bluuebunny/crossref_metadata_2025 huggingface dataset:
Stereospecificity of Tripeptide Utilization in a Methionine Auxotroph ofEscherichia coliK-12
Authors: Becker Jeffrey M. , Naider Fred
Published: January 2020

The stereospecificity of peptide utilization inEscherichia coliK-12 4212, a methionine auxotroph, was investigated using diastereomers of trimethionine and trimethionine methyl ester. Of the eight stereoisomers examined, onlyl-Met-l-Met-l-Met,l-Met-l-Met-d-Met, andd-Met-l-Met-l-Met and the corresponding methyl esters serve as growth substrates. Triornithine-resistant mutants of strain 4212 were isolated which failed to transportd-Met-l-Met-l-Met. These results provide evidence that an oligopeptide containing adresidue at its amine terminus can enterE. coliby the oligopeptide transport system.
Mechanism of Energy Coupling For Transport of
d
-Ribose in
Escherichia coli
Authors: Curtis Susan J.
Published: January 2020

In
Escherichia coli
ML 308-225,
d
-ribose is transported into the cell by a constitutive active transport system of high activity. The activity of this transport system is severely reduced in cells subjected to osmotic shock, and the system is not present in membrane vesicles. The mechanism by which metabolic energy is coupled to transport of ribose was investigated. Substrates which generate adenosine 5′-triphosphate primarily through oxidative phosphorylation are poor energy sources for ribose uptake in DL-54, a mutant of ML 308-225 which lacks activity for the membrane-bound Ca
2+
, Mg
2+
-dependent adenosine triphosphatase required for oxidative phosphorylation. Arsenate severely inhibits ribose uptake, whereas, under the same conditions, uptake of
l
-proline is relatively insensitive to arsenate. Anaerobiosis does not significantly inhibit ribose uptake in ML 308-225 or DL-54 when glucose is the energy source. A significant amount of ribose uptake is resistant to uncouplers of oxidative phosphorylation such as 2,4-dinitrophenol. These results indicate that the phosphate bond energy of adenosine 5′-triphosphate, rather than an energized membrane state, couples energy to ribose transport in ML 308-225.
Chloroplast and Cytoplasmic Ribosomes of
Euglena
: Selective Binding of Dihydrostreptomycin to Chloroplast Ribosomes
Authors: Schwartzbach Steven D. , Schiff Jerome A.
Published: January 2020

Dihydrostreptomycin binds preferentially to chloroplast ribosomes of wild-type
Euglena gracilis
Klebs var.
bacillaris
Pringsheim. The

K
diss

for the wild-type chloroplast ribosome-dihydrostreptomycin complex is 2 × 10
−7
M, a value comparable with that found for the
Escherichia coli
ribosome-dihydrostreptomycin complex. Chloroplast ribosomes isolated from the streptomycin-resistant mutant Sm
1
r
BNgL and cytoplasmic ribosomes from wild-type have a much lower affinity for the antibiotic. The

K
diss

for the chloroplast ribosome-dihydrostreptomycin complex of Sm
1
r
is 387 × 10
−7
M, and the value for the cytoplasmic ribosome-dihydrostreptomycin complex of the wild type is 1,400 × 10
−7
M. Streptomycin competes with dihydrostreptomycin for the chloroplast ribosome binding site, and preincubation of streptomycin with hydroxylamine prevents the binding of streptomycin to the chloroplast ribosome. These results indicate that the inhibition of chloroplast development and replication in
Euglena
by streptomycin and dihydrostreptomycin is related to the specific inhibition of protein synthesis on the chloroplast ribosomes of
Euglena
.
Cell Wall Polymers of
Bacillus sphaericus
: Activities of Enzymes Involved in Peptidoglycan Precursor Synthesis During Sporulation
Authors: Linnett Paul E. , Tipper Donald J.
Published: January 2020

In synchronously sporulating cells of
Bacillus sphaericus
9602, the specific activities of those enzymes specifically required for the synthesis of the UDP-
N
-acetyl-muramyl-pentapeptide precursor of vegetative cell wall peptidoglycan decay by 50% after the end of exponential cell division, probably as a consequence of dilution by newly synthesized protein. The
meso
-diaminopimelate ligase is the only new activity whose synthesis is required for synthesis of the nucleotide-pentapeptide precursor of spore cortex peptidoglycan. The addition of
d
-Ala-
d
-Ala to the nucleotide tripeptide is catalyzed by an enzyme present in both vegetative and sporulating cells, which apparently does not discriminate between lysine- and diaminopimelate-containing acceptors. The activities of the
l
-Ala and
d
-Ala-
d
-Ala ligases and of the
d
-Ala-
d
-Ala synthetase increases in parallel with the appearance of the diaminopimelate ligase, indicating coordinate derepression and suggesting operon-like organization of the appropriate structural genes.
Genetic Mapping of the Antigenic Determinants of Two Polysaccharide K Antigens, K10 and K54, in
Escherichia coli
Authors: Ørskov Ida , Nyman Kate
Published: January 2020

The genes controlling synthesis of the
Escherichia coli
acidic polysaccharide capsular antigens K10 and K54 were transferred by conjugation to
E. coli
strains of other serotypes. The genes concerned with these K antigen determinants showed genetic linkage with the
serA
locus. We propose to name the K antigen-controlling gene
kpsA
. The genetic determinants of the two K antigens could also be transferred to enteropathogenic serotypes, even though such strains have never been found in nature with special acidic polysaccharide K antigens. A noncapsulated derivative, K
−
, of the K10 strain can transfer the genetic determinant of the K antigen, demonstrating the probable existence of another chromosomal locus involved in the production of such acidic polysaccharide K antigens.
Active Transport of Exogenous
S
-Adenosylmethionine and Related Compounds into Cells and Vacuoles of
Saccharomyces cerevisiae
Authors: Nakamura K. D. , Schlenk F.
Published: January 2020

