bluuebunny/crossref_metadata_2025 huggingface dataset:
Neurospora crassa cytoplasmic ribosomes: cold-sensitive mutant defective in ribosomal ribonucleic acid synthesis
Authors: Russell P J , Hammett J R , Selker E U
Published: January 2020

Experiments were conducted to characterize further the biochemical defects of crib-1 (PJ30201), a coldsensitive mutant strain of Neurospora crassa with a defect in ribosome biosynthesis. The results are as follows. (i) The critical temperature for the expression of the mutant growth and ribosome phenotypes is in the range of 18 to 20 C. (ii) No preferential breakdown of 37S cytoplasmic ribosomal subunits synthesized by crib-1 at 25 C occurs after a shift to 10 C. (iii) Ribosomal subunits synthesized by crib-1 at 25 C function normally in in vivo protein synthesis at 10 C. (iv) Whereas wild type synthesizes both ribosomal subunits in a coordinate manner after either a temperature shift-down (25 to 10 C) of a shift-up (10 to 25 C), noncoordinate synthesis of ribosomal subunits owing to underproduction of 37S subunits occurs in the crib-1 strain immediately after a temperature shift-down. (v) After a shift from 10 to 25 C crib-1 exhibits a 12-h lag before the growth rate and the rate of synthesis of 37S subunits begin to increase significantly. (vi) At 10 C crib-1 synthesizes unequal amounts of 25S and 17S ribosomal ribonucleic acid (rRNA) molecules, resulting from a greatly reduced accumulation of stable 17S rRNA. The mutant phenotypes of crib-1 are proposed to be the result of a defect in rRNA processing.
Suppressor mutations in Pseudomonas aeruginosa
Authors: Watson J M , Holloway B W
Published: January 2020

Suppressor mutations of Pseudomonas aeruginosa have been identified. An isolate of strain PAT, initially selected as being temperature sensitive for growth, was found to suppress two different auxotrophic mutations. A suppressor locus, designated sup-1, has been mapped and is co-transducible with three closely linked thr loci. The suppressor mutation has been used to isolate suppressor-sensitive (sus) mutants of the virulent phage E79 and the R factor R18. By selecting for revertants of auxotrophic markers, other sup mutants have been isolated and are found to be of two types, either temperature sensitive for growth like the original mutant or showing wild-type growth at 43 C. The mutations giving rise to both these classes of suppressor are very closely linked. One of the sup-1 alleles of strain PAT also shows suppressor activity when transferred into P. aeruginosa strain PAO. Escherichia coli strains carrying the nonsense suppressors supC, supD, or supF do not suppress the sus mutant of R18. This suggests that sup-1 is different from the amber and ochre suppressors of the enterobacteria.
Hfr formation by I pilus-determining plasmids in Escherichia coli K-12
Authors: Datta N , Barth P T
Published: January 2020

R483, an atypical, I pilus-determining plasmid, and also R144, a typical one, were shown to suppress the DnaA phenotype by integration into the Escherichia coli chromosome.
Ubiquity of plasmids in coding for toluene and xylene metabolism in soil bacteria: evidence for the existence of new TOL plasmids
Authors: Williams P A , Worsey M J
Published: January 2020

Thirteen bacteria have been isolated from nine different soil samples by selective enrichment culture on m-toluate (m-methylbenzoate) minimal medium. Eight of these were classified as Pseudomonas putida, one as a fluorescent Pseudomonas sp., and four as nonfluorescent Pseudomonas sp. All 13 strains appeared to carry TOL plasmids superficially similar to that previously described in P. putida mt-2 in that: (i) all the wild-type strains could utilize toluene, m-xylene, and p-xylene as sole carbon and energy sources, (ii) these growth substrates were metabolized through the corresponding alcohols and aldehydes to benzoate, m-toluate, and p-toluate, respectively, and thence by the divergent meta (or alpha-ketoacid) pathway, and (iii) the isolates could simultaneously and spontaneously lose their ability to utilize the hydrocarbons, alcohols, aldehydes, and acids, particularly during growth on benzoate, giving rise to cured strains which could grow only on benzaldehyde and benzoate of the aromatic substrates by the alternative ortho (or beta-ketoadipate) pathway. Eight of the isolates were able to transfer their TOL plasmids into their own cured strains, but only five were able to transfer them in interstrain conjugation into the cured strains, but only five were able to transfer them in interstrain conjugation into the cured derivative of P. putida mt-2. However, P. putida mt-2 was able to transfer its TOL plasmid into 11 of the cured isolates, and eight of these were able to retransmit this foreign plasmid in intrastrain conjugation with their own cured derivatives. Three of the isolates, MT 14, MT 15, and MT 20, differed significantly from the others in that the wild-type strains dissimilated the p-methyl-substituted substrates poorly, and also, during growth on benzoate, in addition to the cured derivatives, they gave rise to derivatives with a phenotype intermediate between the cured and wild-type strains, the biochemical and genetic nature of which has not been elucidated.
Thermal denaturation of mesophilic and thermophilic 5S ribonucleic acids
Authors: Varricchio F , Marotta C A
Published: January 2020

The Tm of Bacillus stearothermophilus 5S ribonucleic acid (RNA) is 1.5 +/- 0.5 C higher than that of 5S RNAs from B. subtilis and Escherichia coli. Melting in 50% methanol and in formaldehyde indicate that both base stacking and helical regions are involved in the slightly increased thermal stability of B. stearothermophilus 5S RNA. It is probable that the 5S RNA makes only a minor contribution to the thermostability of B. stearothermophilus 50S ribosomal subunits.
Regulation of lysine transport by feedback inhibition in Saccharomyces cerevisiae
Authors: Morrison C E , Lichstein H C
Published: January 2020

