study of
Pseudomonas aeruginosa
: Localization Within the Cell Wall of an Ethylenediaminetetraacetate-Extractable Component
Authors: Gilleland H. E. , Stinnett J. D. , Roth I. L. , Eagon R. G.
Published: January 2020

A freeze-etch study of normal cells of
Pseudomonas aeruginosa
and of cells after incubation with ethylenediaminetetraacetate (EDTA) and tris(hydroxymethyl)aminomethane (Tris) was performed. When cells were freeze-etched without a cryoprotective agent, a smooth outer cell wall layer, which showed a regular array of subunits, and the presence of flagella and pili were observed. These features were not observed in cells freeze-etched after cryoprotection with glycerol. Four fracture surfaces, which resulted from splitting down the center of the outer wall membrane and of the inner cytoplasmic membrane, were revealed in freeze-etched glycerol-protected cells. The murein layer was seen in profile between the outer cell wall membrane and the cytoplasmic membrane. Spherical units and small rods composed of the spherical units were observed in the inner layer of the outer cell wall membrane. These spherical units appeared to be attached to, or embedded in, the inner face of the outer layer of the outer cell wall membrane. These spherical units were removed from cells on exposure to EDTA-Tris, resulting in cells that were osmotically fragile. The spherical units were detected via electron microscopy of negatively stained preparations in the supernatant fluid of cellular suspensions treated with EDTA-Tris. Upon addition of Mg
2+
, the spherical units were reaggregated into the inner layer of the outer cell wall membrane and the cells were restored to osmotic stability. The spherical units were shown to consist primarily of protein. These data are thought to represent the first ultrastructural demonstration of reaggregation of cell wall components within a living cell system.
Autolysis of
Listeria monocytogenes
Authors: Tyrrell E. A.
Published: January 2020

Autolytic curves of five representative strains of
Listeria monocytogenes
are described. Of 24 strains so far examined, the majority are unstable in vitro.
Morphology and Ultrastructure of Staphylococcal L Colonies: Light, Scanning, and Transmission Electron Microscopy
Authors: Fass Robert J.
Published: January 2020

Scanning electron microscopy utilizing critical point drying was used in parallel with light and transmission electron microscopy to study L colonies produced by a stable L-phase variant of
Staphylococcus aureus
(AH24H).
Surface Distribution of Invertase on Growing
Saccharomyces
Cells
Authors: Tkacz J. S. , Lampen J. O.
Published: January 2020

By using fluorescein-labeled antibodies, we found that most of the newly formed invertase molecules at the surface of a
Saccharomyces
cell surround the developing bud.
Occurrence of Glucosamine Residues with Free Amino Groups in Cell Wall Peptidoglycan from Bacilli as a Factor Responsible for Resistance to Lysozyme
Authors: Hayashi Hideyuki , Araki Yoshio , Ito Eiji
Published: January 2020

Analysis by dinitrophenylation techniques revealed the occurrence of significant amounts of glucosamine residues with free amino groups in the peptidoglycan component of cell walls isolated fromBacillus cereus, Bacillus subtilis, andBacillus megaterium. A close correlation was demonstrated between the content ofN-unacetylated glucosamine residues in the peptidoglycan component and the resistance of the cell walls to lysozyme. These lysozyme-resistant cell walls and peptidoglycan were converted into a lysozyme-sensitive form by means ofN-acetylation with acetic anhydride. Thus, the occurrence of theN-unacetylated glucosamine residues in the peptidoglycan component accounts for the resistance of these cell walls to lysozyme. TheN-unacetylated glucosamine residues were not found in a significant amount in the cell walls ofMicrococcus lysodeikticus, Staphylococcus aureus, Streptococcus faecalis, Lactobacillus casei, orLactobacillus arabinosus.