Saccharomyces cerevisiae
4094-B (α,
ade-2, ura-1
) in potassium phosphate buffer with glucose under aerobic conditions took up (−)
S
-adenosyl-
l
-methionine from the medium in sufficient quantity to permit the demonstration of its accumulation in the vacuole by ultraviolet micrography. The same result was obtained with (±)
S
-adenosyl-
l
-methionine, (±)
S
-adenosyl-
d
-methionine, and (−)
S
-adenosyl-
l
-ethionine. The rate of uptake was slow with (−)
S
-adenosyl-
S
(
n
-propyl)-
l
-homocysteine and
S
-adenosyl-
d
-homocysteine.
S
-Adenosyl-
l
-homocysteine was assimilated rapidly, but intracellular degradation precluded accumulation and ultraviolet micrographic studies. The uptake of 5′-methyl-, 5′-ethyl-, 5′-
n
-propylthioadenosine, and 5′-dimethylsulfonium adenosine was minimal.
Small-Cell Formation of
Staphylococcus aureus
by Subinhibitory Concentrations of Nitrofuran Derivatives
Authors: Koike Masaatsu , Iida Kyoko , Nakashima Koichi , Tokunaga Junichi
Published: January 2020

Small-cell formation of
Staphylococcus aureus
by subinhibitory concentration of nitrofuran derivatives was examined by scanning and transparent electron microscopy.
Subcellular Localization of Isoleucine-Valine Biosynthetic Enzymes in Yeast
Authors: Ryan E. D. , Kohlhaw G. B.
Published: January 2020

By using the method of stepwise homogenization of yeast spheroplast lysates employed previously with the leucine biosynthetic enzymes, it is shown that threonine deaminase, acetohydroxy acid synthase, Mg
2+
-dependent isomero-reductase, and dihydroxy acid dehydratase are particulate. Density gradient centrifugation and the behavior of marker enzymes suggest that all of the above enzymes of the isoleucine-valine biosynthetic pathway are associated with the mitochondria.
Isoleucine and Valine Metabolism inEscherichia coliK-12: Detection and Measurement ofilv-Specific Messenger Ribonucleic Acid
Authors: Haar R. A. Vonder , Umbarger H. E.
Published: January 2020

Ribonucleic acid-deoxyribonucleic acid (RNA-DNA) hybridization was employed for the determination of messenger RNA transcribed from theilvgene cluster ofEscherichia coliK-12. Strains with derepressed levels of the isoleucine and valine biosynthetic enzymes owing to linked or unlinked genetic lesions were found to exhibitilvmessenger RNA levels from 1.5- to 4-fold higher than did their isogenic parents. When grown under conditions that specifically repressed the synthesis of isoleucine- and valine-forming enzymes, most strains exhibited drastically reducedilvmessenger RNA levels. Hybridization performed with the separated strands ofilvDNA showed that all theilvgenes are transcribed from the same strand, the “lstrand” of λφ80CI857St68dilvDNA. Sucrose gradient analyses of RNA extracted from cells starved for isoleucine, valine, or leucine resulted in the detection of at least two distinct types ofilvmessenger RNA.
Characterization of a Bacteriophage-Induced, Host-Specific Lytic Enzyme from Lysates of
Bacillus stearothermophilus
Infected with Bacteriophage TP-8
Authors: Brehm Sylvia P. , Welker N. E.
Published: January 2020

Phage TP-8 lysates of
Bacillus stearothermophilus
4S or 4S(8) contain lytic activity exhibiting two pH optima, one at pH 6.5 and the other at pH 7.5. Using a variety of fractionation procedures, the two lytic activities could not be separated. At pH 7.5 the lytic enzyme is an endopeptidase which hydrolyzes the
l
-alanyl-
d
-glutamyl linkage in the peptide subunits of the cell wall peptidoglycan and at pH 6.5 it exhibits
N
-acetylmuramidase activity. Endopeptidase activity is inhibited by NaCl and neither lytic activity was significantly affected by divalent cations or ethylenediaminetetraacetic acid. Crude lysates contain 2.5 to 3.0 times more endopeptidase activity than
N
-acetylmuramidase activity. The ratio of the two lytic activities (endopeptidase/
N
-acetylmuramidase) changes to 1.3 to 1.7 during the course of purification, to 1.0 after isoelectric focusing, and 3.9 and 6.00 after exposure for 2 h at 60 and 65 C, respectively. We conclude that the two lytic activities may be associated with a single protein or a lytic enzyme complex composed of two enzymes. Lytic activity at pH 7.5 is more effective in solubilizing cells or cell walls than the lytic activity at pH 6.5. LiCl extracts of 4S and 4S(8) cells contain lytic activity exhibiting endopeptidase activity at pH 7.5 and
N
-acetylmuramidase activity at pH 6.5. Lytic activity in these LiCl extracts also has a number of other properties in common with those in lysates of phage TP-8. We proposed that the lytic enzyme(s) are not coded for by the phage genome but are part of the host autolytic system.
Properties of Thermosensitive Extracellular α-Amylases of
Bacillus subtilis
Authors: Yamane Kunio , Maruo Bunji
Published: January 2020