A steady-state level of about 240 nmol/mg (dry wt) occurs during lysine transport in Saccharomyces cerevisiae. No subsequent efflux of the accumulated amino acid was detected. Two transport systems mediate lysine transport, a high-affinity, lysine-specific system and an arginine-lysine system for which lysine exhibits a lower affinity. Preloading with lysine, arginine, glutamic acid, or aspartic acid inhibited lysine transport activity; preloading with glutamine, glycine, methionine, phenylalanine, or valine had little effect; however, preloading with histidine stimulated lysine transport activity. These preloading effects correlated with fluctuations in the intracellular lysine and/or arginine pool: lysine transport activity was inhibited when increases in the lysine and/or arginine pool occurred and was stimulated when decreases in the lysine and/or arginine pool occurred. After addition of lysine to a growing culture, lysine transport activity was inhibited more than threefold in one-third of the doubling time of the culture. These results indicate that the lysine-specific and arginine-lysine transport systems are regulated by feedback inhibition that may be mediated by intracellular lysine and arginine.
Escherichia coli mutants altered in murein lipoprotein
Authors: Wu H C , Lin J J
Published: January 2020

Mutants with alterations in the structure, biosynthesis, or assembly of murein lipoprotein were selected by a procedure based on radiation suicide of wild-type organisms by [3H]arginine under conditions where the radioactive arginine was preferentially incorporated into lipoprotein. Further screening for the potential mutants among the survivors of [3H]arginine suicide was carried out by using a sensitive immunodiffusion test, followed by radioactive double-labeling experiments. Three mutants were obtained and partially characterized.
Regulation of purine utilization in bacteria. VI. Characterization of hypoxanthine and guanine uptake into isolated membrane vesicles from Salmonella typhimurium
Authors: Jackman L E , Hochstadt J
Published: January 2020

Uptake of hypoxanthine and guanine into isolated membrane vesicles of Salmonella typhimurium TR119 was stimulated by 5'-phosphoribosyl-1'-pyrophosphate (PRPP). For strain proAB47, a mutant that lacks guanine phosphoribosyltransferase, PRPP stimulated uptake of hypoxanthine into membrane vesicles. No PRPP-stimulated uptake of guanine was observed. For strain TR119, guanosine 5'-monophosphate and inosine 5'-monophosphate accumulated intravesicularly when guanine and hypoxanthine, respectively, were used with PRPP as transport substrates. For strain proAB47, IMP accumulated intravesicularly with hypoxanthine and PRPP as transport substrates. For strain TR119, hypoxanthine also accumulated when PRPP was absent. This free hypoxanthine uptake was completely inhibited by N-ethylmaleimide, but the PRPP-stimulated uptake of hypoxanthine was inhibited only 20% by N-ethylmaleimide. Hypoxanthine and guanine phosphoribosyltransferase activity paralleled uptake activity in both strains. But, when proAB47 vesicles were sonically treated to release the enzymes, a three- to sixfold activation of phosphoribosyltransferase molecules occurred. Since proAB47 vessicles lack the guanine phsophoribosyltransferase gene product and since hypoxanthine effectively competes out the phosphoribosylation of guanine by proAB47 vesicles, it was postulated that the hypoxanthine phosphoribosyltransferase gains specificity for both guanine and hypoxanthine when released from the membrane. A group translocation as the major mechanism for the uptake of guanine and hypoxanthine was proposed.
Lysine catabolism in Rhizoctonia leguminicola and related fungi
Authors: Guengerich F P , Broquist H P
Published: January 2020

The catabolism of lysine was studied in several yeasts and fungi. Results with cell-free extracts of Rhizoctonia leguminicola support a proposed pathway involving (D- and L-) EPSILON-N-acetyllysine, alpha-keto-epsilon-acetamidohexanoic acid, delta-acetamidovaleric acid, and delta-aminovaleric acid in the conversion of L-lysine to shortchain organic acids. Label from radioactive L-lysine was found to accumulate in D- and L-epsilon-N-acetyllysine, delta-acetamidovaleric acid, delta-aminovaleric acid, and glutaric acid in cultures of R. leguminicola, Neurospora crassa, Saccharomyces cerevisiae, and Hansenula saturnus, suggesting that the proposed omega-acetyl pathway of lysine catabolism is generalized among yeasts and fungi. In N. crassa, as is the case in R. leguminicola, the major precursor of L-pipecolic acid was the L-isomer of lysine; 15N experiments were consistent with delta1-piperideine-2-carboxylic acid as an intermediate in the transformation.
Dual regulation by arginine of the expression of the Escherichia coli argECBH operon
Authors: Kryzek R A , Rogers P
Published: January 2020