Enzymological properties of four thermosensitive α-amylases (M3, M9, M18, and M20) brought by different mutation sites in α-amylase structural gene of
Bacillus subtilis
were compared with those of the parental α-amylase NA64. Two thermosensitive α-amylases (M9 and M20) were altered not only in their thermosensitivity but also in their immunological properties, catalytic properties, molecular weights determined by the gel filtration on a Bio-Gel P-100 column, and others. The other two thermosensitive α-amylases (M3 and M18) were altered only in their thermosensitivity.
Nature of Ribonucleic Acid Synthesis During Early Sporulation in
Saccharomyces cerevisiae
Authors: Chaffin W. L. , Sogin S. J. , Halvorson H. O.
Published: January 2020

Phosphate uptake in sporulating cultures of
Saccharomyces cerevisiae
has been found to occur approximately 2 h after the transfer to sporulation medium. Early ribonucleic acid synthesis begins at approximately 4 h and continues to 8 h. Incorporation of phosphate into acid-extractable precursor pools parallels phosphate uptake. In triple-labeling experiments it was observed that the breakdown of vegetatively synthesized ribonucleic acid is not a significant source of precursors for ribonucleic acid synthesis during sporulation. The majority of the ribonucleic acid made in a 10-min period during sporulation does not migrate on gels with precursor or mature ribosomal ribonucleic acid.
his-Linked Hydrogen Sulfide Locus in Salmonella typhimurium
Authors: Voll Mary J. , Shiller Lynn M. , Castrilli Joanne
Published: January 2020

Investigation of strains of
Salmonella typhimurium
having extended
his
deletion mutations indicates that a genetic site (or sites) affecting H
2
S production is located in the region of the chromosome adjacent to the operator end of the
his
operon. This site is co-transducible with the
his
genes. Experimental data indicate that the site is also present on an F'
his
factor derived from
S. typhimurium
, FS401. Evidence is presented for the existence of another site affecting H
2
S production which is not linked to
his
.
Protein and Carbohydrate Composition of the Cell Envelope of
Halobacterium salinarium
Authors: Mescher M. F. , Strominger J. L. , Watson S. W.
Published: January 2020

The isolated cell envelope of
Halobacterium salinarium
strain 1 contained 15 to 20 proteins that were resolved by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. All but one of these proteins had molecular weights of 130,000 or less and together accounted for 50 to 60% of the total envelope protein. The remaining 40 to 50% of the envelope protein was accounted for by a single protein with an apparent molecular weight of approximately 194,000 that stained for carbohydrate with periodate-Schiff reagent. The proteolytic enzymes trypsin and Pronase were used to show that the carbohydrate is covalently bound to the protein. Separation of amino sugar- and hexose-containing tryptic peptides by gel filtration indicated that all of the nonlipid carbohydrate of the cell envelope is covalently bound to protein. The results of partial purification by phenol extraction indicated that both the amino sugar and hexose are bound to the 194,000-molecular-weight protein. Exposure of isolated cell envelopes to low salt concentration resulted in solubilization of a majority of the envelope proteins. A relatively small number of proteins, including the high-molecular-weight, carbohydrate-containing protein, remained bound to the sedimentable cell membrane fraction.
Purification and Characterization of the
Pseudomonas multivorans
Glucose-6-Phosphate Dehydrogenase Active with Nicotinamide Adenine Dinucleotide
Authors: Wyk J. C. Vander , Lessie T. G.
Published: January 2020

The
Pseudomonas multivorans
glucose-6-phosphate dehydrogenase (EC 1.1.1.49) active with nicotinamide adenine dinucleotide, which is inhibitable by adenosine-5'-triphosphate, was purified approximately 1,000-fold from extracts of glucose-grown bacteria, and characterized with respect to subunit composition, response to different inhibitory ligands, and certain other properties. The enzyme was found to be an oligomer composed of four subunits of about 60,000 molecular weight. Reduced nicotinamide adenine dinucleotide phosphate, but not reduced nicotinamide adenine dinucleotide, was found to be a potent inhibitor of its activity. The range of concentrations of reduced nicotinamide adenine dinucleotide phosphate over which inhibition occurred was about 100-fold lower than that for adenosine-5'-triphosphate. The data suggest that reduced nicotinamide adenine dinucleotide phosphate may play an important role in regulation of hexose phosphate metabolism in
P. multivorans
. Antisera prepared against the purified enzyme strongly inhibited its activity, but failed to inhibit the activity of the nicotinamide adenine dinucleotide phosphate-specific glucose-6-phosphate dehydrogenase which is also present in extracts of this bacterium. Immunodiffusion experiments confirmed the results of the enzyme inhibition studies, and failed to support the idea that the two glucose-6-phosphate dehydrogenase species from
P. multivorans
represent different oligomeric forms of the same protein.
Comparative Studies on Induction of Sporulation and Synthesis of Inducible Enzymes in
Bacillus subtilis
Authors: Coote J. G.
Published: January 2020

An attempt was made to determine whether sporulation and inducible enzyme synthesis in
Bacillus subtilis
are controlled by the same mechanism of catabolite repression. By the use of a thymine-requiring strain, it has been shown that, whereas sporulation remained repressed unless chromosome replication proceeded to completion, the induction of the enzymes histidase, sucrase, and α-glucosidase proceeded quite normally in the absence of continued deoxyribonucleic acid synthesis. It is concluded that the mechanism for overcoming the repression of sporulation differs qualitatively from that involved in overcoming the repression of inducible enzyme synthesis. Attempts to isolate pleiotropic mutants that would provide additional support for this contention were unsuccessful. A pleiotropic mutant deficient in phosphoenolpyruvate-dependent phosphotransferase activity sporulated quite well, whereas a mutant presumed deficient in glutamate synthetase sporulated poorly under all conditions.
Existence of a Free Form of a Specific Membrane Lipoprotein in Gram-Negative Bacteria
Authors: Halegoua Simon , Hirashima Akikazu , Inouye Masayori
Published: January 2020

The existence of a free form of a specific lipoprotein of molecular weight 7,200 was examined in the envelopes of several gram-negative bacteria. When the envelope proteins were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, distinct peaks were observed in
Salmonella typhimurium, Serratia marcescens
, and
Pseudomonas aeruginosa
at the same position as the free form of the lipoprotein of
Escherichia coli
. However, the peak was not observed in
Proteus mirabilis
. The protein at the peak in
S. typhimurium
was shown to contain little or no histidine as expected from the amino acid composition of the lipoprotein. Furthermore, antiserum against the highly purified lipoprotein from
E. coli
was shown to react with the proteins from
S. typhimurium
and
S. marcescens
and to form the specific immunoprecipitates. In contrast, the protein from
P. aeruginosa
did not react with the antiserum at all. Thus, it is concluded that
S. typhimurium
and
S. marcescens
have the free form of the lipoprotein in their envelopes as does
E. coli. P. aeruginosa
contains a protein of the same size as the lipoprotein, but it is not certain whether the protein is the same structural protein as the lipoprotein from
E. coli. P. mirabilis
may not have any free form of the lipoprotein, may have it in a very small amount, or may have a lipoprotein of different molecular weight serving the same function.
Natural Messenger Ribonucleic Acid-Directed Cell-Free Protein-Synthesizing System of
Bacillus subtilis
Authors: Legault-Demare Lucienne , Chambliss Glenn H.
Published: January 2020

A very active in vitro protein-synthesizing system has been developed from
Bacillus subtilis
. High activity in the extracts is dependent upon precautions taken to reduce proteolytic activity. Endogenous, exogenous natural and synthetic messenger ribonucleic acids (RNAs) are translated by the system. The activity of the
B. subtilis
system has been compared to that of the
Escherichia coli
system. With either SPO1 RNA or polyuridylic acid, the activities of the two systems were very similar. Electrophoresis of the products synthesized in vitro by the two systems primed with SPO1 RNA yields similar radioactive profiles. The major bands of radioactivity correspond to proteins of molecular weight between 15,000 and 40,000.
Requirement of Deoxyribonucleic Acid Synthesis for Microcycle Sporulation in
Bacillus megaterium
Authors: Mychajlonka Myron , Slepecky Ralph A.
Published: January 2020

Bacillus megaterium
cells have been examined during outgrowth for their macromolecular content, ability to undergo microcycle sporulation, the time of their growth division, the time of deoxyribonucleic acid (DNA) replication initiation, and their ability to synthesize DNA after transfer to sporulation medium. The increase in total DNA content of the cells increased discontinuously beginning at 90 min. Thymidine incorporation became insensitive to chloramphenicol between 90 and 105 min of outgrowth. At 90 min the cells acquired the ability to undergo microcycle sporulation and the degree of sporulation depended on the time spent in outgrowth, with maximal sporulation occurring at 180 min. During outgrowth, cells underwent one synchronous growth division beginning at 225 min and ending at 270 min. Outgrowing cells were not able to continue DNA synthesis after transfer to sporulation medium. The data suggest that DNA replication starts before cells are able to undergo microcycle sporulation; however, the initiation of replication may not be the only requirement for microcycle sporulation.
Methionine-Dependent Synthesis of Ribosomal Ribonucleic Acid During Sporulation and Vegetative Growth of
Saccharomyces cerevisiae
Authors: Wejksnora Peter J. , Haber James E.
Published: January 2020

Methionine limitation during growth and sporulation of a methionine-requiring diploid of
Saccharomyces cerevisiae
causes two significant changes in the normal synthesis of ribonucleic acid (RNA). First, whereas 18
S
ribosomal RNA is produced, there is no significant accumulation of either 26
S
ribosomal RNA or 5.8
S
RNA. The effect of methionine on the accumulation of these RNA species occurs after the formation of a common 35
S
precursor molecule which is still observed in the absence of methionine. During sporulation, diploid strains of
S. cerevisiae
produce a stable, virtually unmethylated 20
S
RNA which has previously been shown to be largely homologous to methylated 18
S
ribosomal RNA. The appearance of this species is not affected by the presence or absence of methionine from sporulation medium. However, when exponentially growing vegetative cells are starved for methionine, unmethylated 20
S
RNA is found. The 20
S
RNA, which had previously been observed only in cells undergoing sporulation, accumulates at the same time as a methylated 18
S
RNA. These effects on ribosomal RNA synthesis are specific for methionine limitation, and are not observed if protein synthesis is inhibited by cycloheximide or if cells are starved for a carbon source or for another amino acid. The phenomena are not marker specific as analogous results have been obtained for both a methionine-requiring diploid homozygous for
met13
and a diploid homozygous for
met2
. The results demonstrate that methylation of ribosomal RNA or other methionine-dependent events plays a critical role in the recognition and processing of ribosomal precursor RNA to the final mature species.
Morphogenesis and Ultrastructure of
Claviceps purpurea
During Submerged Alkaloid Formation
Authors: Voříšek J. , Ludvík J. , Řeháček Z.
Published: January 2020

Criteria for morphogenetic and ultrastructural distinction between conidia and chlamydospores of a submerged culture of
Claviceps purpurea
(Fr.) Tul. are described. Both the hyphae of the sphacelia (asexual) stage and the conidia contained granular cytoplasm. Cytoplasmic invaginations in vacuoles were transformed to electron-opaque bodies and disintegrated prior to germination. The budding of conidia had basipetal succession. The chlamydospores were formed by rounding up the terminal cells of filamentous hyphae. Homogeneous nonvacuolized cytoplasm with lipid droplets and lipid-forming bodies was characteristic of young chlamydospores. Cristate mitochondria did not appear in the chlamydospores before the alkaloid production phase. Simultaneously a specific organelle in the chlamydospores, a dense body, appeared to absorb intracellular lipids and form large deposits of phospholipid material. No germination of chlamydospores was observed. The ultrastructural pattern described for chlamydospores was also observed in hyphae with reduced proliferation during the alkaloid production phase.
Detection of nonintegrated plasmid deoxyribonucleic acid in the folded chromosome of Escherichia coli: physiochemical approach to studying the unit of segregation
Authors: Kline B C , Miller J R
Published: January 2020