The correlation between the level of messenger ribonucleic acid (mRNA) specific for the argECBH gene cluster (argECBH mRNA) measured by ribonucleic acid-deoxyribonucleic acid (RNA-DNA) hybridization and the rates of synthesis of N-acetylornithine deacetylase (argE enzyme) and of argininosuccinate lyase (argH enzyme) of Escherichia coli strain K-12 were determined for steady-state growth with and without added L-arginine and during the transition periods between these two states. During the transient period after arginine removal (transient derepression), the synthesis of enzymes argE and argH was initially three to five times greater than the steady-state derepressed rate finally reached 50 min later. The level of argECHB mRNA correlated well both quantitatively and temporally with the rates of enzyme synthesis during this transition. The level of in vivo charged arginyl-transfer RNA (tRNAarg), monitored simultaneously, was initially only 5 to 10% and gradually increased to a final level of 80% after 45 min. During the transient period after arginine addition (transient repression), the rates of synthesis of enzymes argE and argH decreased to almost zero and gradually reached steady-state repressed rates after about 180 min. The argECBH mRNA level remained constant at the steady-state repressed level throughout transient repression, revealing a discontinuity between the level of this mRNA and rates of enzyme synthesis. A similar discrepancy was noted during the transition after ornithine addition. In vivo charged tRNAarg remained constant at 80% during this transition. After removal of arginine, the zero-level transient enzyme synthesis developed after only 7.5 min of arginine deprivation and was maximum after 30 min. The results suggest an accumulation of a molecule regulated by arginine that plays a role in transient repression. Our data indicate that arginyl-tRNA synthetase is not this molecule since its synthesis was unaffected by arginine. The ratios of steady-state argE and argH enzyme synthesis without arginine to that with arginine were 12 and 20, respectively, whereas the similar ratio for argECBH mRNA was 2 to 3. The repressed level of argECBH mRNA was not affected by attempts to repress or derepress the ppc+ gene (carried on the DNA used for hybridization), and the repressed level of argECBH mRNA was lowered about 50% in cells carrying an internal argBH deletion. These data taken together indicate the presence of an excess of untranslated argECBH mRNA during both transient and steady-state repression by arginine. Thus, a second regulatory mechanism, not yet defined, appears to play an important role in arginine regulation of enzyme synthesis.
Isolation of plasmid deoxyribonucleic acid from Pseudomonas putida
Authors: Palchaudhuri S , Chakrabarty A
Published: January 2020

Conditions suitable for reproducible recovery of covalently closed circular deoxyribonucleic acid from strains of Pseudomonas putida containing degradative plasmids (CAM, SAL, OCT, etc.) have been defined. These degradative plasmids could not be isolated by the usual procedure, whereas RP1, an R factor of the P group, present in the isogenic strain of P. putida, was isolated equally well by either the usual procedure or the modified procedure. Characterization by electron microscopy of RP1 deoxyribonucleic acid confirmed the molecular weight (about 40 X 10(6)) previously determined by sucrose gradient centrifugation.
Mode of insertion of lipopolysaccharide into the outer membrane of escherichia coli
Authors: Kulpa C F , Leive L
Published: January 2020

A mutant of Escherichia coli that lacks uridine 5'-diphosphate galactose-4-epimerase makes lipopolysaccharide with less carbohydrate than the parent, unless galactose is present during growth. Carbohydrate is dense, and the outer membrane, which contains lipopolysaccharide, was found to be denser when isolated from cells grown with galactose then when galactose was omitted. Cells given galactose after growth in its absence rapidly formed dense regions within the outer membrane that disappeared when galactose was removed. These results indicate that lipopolysaccharide enters the outer membrane nonrandomly at a minimum of 10 to 22 discrete "insertion points." Isopycnic centrifugation provides a method for isolating these regions.
Isolation and Genetic Analysis of Amber
uvrA
and
uvrB
Mutants
Authors: Morimyo Mitsuoki , Shimazu Yoshie , Ishii Naoaki
Published: January 2020

Genetic properties of amber
uvrA
and
uvrB
mutants of
Escherichia coli
K-12 are described. The isolation of three amber
uvrA
and two amber
uvrB
mutants indicates that the products of these genes are proteins.
Cyanide-Resistant Respiration of a
Neurospora crassa
Membrane Mutant
Authors: Juretic Davor
Published: January 2020

Choline starvation of the
Neurospora crassa chol-1
mutant leads to a decrease in respiration through the cytochrome chain and a concomitant induction of the alternate oxidase.
Evidence For Autogenous Regulation of
Pseudomonas putida
Tryptophan Synthase
Authors: Proctor Alan R. , Crawford Irving P.
Published: January 2020

Studies of a
trpA
mutant constitutive for tryptophan synthase production support the hypothesis of autogenous regulation (R. F. Goldberger, 1974; A. R. Proctor and I. P. Crawford, 1975) of the
Pseudomonas putida trpAB
loci.
cheA, cheB, and cheC genes of Escherichia coli and their role in chemotaxis
Authors: Parkinson J S
Published: January 2020

Motile but generally nonchemotatic (che) mutants of Escherichia coli were isolated by a simple screening method. A total of 172 independent mutants were examined, and four genes were defined on the basis of mapping and complemenvestigated by determining their null phenotypes with nonsense or bacteriophage Mu-induced mutations. The cheA and cheB products were essential in producing changes of swimming direction and flagellar rotation. The checC product appeared to be an essential component of the flagellum; however, specific mutational alterations of this component allowed flagellar assembly but prevented directional changes in swimming. Since some cheB mutants changed directions incessantly, this gene product may also serve to control the direction of flagellar rotation in response to chemoreceptor signals. Thus most or all of the common elements in the signalling process were involved in the generation and regulation of changes in the direction of flagellar rotation.
Mechanisms of siderophore iron transport in enteric bacteria
Authors: Leong J , Neilands J B
Published: January 2020