Physiocochemical evidence presented indicates plasmid deoxyribonucleic acid (DNA) can associate with host chromosome without linear insertion of the former into the latter. This conclusion is based on the observation that covalently closed circular (CCC) plasmid DNA can cosediment with undegraded host chromosome in a neutral sucrose gradient. When F plus bacteria are lysed under conditions that preserve chromosome, approximately 90% of CCC F sex factor plasmid (about 1% of the total DNA) is found in folded chromosomes sedimenting at rates between 1,500 and 4,000s. The remaining 10% of the CCC F DNA sediments at the rate (80S) indicative of the free CCC plasmid form. Reconstruction experiments in which 80S, CCC F DNA is added to F plus or F minus bacteria before cell lysis show that exogenous F DNA does not associate with folded chromosomes. In F plus bacteria, F plasmid is harbored at a level of one or two copies per chromosomal equivalent. In bacteria producing colicin E1, the genetic determinant of this colicin, the Col E1 plasmid, is harbored at levels of 10 to 13 copies per chromosomal equivalent; yet, greater than 90% of these plasmids do not cosediment with the 1,800S species of folded chromosome. However, preliminary evidence suggests one or two Col E1 plasmids may associate with the 1,800S folded chromosome. Based on evidence presented in this and other papers, we postulate F plasmid can link to folded chromosome because the physicochemical structure of the plasmid resembles a supercoiled region of the chromosome and, therefore, is able to interact with the ribonucleic acid that stabilizes the folded chromosome structure. Implications of this model for F plasmid replication and segregation are discussed.
Lipid metabolism during bacterial growth, sporulation, and germination: kinetics of fatty acid and macromolecular synthesis during spore germination and outgrowth of Bacillus thuringiensis
Authors: Nickerson K W , De Pinto J , Bulla L A
Published: January 2020

The timing and kinetics of fatty acid synthesis are delineated for Bacillus thuringiensis spore germination and outgrowth by analyzing [U-14C]acetate and [2-3H]glycerol incorporation into chloroform-methanol-extractable and trichloroacetic acid-precipitable lipids. In addition to measurement of pulsed and continuous labeling of fatty acids, monitoring the incorporation of radioactive phenylalanine, thymidine, and uridine from the onset of germination through first cell division provides a profile of biochemical activities related to membrane differentiation and cellular development. Upon germination, ribonucleic acid synthesis is initiated, immediately followed by rapid and extensive fatty acid synthesis that in turn precedes protein, deoxyribonucleic acid and triglyceride synthesis. Significantly, formation of fatty acids from acetate exhibits further developmental periodicity in which a large transient increase in fatty acid synthetic activity coincides with the approach of cell division. Radiorespirometric analyses indicates only slight oxidative decarboxylation of acetate and corroborates the extreme involvement of acetate in specific fatty acid biosynthetic reactions throughout cellular modification. These findings graphically demonstrate an intimate association of fatty acid metabolism with commitment to spore outgrowth and subsequent cell division.
Comparative analysis of the lipids of Acinetobacter species grown on hexadecane
Authors: Makula R A , Lockwood P J , Finnerty W R
Published: January 2020

A comparative analysis of the cellular and extracellular lipids of Acinetobacter species HO1-N indicated basic physiological differences in hexadecane-grown cells. The cellular lipids obtained from hexadecane-grown cells were characterized by 3- and 18-fold increases in the phospholipid fraction and the mono- and diglyceride fraction, respectively, over that obtained from nutrient broth-yeast extract-grown cells. The cellular-associated pools of hexadecane were shown to comprise approximately 8% of the dry cell weight of hexadecane-grown cells. The extracellular lipids obtained from the culture broths of hexadecane-grown cells were comprised of triglyceride, mono- and diglyceride, free fatty acid, and wax ester. These lipids were either absent or present in minor concentrations in the culture broths of nutrient broth-yeast extract-grown cells. The exponential growth of Acinetobacter sp. on hexadecane was characterized by the significant accumulation of free fatty acid, monoglyceride, and diglyceride in the culture medium. Wax ester was shown to represent a minor portion of the extracellular lipids during the exponential growth phase, appearing in significant proportion only after the culture had entered the stationary phase of growth.
Regulation of arylsulfatase synthesis by sulfur compounds in Klebsiella aerogenes
Authors: Adachi T , Murooka Y , Harada T
Published: January 2020

In Klebsiella aerogenes, arylsulfatase synthesis was repressed by inorganic sulfate, sulfite, sulfide, thiosulfate, and cysteine, but not by methionine under normal growth conditions. We isolated cysteine-requiring mutants (Cys minus), and mutants (AtsS minus, AtsR minus) in which the regulation of arylsulfatase synthesis was altered. In the cysteine auxotroph, enzyme synthesis was also repressed by inorganic sulfate or cysteine. Kinetic studies on mutants of the cysteine auxotroph showed that inorganic sulfate repressed arylsulfatase synthesis and that this was not due to cysteine formed by reduction of sulfate. Arylsulfatase synthesis in the AtsS minus mutant was not repressed by inorganic sulfate but was repressed by cysteine. This mutant strain had a normal level of inorganic sulfate transport. Another mutant strain, defective in the inorganic sulfate transport system, synthesized arylsulfatase in the presence of inorganic sulfate but not in the presence of cysteine. The AtsS minus mutant could synthesize the enzyme in the presence of inorganic sulfate but not cysteine. The AtsR minus mutant could synthesize the enzyme in the presence of either inorganic sulfate or cysteine. These results suggest that there are two independent functional corepressors of arylsulfatase synthesis in K. aerogenes.
Genetic control of glutamine synthetase in Klebiella aerogenes
Authors: Streicher S L , Bender R A , Magasanik B
Published: January 2020