Uptake of 55Fe- and 3H-labeled siderophores and their chronic analogues have been studied in Salmonella typhimurium LT-2 and Escherichia coli K-12. In S. typhimurium LT-2, at least two different mechanisms for siderophore iron transport may be operative. Uptake of 55Fe- and 3H-labeled ferrichrome and kinetically inert lambda-cis-chromic [3H]deferriferrichrome by the S. typhimurium LT-2 enb7 mutant, which is defective in the production of its native siderophore, enterobactin, appears to occur by two concurrent mechanisms. The first mechanism is postulated to involve either rapid uptake of iron released from the ferric complex by cellular reduction without penetration of the complex or ligand or dissociation of the complex and simultaneous uptake of both ligand and iron coupled with simultaneous expulsion of the ligand. The second mechanism appears to consist of slower uptake of the intact ferric complex.
Relationship between hemagglutinin and sialidase from Clostridium perfringens CN3870: chromatographic characterization of the biologically active proteins
Authors: Rood J I , Wilkinson R G
Published: January 2020

Biochemical characterization of hemagglutinin and sialidase activities from Clostridium perfringens strain CN3870 revealed that this strain produced three sialidase enzymes that were separable to gel filtration, ion exchange chromatography, and polyacrylamide gel electrophoresis. The molecular weights of sialidase I, II, and III activities were 310,000 +/- 10,000, 105,000 +/- 4,000 and 64,000 +/- 2,000, respectively, the first figure being an approximate value only.
Ultrastructure of developing ascospores in Sordaria brevicollis
Authors: Hackett C J , Chen K C
Published: January 2020

The ultrastructure of ascospore wall formation in the pyrenomycete Sordaria brevicollis was studied in developing asci at progressive time intervals. From early spore delimitation through final stage of maturation, the wall of the ascospore differentiated into four composite layers, the periascosporium the delineation ascosporium, the subascosproium, and the endoascosproium, While ascospores were at the hyaline stage of development,they possessed only the periascosporium and delineation ascosporium as their wall components. At about 7 to 8 days from the initiation of the cross, the spores developed a yellow color, and this coloration was always associated with the elaboration of the subascorsporium just internal to the ascosporium. Asthe spores continued to progressively darken in color, the subascosporium was seen to increase in complexity, electron density, and thickness. Soon after the formation of the subascosporium, the endoascosporium began to develop de novo and was, therefore, the last wall layer formed as the spore approached maturity.
Centrifugal separation of irradiated cultures of Escherichia coli cells into viable and nonviable populations
Authors: Schenley R L , Fisher W D , Swenson P A , Khachatourians G G
Published: January 2020

Incubation of ultraviolet-irradiated Escherichia coli B/r cultures with 0.7% Triton X-100 resulted in a large decrease in turbidity. Under phase-contrast optics, most of the irradiated detergent-treated cells were smaller than normal and of low phase density; only a small percentage were normal or larger than normal and of normal phase density. Irradiated cells not treated with detergent showed fewer pronounced morphological changes. Irradiated cells treated with detergent lost large amounts of proteins and ribonucleic acid, but not of deoxyribonucleic acid. Such cultures could be separated by centrifugation into populations of (i) slowly sedimenting cells consisting of small, phase-light cells of low viability and (ii) large cells of normal phase density and high viability (100%). A similar separation was effected in gamma-irradiated cultures.
Altered deoxyribonucleotide pools in P2 eductants of Escherichia coli K-12 due to deletion of the dcd gene
Authors: Neuhard J , Thomassen E
Published: January 2020

Deletion of the Escherichia coli K-12 chromosome associated with P2 mediated education extend through the structural gene for uridine kinase, udk, and the dcd gene encoding 2'-deoxycytidine 5'-triphosphate deaminase. The lack of uridine kinase makes a positive selection possible for these strains. Due to the dcd mutation, P2 eductants show large alterations in their deoxyribonucleoside triphosphate pools.
Variation in levels of enzymes related to energy metabolism in alternative developmental pathways of Blastocladiella emersonii
Authors: Ingebretsen O C , Sanner T
Published: January 2020

The activities of phosphofructokinase (PFK), fructose diphosphatase (FDP), nicotinamide adenine dinucleotide (NAD) and NAD phosphate (NADP)-linked isocitrate dehydrogenases (IDHNAD, IDHNADP), two NAD-linked glutamate dehydrogenases (GDH1, GDH2), and isocitrate lyase were studied during the development of the two phenotypes, ordinary colorless and resistant sporangia (OC and RS plants), of water mold Blastocladiella emersonii in synchronized liquid cultures. The OC plants had a generation time of about 12 h, whereas the RS plants required 3.5 days to reach maturity. All the enzymes were present throughout the development of both phenotypes. In zoospores, PFK, FDP, and GDH2 were localized in the cytosol. The IDHNADP activity was distributed with two-thirds in the soluble and one-third in the particulate fraction. GDH1 and IDHNAD showed the same distribution and were predominantly present in the particulate fraction, presumably in the mitochondria. Isocitrate lyase was found in the particulate fraction. The enzyme levels changed considerably during development. FDP and IDHNADP varied in a parallel manner. Similarly, the three enzymes PFK, IDHNAD and GDH1 showed parallel variations. The activity patterns for all enzymes were different for the OC and RS pathways. Isocitrate lyase exhibited the largest changes in activity during development. Thus, during OC plant formation, its activity decreased by a factor of 20. GDH2 varied similarly to PFK and IDHNADP during OC plant development, whereas it behaved like isocitrate lyase during RS plant development. The ratios between anabolic and catabolic enzymes were higher in mature plants than in zoospores and higher in RS plants than in OC plants. The results indicate that the variations in the enzyme levels are secondary to the critical changes involved in the transition from one developmental pathway to the other.
Inheritance of nocardiophage phi EC in matings of nocardial lysogens
Authors: Brownell G H , Adams J N
Published: January 2020

Lysogens of Nocardia erythropolis were mated with nonlysogenic strains to study the inheritance of the phi EC prophage. Crosses between lysogenic strains of the Mat-Ce mating type and nonlysogenic Mat-cE strains produced Mat-cE lysogens at a recovery rate of 17%, whereas recombination frequencies between chromosomal traits were about 2.3 x 10(-5). Crosses of lysogenic Mat-cE mating types with nonlysogenic Mat-Ce produced Mat-Ce lysogens at a recovery rate of 19%, whereas recombinants for chromosomal traits were recovered at only 1.8 x 10(-5). Crosses of homologous mating types, lysogenic Mat-Ce with nonlysogenic Mat-Ce or lysogenic Mat-cE with nonlysogenic Mat-cE, failed to transfer the prophage. It was concluded that the phi EC prophage exists as a plasmid and can be transferred at high frequencies with patterns of transfer controlled like typical nocardial fertility. Evidence that the prophage may also exist as an integrated element was observed from recombination analyses.
Disruption of the fucose pathway as a consequence of genetic adaptation to propanediol as a carbon source in Escherichia coli
Authors: Hacking A J , Lin E C
Published: January 2020

In Escherichia coli, L-fucose is dissimilated via an inducible pathway mediated by L-fucose permease, L-fucose isomerase, L-fucose kinase, and L-fuculose 1-phosphate aldolase. The last enzyme cleaves the six-carbon substrate into dihydroxyacetone phosphate and L-lactaldehyde. Aerobically, lactaldehyde is oxidized to L-lactate by a nicotinamide adenine dinucleotide (NAD)-linked dehydrogenase. Anaerobically, lactaldehyde is reduced by an NADH-COUPLED REDUCTASE TO L-1,2-propanediol, which is lost into the medium irretrievably, even when oxygen is subsequently introduced. Propanediol excretion is thus the end result of a dismutation that permits further anaerobic metabolism of dihydroxy-acetone phosphate. A mutant selected for its ability to grow aerobically on propanediol as a carbon and energy source was reported to produce lactaldehyde reductase constitutively and at high levels, even aerobically. Under the new situation, this enzyme serves as a propanediol dehydrogenase. It was also reported that the mutant had lost the ability to grow on fucose. In the present study, it is shown that in wild-type cells the full synthesis of lactaldehyde dehydrogenase requires the presence of both molecular oxygen and a small molecule effector, and the full synthesis of lactaldehyde reductase requires anaerobiosis and the presence of a small molecule effector. The failure of mutant cells to grow on fucose reflects the impairment of a regulatory element in the fucose system that prevents the induction of the permease, the isomerase, and the kinase. The aldolase, on the other hand, is constitutively synthesized. Three independent fucose-utilizing revertants of the mutant all produce the permease, the isomerase, the kinase, as well as the aldolase, constitutively. These strains grow less well than the parental mutant on propanediol.
Chemical composition and turnover of peptidoglycan in Neisseria gonorrhoeae
Authors: Hebeler B H , Young F E
Published: January 2020

The peptidoglycan of all four colonial types of a number of strains of Neisseria gonorrhoeae constituted 1 to 2% of the dry weight of the cell. The chemical composition of cell types examined was similar with molar ratios of 1:1:2:1:1 for muramic acid, glucosamine, alanine, glutamic acid, and diaminopimelic acid, respectively. Ninety-six percent of the mass of the peptidoglycan was composed of these compounds. A lipoprotein analogous to that observed in Escherichia coli was not detected. The chain length of the glycan varied from 80 to 110 disaccharide units. The peptide contained equimolar amounts of D- and L-alanine. The rate of turnover of peptidoglycan in strain RD5 was 50% per generation. Turnover proceeded without a lag and followed first-order kinetics.
Rapid Nuclear Staining Method forSaccharomyces cerevisiae
Authors: Slater Martin L.
Published: January 2020

Mithramycin was used to stain nuclei in mitotically dividing and sporulating yeast.
Regulation of enzyme formation in Klebsiella aerogenes by episomal glutamine synthetase of Escherichia coli
Authors: Streicher S L , Deleo A B , Magasanik B
Published: January 2020

We studied the physiology of cells of Klebsiella aerogenes containing the structural gene for glutamine synthetase (glnA) of Escherichia coli on an episome. The E. coli glutamine synthetase functioned in cells of K. aerogenes in a manner similar to that of the K. aerogenes enzyme: it allowed the level of histidase to increase and that of glutamate dehydrogenase to decrease during nitrogen-limited growth. The phenotype of mutations in the glnA site was restored to normal by the introduction of the episomal glnA+ gene. These results are consistent with the hypothesis that glutamine synthetase regulates the function of its own structural gene.
Isolation and genetic characterizaion of Escherichia coli K-12 mutations affecting bacteriophage T5 restriction by the ColIb plasmid
Authors: Hull R , Moody E E
Published: January 2020