Mutations at two sites, glnA and glnB, of the Klebsiella aerogenes chromosome result in the loss of glutamine synthetase. The locations of these sites on the chromosome were established by complementation by episomes of Escherichia coli and by determination of their linkage to other genetic sites by transduction with phage P1. The glnB gene is located at a position corresponding to 48 min on the Taylor map of the E. coli chromosome; it is linked to tryA, nadB, and GUA. The glnA gene is at a position corresponding to 77 min on the Taylor map and is linked to rha and metB; it is also closely linked to rbs, located in E. coli at 74 min, indicating a difference in this chromosomal region between E. coli and K. aerogenes. Mutations in the glnA site can also lead to nonrepressible synthesis of active glutamine synthetase. The examination of the fine genetic structure of glnA revealed that one such mutation is located between two mutations leading to the loss of enzymatic activity. This result, together with evidence that the structural gene for glutamine synthetase is at glnA, suggests that glutamine synthetase controls expression of its own structural gene by repression.
Protoplast formation and leakage of intramembrane cell components: induction by the competence activator substance of pneumococci
Authors: Seto H , Tomasz A
Published: January 2020

Treatment of pneumococci with activator (a protein that induces bacterial "competence" to absorb deoxyribonucleic acid molecules and undergo genetic transformation) can cause either protoplast formation or leakage of intracellular components to the medium depending on postincubation conditions. The leaked intracellular components include nucleoside phosphates, beta-galactosidase, deoxyribonuclease, autolysin, and hemolysin. Leakage and protoplast formation are induced by the electrophoretically pure activator, and these phenomena require the same conditions as induction of competence for genetic transformation, namely, genetic capacity for competence, protein synthesis, incorporation of choline, and the optimal pH for activation. It is suggested that the activator protein accelerates a normal process of transport (leakage) of autolysin molecules into the periplasmic space. The activity of these autolysin molecules from within would then unmask deoxyribonucleic acid binding sites located on the plasma membrane.
Rejoining of radiation-induced single-strand breaks in deoxyribonucleic acid of Escherichia coli: effect of phenethyl alcohol
Authors: Nair C K , Pradhan D S , Sreenivasan A
Published: January 2020

Single-strand breaks in deoxyribonucleic acid of Escherichia coli B/r cells exposed to 20 krads of gamma radiation could be rejoined by incubation of irradiated cells in growth medium. In the presence of 0.25% phenethyl alcohol, this repair was completely inhibited although deoxyribonucleic acid and protein syntheses were suppressed only partially.
Isolation of covalently closed circular deoxyribonucleic acid from Streptomyces coelicolor A3(2)
Authors: Schrempf H , Bujard H , Hopwood D A , Goebel W
Published: January 2020

Covalently closed circular deoxyribonucleic acid (DNA) was isolated from two strains of Streptomyces coelicolor A3(2), representing two of the known fertility types. In each of the two strains circular DNA of about 20 times 10-6 daltons could be detected, amounting to about 1.5% of the total cellular DNA. The possible function of this DNA is discussed.
Assay of deoxyribonucleic acid homology using a single-strand-specific nuclease at 75 C
Authors: Barth P T , Grinter N J
Published: January 2020

We investigated the conditions under which a crude preparation of endonuclease S1 gives maximal hydrolysis of denatured deoxyribonucleic acid (DNA) while giving minimal hydrolysis of native DNA. The hydrolysis was measured by filtering and determining the acid-insoluble reaction product using 3H-labeled substrates. We also investigated various parameters in making this measurement. Under appropriate conditions (in 1 mM ZnSO-4, 0.168 M NaCl at pH 4.8) denatured DNA is hydrolyzed within 3% of completion whereas native DNA is essentially unaffected. The reaction was applied to assay plasmid DNA homoand heteroduplexes for which the method proves to be simple, fast, and reproducible.
Genetic analysis of thymidine-resistant and low-thymine-requiring mutants of Escherichia coli K-12 induced by bacteriophage Mu-1
Authors: Buxton R S
Published: January 2020

Four genes, dra, tpp, drm, and pup, that specify enzymes involved in the catabolism of nucleosides and deoxynucleosides in Escherichia coli are known to be very closely linked in the order dra-tpp-drm-pup. By infecting cells with the phage Mu-1 and isolating low-thymine-requiring derivatives of a strain lacking thymidylate synthetase and also thymidine-resistant mutants of a dra-strain, it has been possible to select for strains in which Mu-1 is inserted in this gene cluster. Making use of the polar effect of Mu-induced mutations on more distal genes in the same transcriptional unit, evidence is presented that dra and tpp are co-transcribed from a promoter to the left of dra, and drm and pup are co-transcribed from a promotor located between tpp and drm. Residual levels of purine nucleoside phosphorylase in drm- mutants induced by phage Mu seem to indicate that a weak promotor lies between drm and pup. From a strain in which Mu-1 is inserted in drm, a mutant has been isolated that has a deletion extending into tpp. Since this strain lacks thymidylate synthetase, it is unable to grow on minimal medium containing thymine. Mutants isolated from this strain that can grow on minimal medium containing thymine have been shown to have increased levels of the enzyme uridine phosphorylase.
Polarized relationship of bacterial spore loci to the "old" and "new" ends of sporangia
Authors: Hitchins A D
Published: January 2020