A mutant derivative of Escherichia coli K-12 has been isolated which is permissive for bacteriophage T5 infection even when harboring a wild-type ColIb plasmid. The fully permissive phenotype was the result of two mutations that are located near the rpsL-rpsE region on the E. coli chromosome and are recessive to the wild-type alleles. These mutations had little or no effect on induction of colicin synthesis and did not affect the expression of antibiotic resistance by the resistance plasmids R64drd11 or R1drd19. Cells harboring the mutant alleles grew more slowly than isogenic wild-type derivatives in either minimal or complete media.
Wild-type and mutant in vitro products of an operon for ribonucleic acid polymerase subunits
Authors: Austin S
Published: January 2020

An in vitro protein-synthesizing system can synthesize two ribonucleic acid (RNA) polymerase subunits of Escherichia coli, beta and beta', when a transducing phage deoxyribonucleic acid (DNA) template containing the rpoB region of the bacterial chromosome is added. Recombinant rpoB transducing phages were isolated that carry "nonsense" mutations of the class rpo-rifampin zero amber (formally referred to as rifoam). DNA was extracted from two of these phages. These DNAs are unable to direct the synthesis of beta subunits, whereas beta' synthesis is unaffected. Both mutations can be efficiently suppressed in vitro by the addition of suppressor transfer RNA. One of the mutations (rpoB115) produces a detectable nonsense (or restart) fragment of the beta protein in the absence of suppression. It is concluded that rpoB115 is an amber mutation within the structural gene for the beta subunit of RNA polymerase.
Enhanced transformability with heterospecific deoxyribonucleic acid in a Streptococcus sanguis mutant impaired in ribonucleic acid polymerase activity
Authors: Raina J L , Ravin A W
Published: January 2020

We have induced with nitrosoguanidine in Streptococcus sanguis a mutation conferring inability to grow and synthesize ribonucleic acid (RNA) at 42 C, the optimal temperature for growth and RNA synthesis in the parental strain. The mutation (ts) is transferable via transforming deoxyribonucleic acid (DNA) and is replaceable by its wild-type allele with fairly high efficiency in transformation reactions. The ts mutation is unlinked to the sites of mutation conferring resistance of rifampin (rifr) and streptolydigin (stgr), known to affect the beta subunit of DNA-dependent RNA polymerase. Extracts from strains carrying the ts mutation are more sensitive to elevated temperatures than are parental extracts when assayed for DNA-dependent RNA polymerase. The conclusion that the mutation causes a temperature-sensitive defect in some component of this enzyme (other than beta) is supported by the finding that the polymerase activity of a heat-inactivated ts stgr extract cannot be increased by addition of an unheated ts stgs extract, which is itself inactivated by streptolydigin. S. sanguis recipients carrying the ts mutation are highly transformable with heterospecific DNA, especially at the restrictive temperature.
Regulation of beta-glucuronidase synthesis in Escherichia coli K-12: constitutive mutants specifically derepressed for uidA expression
Authors: Novel M , Novel G
Published: January 2020

All methyl-beta-D-galacturonide-positive mutants isolated from Escherichia coli K-12 carry constitutive mutations for beta-glucuronidase (UID) synthesis. Most of these mutants are specific for UID synthesis and are distributed in three classes according to the derepression level of UID. Each specific mutant carries a mutation(s) near uidA, the structural gene for UID, at min 30.5 of the E. coli K-12 linkage map. The expression of UID synthesis in F-merodiploid strains carrying these mutations permits discrimination between dominant and recessive constitutivity over the wild-type allele. The first kind of mutation (dominant) should affect the operator site uidO of the structural gene uidA; the second type of mutation (recessive) should affect a regulatory gene, uidR, operating through a negative control. The isolation of mutants bearing at this locus superrepressed mutations, which can revert to produce a constitutive phenotype, confirms the occurrence of such a regulatory gene. The partially derepressed uidR mutants of the first class are normally inducible and remain constitutive at low temperature; their UID has the same thermal sensitivity as in the wild-type strains. The occurrence of similar regulatory gene mutants has been recently described in the lactose system (Shineberg, 1974).
Mutants of Salmonella typhimurium deficient in an endoprotease
Authors: Miller C G , Heiman C , Yen C
Published: January 2020

Three bands of hydrolytic activity toward the chromogenic protease substrate N-acetyl-DL-phenylalanine beta-naphthyl ester (NAPNE) can be observed after gel electrophoresis of crude extracts of Salmonella typhimurium or Escherichia coli. Mutants deficient in one of these three activities have been isolated using a staining procedure that identifies colonies that show reduced ability to hydrolyze NAPNE. These mutants lack the strongest of the three bands of activity. The Salmonella mutations (designated apeA) are all co-transducible with purE, and the order (pro)-apeA-Hfr K17 origin-purE has been established. Strains carrying apeA mutations have wild-type doubling times. None of the apeA mutants isolated gains an auxotrophic requirement as a result of loss of the apeA gene product. The rates and extents of protein degradation during starvation for a carbon source or during growth after exposure to the amino acid analogue canavanine do not seem to be affected by apeA mutations. Revertants of apeA mutations (selected by screening for clones that have regained the ability to hydrolyze NAPNE) frequently contain a new enzymatic activity not found in wild-type cells.
Inactivation of the Phosphoenolpyruvate-Dependent Phosphotransferase System in Various Species of Bacteria by Vinylglycolic Acid
Authors: Snyder Mark A. , Kaczorowski Gregory J. , Barnes Eugene M. , Walsh Christopher
Published: January 2020