The frequency of association of spore loci with the "old" and "new" ends of rod-shaped sporangia in batch cultures of Bacillus megaterium ATCC 19213 was estimated by phase contrast microscopy. The analysis was facilitated by (i) the association of most of the sporangia into chains of two to five sporangia and (ii) the occurrence of two types of cross wall distinguishable by their degree of splitting. It was concluded that a newly formed spore is located at the "old" end of a sporangium. By inference, the sporulation division septum locus is distal to the ultimate normal cell division septum, i.e., proximal to the "old" pole of the B. megaterium sporangium. This result is discussed in relation to deoxyribonucleic acid segregation during sporulation.
Genes affecting the productivity of alpha-amylase in Bacillus subtilis Marburg
Authors: Sekiguchi J , Takada N , Okada H
Published: January 2020

Genetic control of alpha-amylase (alpha-1,4-glucan glucanohydrolase, EC 3.2.1.1.) production by Bacillus subtilis 168 was studied from the standpoint that alpha-amylase production by bacteria is dependent on a long-lived messenger ribonucleic acid and obeys the following equation: E = kappa integral of X-DT where x = cell mass at time t, E = alpha amylase produced, t = culture time, and kappa = productivity constant. So a productivity constand (kappa) is obtained from the slope of the straight line plot of alpha-amylase formed versus the total mass of cells accumulated over that time during the culture process. The following results were obtained. (i) Two sequential mutants, derived from the 168(kappa = 20) strain and having improved alpha-amylase productivity (168 leads to 196), were analyzed for their serine and metal protease production. Strain 128 (kappa = 40) produced half the amount of both proteases, but strain 196 (kappa = 60 similar to 80) produced 20 times that in the original strain. (ii) Amy+ transformants, using the 196 strain as the other three had higher productivity (kappa = 37 similar to 46). These transformants (J71, J47, groups. Seventy-one of 74 Amy+ transformants had a kappa value of 21.0 plus or minus 2.1 and the other three had higher productivity (kappa = 37 similar to 46). These transformants (J71,J47, and J10) produced levels of serine and metal proteases 20 times higher than the other transformants. (iii) Strains 196, J71, J47, and J10 were found to be nonmotile and resistant to phage PBS1, whereas other strains, including strains 168, 128, 3 revertants of strain J71 and 2 revertants of strain 196, were all motile and sensitive to the phage. (iv) Strains 196 and J71 were nonflagellated under electron microscopic observation but strain 168, 128 and a revertant of J71 were flagellated. From the above experimental results, the existence of a quality controlling gene (amyB) was deduced, which is loosely linked to the structural gene and controls productivities of alpha-amylase and proteases, and flagellation. The probable existence of another regulatory gene, amyC, is also discussed.
Nucleotide pools and regulation of ribonucleic acid synthesis in yeast
Authors: Kudrna R , Edlin G
Published: January 2020

Nucleotide pools were measured in growing and amino acid-starved Saccharomyces cerevisiae. During amino acid starvation there are neither significant changes in the endogeneous nucleoside triphosphate pool levels nor measurable synthesis of guanosine 5'-diphosphate, 3'-diphosphate. Stable ribonucleic acid synthesis does not appear to be regulated by changes in the triphosphate pools or by the unusual nucleotide guanosine 5'-diphosphate, 3'-diphosphate.
Positive control in the D-serine deaminase system of Escherichia coli K-12
Authors: Bloom F R , McFall E , Young M C , Carothers A M
Published: January 2020

Two new types of D-serine deaminase (Dsdase)-negative mutants have been isolated and characterized. The first fails to synthesize a functional dsdC gene product as a result of dsdC- (regulator negative) mutations. The mutations lie in the dsdC region, are cis and trans recessive to dsdC+, and give rise to revertants of novel regulatory phenotype. The second class consists of Dsdase-negative lysogens in which the phenotype is the result of the integration of lambdac1857 Sam7 into the dsdC region. Lambda lysates derived from two of the Dsdase-negative lysogens can transduce the structural gene for Dsdase (dsdA) but not the dsdC region. The dsdC+ gene product had no repressor effect on constitutive synthesis in a strain containing a dsdO (initiator constitutive) and a dsdC- mutation. These and other findings indicate that control of Dsdase synthesis is strictly positive. The partial trans effect of the dsdC+ gene product on constitutive synthesis in dsdCc (regulator constitutive) strains can thus be explained by "subunit mixing" between active dsdCc subunits and dsdC+ subunits which are inactive in the absence of the inducer, D-serine. The order of genes in the dsd region is supN-dsdC-dsdP-dsdA-aroC.
Effect of tsl mutations in decreasing radiation sensitivity of a recA- strain of Escherichia coli K-12
Authors: Mount D W , Walker A C , Kosel C
Published: January 2020

It has been shown previously that the radiation sensitivity of lexA- strains of Escherichia coli K-12 can be suppressed by thermosensitive mutations (designated tsl) that are closely linked to the lexA locus and are thought to be intragenic suppressors of lexA mutations (Mount et al., 1973). When a recA mutation is crossed into a suppressed tsl- strain, the extreme radiation sensitivity usually conferred by a recA mutation is decreased, but there is no detectable change in genetic recombination deficiency. Increased resistance to UV in the tsl-reA-strains depends upon ability to synthesize active uvrA+ product.
Procedure for Isolating Mutants Defective in Metabolite Transport or Utilization
Authors: Berg Claire M. , Rossi John J. , Coleman Joyce V. , Conlon Michele
Published: January 2020