The alkenoic hydroxyacid 2-hydroxy-3-butenoic acid (vinylglycolate) specifically inhibited the phosphotransferase system in a variety of bacteria while not affecting respiration-coupled transport systems.
Natural and altered induction of the L-fucose catabolic enzymes in Klebsiella aerogenes
Authors: Saint Martin E J , Mortlock R P
Published: January 2020

Mutants of Klebsiella aerogenes W70 were isolated that had gained the ability to utilize the uncommon pentose D-arabinose as their sole source of carbon and energy. In contrast to the D-arabinose-negative, parent strain, these mutants were found to be either constitutive for certain enzymes of the L-fucose catabolic pathway or inducible for such enzymes when incubated in the presence of D-arabinose. The mutants used L-fucose isomerase to convert D-arabinose to D-ribulose, which is an intermediate and inducer of the ribitol catabolic pathway. The D-ribulokinase of the ribitol pathway was then induced. This enzyme catalyzed the phosphorylation of D-ribulose at the 5-carbon position. Mutants that were negative for D-ribulokinase could still dissimilate D-arabinose slowly by using all three enzymes, the isomerase, kinase, and aldolase, of the L-fucose pathway. Using condition negative mutants, we were able to demonstrate that the natural induction of the L-fucose pathway enzymes by L-fucose required the activity of a functional L-fucose isomerase and a functional L-fuculokinase but not an L-fuculose-1-phosphate aldolase. A metabolic intermediate, L-fuculose-1-phosphate, was thereby shown to be a probable inducer of at least the isomerase and kinase of the L-fucose catabolic pathway. Similar experiments, with D-arabinose-positive mutants, which were induced for the L-fucose pathway enzymes upon incubation with D-arabinose, revealed that the activities of the L-fucose isomerase and the L-fuculokinase were also required for the induction of the L-fucose enzymes. These D-arabinose-positive mutants apparently produced an altered regulatory protein that accepted both L-fuculose-1-phosphate and D-ribulose-1-phosphate as inducers. Examination of constitutive mutants revealed that L-fucose isomerase and L-fuculokinase were both synthesized constitutively, with the aldolase apparently under separate control.
Escape Synthesis of
d
-Serine Deaminase in λ
dsdC
Integration Lysogens
Authors: Carothers Adelaide M. , McFall Elizabeth
Published: January 2020

Heat shock of lysogens that contain λ thermosensitive repressor mutants integrated into the
dsdC
gene results in escape synthesis of
d
-serine deaminase at a high differential rate.
Deoxyribonucleic acid-binding studies on the hut repressor and mutant forms of the hut repressor of Salmonella typhimurium
Authors: Hagen D C , Magasanik B
Published: January 2020

In Salmonella typhimurium the genes coding for the enzymes of histidine utilization (hut) are clustered in two adjacent operons, hutMIGC and hut(P,R,Q)UH. A single repressor, the product of the C gene, regulates both operons by binding at two operator sites, one near M and one in (P,R,Q). The deoxyribonucleic acid (DNA)-binding activity of the repressor was measured using DNA's containing separate operators. The repressor had greater activity when assayed using DNA containing the operator of the (P,R,Q)UH operon than when assayed using DNA containing the operator of the MIGC operon. The binding to either operator was absent in the presence of the inducer, urocanate. The DNA-binding activities were also determined for two super-repressors. The super-repressors had altered DNA-binding properties, although the self-regulated nature of the repressors complicated the analysis of the results. A purfication procedure for the wild-type repressor is presented. The purified repressor was somewhat unstable, and additional experiments using it were not performed.
Membrane lipoteichoic acid of Streptococcus pyogenes and its stabilized L-form and the effect of two antibiotics upon its cellular content
Authors: Slabyj B M , Panos C
Published: January 2020

Membrane lipoteichoic acid continues to be synthesized by an osmotically fragile, stabilized L-form of Streptococcus pyogenes. Chromatographic and electrophoretic comparisons indicate that the lipid componenent of lipoteichoic acid in this L-form and its parental streptococcus is glycerophosphoryldiglucosyl diglyceride and not phosphatidylkojibiosyl diglyceride. Based upon dry weight determinations, the yield of lipoteichoic acid from the L-form is 0.19%, as compared with 0.97% from the streptococcus. When grown with bacitracin the L-form contains the same amount of teichoic acid as when grown without this antibiotic; however, its lipoteichoic acid content is reduced by 85%. Similarly, the L-form grown with novobiocin for 10 h contains only 17% of the teichoic acid found in control cells.
Envelope-associated folded chromosomes for Escherichia coli: variations under different physiological conditions
Authors: Korch C , Ovrebo S , Kleppe K
Published: January 2020

The folded chromosome of Escherichia coli has been investigated under various lysis and physiological conditions. A new gradient system was devised that allows excellent separation between unlysed cells and envelope-associated and envelope-free chromosomes. Isotope incorporation experiments showed that the fraction often called "membrane-bound nucleoids" contains cell wall in addition to nucleic acids, membranes, and proteins. The amount of lysozyme added and the lysozyme digestion time were found to be important when comparing the rate of sedimentation of envelope-associated chromosomes obtained under various physiological conditions. Amino acid-starved cells were found to be much harder to lyse with lysozyme than exponentially grown cells, The difference in sedimentation coefficient of envelope-associated chromosomes described earlier (Ryder and Smith, 1974) was not detected when the latter two types of cells had been given equivalent, but not identical, lysozyme treatment such that detergent-mediated lysis proceeded at the same rate. Analysis of pulse- and uniformly labeled chromosomes from amino acid-starved cultures revealed no preferential labeling of either envelope-associated or -released nucleoids. Nor was there a difference in sedimentation coefficient between uniform and pulse-labeled envelope-associated nucleoids. These results are in disagreement with the models for chromosome replication of Worcel and Burgi (1974) and Ryder and Smith (1974), respectively. Growing cells on carbon sources poorer than glucose demonstrated that the replicating chromosomes sediment faster than the bulk of envelope-associated nucleoids. The slower the growth rate, the greater this difference became. An alternative hypothesis regarding chromosome replication and its association with the cell envelope is presented.
Catechol oxygenases of Pseudomonas putida mutant strains
Authors: Bayly R C , McKenzie D I
Published: January 2020