Mutants defective in uptake or utilization of a given metabolite can readily be obtained from facultative auxotrophs (for that metabolite) by penicillin enrichment under nonpermissive conditions in the presence of a low level of the required metabolite.
Regulation of branched-chain aminoacyl-transfer ribonucleic acid synthetases in an ilvDAC deletion strain of Escherichia coli K-12
Authors: Coleman W , Kline E L , Brown C S , Williams L S
Published: January 2020

Valyl-, isoleucyl-, and leucyl-transfer ribonucleic acid synthetase formation was compared in isogenic strains of Escherichia coli K-12 that differed only in that one strain carried a deletion of three genes of the ilv gene cluster, ilvD, -A, and -C. It was found that: (i) the activities of these synthetases in the deletion strain were less than those in the normal strain during growth in minimal medium supplemented with excess isoleucine, valine, and leucine, and (ii) their stability was reduced in the deletion strain during specific branched-chain amino acid limitations. The results of density-labeling experiments suggest that the in vivo stability of valyl-, isoleucyl-, and leucyl-transfer ribonucleic acid synthetases requires some product missing in the ilvDAC deletion strain.
Regulation of ribosomal protein synthesis in Escherichia coli B/r
Authors: Dennis P P , Young R F
Published: January 2020

The differential synthesis rate of ribosomal protein (r-protein), alpha-r (synthesis rate of r-protein divided by synthesis rate of total protein), was measured during the cell division cycle. It was observed that alpha-r remained essentially constant and was not measurably affected by duplication of the r-protein gene cluster (i.e., str-spc region) during the process of chromosome replication. It was further observed that the rate of total protein synthesis and r-protein synthesis increased continuously and uniformly during the entire cell cycle. This gene dosage independence of the synthesis rate of r-protein was similar to that observed earlier for the synthesis of ribosomal ribonucleic acid (rRNA). These observations indicate that the synthesis rates of the protein and RNA components of the ribosome are coordinately balanced during the entire cell division cycle and are not significantly perturbed by duplication of the r-protein or rRNA genes. Furthermore, this balanced synthesis insures that neither free rRNA nor free r-protein accumulate in appreciable amounts during balanced growth.
Effect of aeration on minimal medium recovery of heated Salmonella typhimurium
Authors: Gomez R F , Sinskey A J
Published: January 2020

The effect of presence or absence of air on minimal medium recovery of heated Salmonella typhimurium was investigated. It was determined that the expression of minimal medium recovery is not only dependent on heat and a nutritionally complex medium but also on air. Unlike in the presence of air, in the presence of nitrogen, cells were able to recover their ability to grow on Trypticase soy agar enriched with 0.5% yeast extract (TSY) when incubated in TSY broth. It was established that in the presence of nitrogen the number of heat-TSY- induced, single-straneded breaks in deoxyribonucleic acid (DNA) were less than in the presence of air. Furthermore, the DNA breaks in nitrogen were repaired, whereas DNA breaks in air were not. The ability of cells to grow on TSY agar corresponded well with their ability to repair damage to DNA.
Determination of the active portion of the folic acid molecule in cellular slime mold chemotaxis
Authors: Pan P , Hall E M , Bonner J T
Published: January 2020

From earlier work it is known that folic acid attracts the amoebae of various species of cellular slime molds (11). Here we have tested a wide variety of pteridines, pyrimidines, and pyrazines to determine what part of the folic acid molecule is chemotactically active. It was shown that the activity lies in the pteridine ring itself. Furthermore, the cell-free supernatants of slime mold amoebae contain an enzyme that renders pterin and folic acid chemotactically inactive, which apparently increases the chemotactic sensitivity of the amoebae to those compounds. Despite the fact that slime mold amoebae secrete small amounts of folic acid-related compounds, there is no evidence that folates are acrasins; rather it is postulated that attraction to folates may be a food-seeking device for the amoebae which prey on folate-secreting bacteria in the soil.
Electron microscopy studies of the limiting layers of the rickettsia Coxiella burneti
Authors: Burton P R , Stueckemann J , Paretsky D
Published: January 2020

Surface layers of Coxiella burneti studied at a high resoulution reveal a plasma membrane and an outer surface membrane 6 to 7 nm thick, and a thin, moderately electron-dense intermediate layer associated with the inner surface of the outer membrane of many cells. This layer appears to be unaffected by lysozyme treatment. Ruthenium red staining was used to delineate a layer of filamentous material external to the outer membrane; this fuzzy layer has a mean thickness of 20 nm and is not often seen on the surface of cells prepared by conventional means. Both antigenic phase I and II cells show a ruthenium red-binding surface layer. It is suggested that this fuzzy layer may be, among other possibilities, a highly branched mucopolysaccharide.
Deletion of the
Escherichia coli crp
Gene
Authors: Sabourin Dennis , Beckwith Jon
Published: January 2020

Spontaneous
crp
mutants
Escherichia coli
were selected from a strain that does not require 3′,5′-cyclic adenosine monophosphate for CAP activity. Several deletions of the
crp
gene were characterized. The
crp
gene was not essential for growth of
E. coli. crp
mutations reduced the donor ability of Hfr strains.
Demonstration That Thymine Dimers are Excised as Oligonucleotides from Specifically Incised Ultraviolet-Irradiated Deoxyribonucleic Acid
Authors: Pawl Gary , Slor Hanoch , Friedberg Errol C.
Published: January 2020

The average size of the dimer-containing acid-soluble oligonucleotides after incubation of specifically incised DNA with two dimer excising nuclease activities has been determined to be about 8 nucleotides.