Investigation of a mutant strain of Pseudomonas putida NCIB 10015, strain PsU-E1, showed that it had lost the ability to produce catechol 1,2-oxygenase after growth with catechol. Additional mutants of both wild-type and mutant strains PsU-E1 have been isolated that grow on catechol, but not on benzoate, yet still form a catechol 1,2-oxygenase when exposed to benzoate. These findings indicate that either there are separately induced catechol 1,2-oxygenase enzymes, or that there are two separate inducers for the one catechol 1,2-oxygenase enzyme. Comparisons of the physical properties of the catechol 1,2-oxygenases formed in response to the two different inducers show no significant differences, so it is more probable that the two proteins are the product of the same gene. Sufficient enzymes of the ortho-fission pathway are induced in the wild-type strain by the initial substrate benzoate (or an early intermediate) to commit that substrate to metabolism by ortho fission exclusively. A mechanism exists that permits metabolism of catechol by meta fission if the ortho-fission enzymes are unable to prevent its intracellular accumulation.
Enterobacterial common antigen in rfb deletion mutants of Salmonella typhimurium
Authors: Mäkelä P H , Schmidt G , Mayer H , Nikaido H , Whang H Y , Neter E
Published: January 2020

The his-rfb deletion series of Salmonella typhimurium mutants characterized previously by Nikaido et al. was examined for the presence of the enterobacterial common antigen (ECA). All deletions not extending further to the left than the genes for cytidine phosphoabequose synthesis were ECA positive, whereas longer deletions (extending to the genes for thymidine diphosphorhamnose synthesis or further) were ECA negative. When these long-his-rfb deletion strains were studied further, it became clear that they (four out of four studied) had accumulated a second mutation, called rff, close to ilv, which prevented the synthesis of ECA. When rff- was replaced by rff+, the recombinants, now having the his-rfb deletion only, produced traces of ECA, showed reduced viability, increased sensitivity to sodium dodecyl sulfate (SDS) and to a lesser extent, to other anionic detergents, and accumulated secondary "suppressor" mutations upon storage. Such suppressor-containing mutants could be isolated by selecting for resistance to 1% SDS. Thirty of 46 SDS-resistant mutants studied had a second mutation, which alone prevented the synthesis of ECA, close to ilv. This ilv-linked mutation was similar to the rff mutation of the strains studied originally. The new rff mutation was similar to previously described rfe mutations in its close linkage to ilv and association with an ECA-negative phenotype. It differed from rfe, however, by not affecting the synthesis of the O antigens (O-6,7) of group C1. In Salmonella group C1, all ECA genes identified thus far are linked to ilv (rfe and/or rff) and none is linked to rfb.
Mapping of a new genetic locus responsible for ampicillin resistance in Escherichia coli
Authors: Buchanan C E , Strominger J L
Published: January 2020

The ampicillin resistance locus of three different ampicillin-resistant, temperature-sensitive Escherichia coli mutants was mapped between proC and purE and does not correspond to any of the known genes in this region. The mutant gene responsible for the temperature sensitivity and consequent morphological changes in each mutant strain was not located in the same 5-min region, even though the two mutants characteristics co-reverted at a very high frequency.
Energy cost of galactoside transport to Escherichia coli
Authors: Purdy D R , Koch A L
Published: January 2020

Energy reserves of Escherichia coli can be depleted by our previously reported procedure to a level such that even the "downhill" transport of o-nitrophenyl-beta-D-galactopyranoside (ONPG) is completely dependent upon the exogenous energy supply. The ONPG concentration is high externally to the cells and is low intracellular because of the action of cytoplasmic beta-galactosidase. In the present work, depleted cell suspensions have been infused at low, steady rates with glucose and other energy sources while measurements of transport were being made. Comparing the rate of ONPG transport with the rate of introduction of glucose under conditions where the chosen glucose infusion rate limits transport, we find that 89 molecules of ONPG are transported per molecule of fully oxidized glucose. This transport yield is constant over a 6.5-fold range in rate of glucose addition. This constancy over a range of infusion rates implies that transport is the major cellular function under these special conditions. The yield value if 89 is in the agreement with the predicitions of 76 from Mitchell's chemiosmotic theory and constitutes an independent proff of its validity, since all the other proposed mechanisms of engery coupling predict much smaller yields. The lag from the start of glucose infusion into the reaction cuvette, to the extrapolated time at which a steady rate of transport and concomitant hydrolysis are achieved, is short (approximately 1 min). Similarly, the time after the infusion is stopped until the rate of transport returns to the background rate is also short. The latter implies that the energy metabolism is directed almost entirely to transport and/or other ongoing cellular processes and not to repair or renewal of an energy-independent, facilitated diffusion system.