bluuebunny/crossref_metadata_2025 huggingface dataset:
Specificity and genetics of S-adenosylmethionine transport in Saccharomyces cerevisiae
Authors: Petrotta-Simpson T F , Talmadge J E , Spence K D
Published: January 2020

The specificity of a transport system for S-adenosylmethionine was determined through the use of structurally related derivatives. Of the compounds tested, the analogues S-adenosylethionine and S-inosylmethionine and the naturally occurring compounds S-adenosyl-(5')-3-methylthiopropylamine and S-adenosylhomocysteine competitively inhibited uptake of the sulfonium compound. Ki values for these compounds indicate that the order of affinity for the transport protein is S-adenosylmethionine congruent to S-adenosyl-(5')-3-methyl-thiopropylamine greater than S-adenosylethionine greater than S-inosylmethionine greater than S-adenosylhomocysteins. S-adenosyl-(2-hydroxy-4-methylthio)butyric acid exerted inhibition of a mixed type. S-insoyl-(2-hydroxy-4-methylthio)butyric acid, S-inosylhomocysteine, and S-ribosylhomocysteine were without effect. On the basis of the inhibition data, the methionine-amino, adenine-amino, and methyl groups were identified as group important in the binding of S-adenosylmethionine to the transport protein. Comparison is made with the specificities of various transmethylating enzymes utilizing S-adenosylmethionine. In addition, a number of conventional and temperature-sensitive S-adenosylmethionine transport mutants were isolated and analyzed in an attempt to identify the structural character of the specific transport protein(s). The data obtained suggest that only a single gene (a single polypeptide) is involved in specific S-adenosylmethionine transport. Apparent interallelic complementation supports the assumption that the functional form of the protein is composed of two or more copies of a monomer.
Immunological study of anthranilate synthetase
Authors: Reiners J J , Zalkin H
Published: January 2020

An immunological study of anthranilate synthetase (ASase) has been initiated using quantitative precipitation, enzyme neutralization, and immunodiffusion methods. Cross-reactivity of anthranilate synthetase-anthranilate-5-phosphoribosylpyrophosphate phosphoribosyltransferase (ASase-PRTase) from Escherichia coli, Klebsiella aerogenes, and Salmonella typhimurium and ASase from Serratia marcescens and Pseudomonas putida was detected with antibodies to ?E. coli trypsin-treated ASase. Cross-reactivity of antigens was also obtained with S. marcescens anti-ASase. Indices of dissimilarity verified the overall structural similarity of ASase-PRTase from E. coli, K. aerogenes, and S. typhimurium and the divergence from S. marcescens ASase. Further divergence of these enzymes from ASase in B. subtilis and P. putida was apparent. Precipitation of ASase components I and II (ASase CoI and ASase CoII) was obtained using anti-ASase or antiserum fractionated to contain component-specific antibodies. Anti-ASase inhibited enzyme activity to binding to determinants on both subunits. Anti-ASase CoI inhibited the ammonia-dependent reaction and interfered with amide transfer from glutaminyl-ASase CoII. Anti-ASase CoII inhibited the glutamine reaction by blocking amide transfer. Enzyme neutralization experiments indicate more conservation of determinants at the active site region of ASase CoII compared to ASase CoI in the enterobacteria. A particulate form of ASase-PRTase in E. coli, K. aerogenes, and S. typhimurium could be distinguished by quantitative precipitation and immunodiffusion.
Induction of alkane hydroxylase proteins by unoxidized alkane in Pseudomonas putida
Authors: Benson S , Shapiro J
Published: January 2020

In vitro complementation assays have been used to demonstrate the induction of alkane hydroxylase proteins in mutants lacking the ability to convert n-alkanes to their primary alcohols. Purified heptane is an effective inducer in a mutant lacking detectable hydroxylase activity.
Carotenoid pigments of facultatively anaerobic spirochetes
Authors: Greenberg E P , Canale-Parola E
Published: January 2020

Carotenoid pigments were purified from a previously undescribed, red, halophilic spirochete (spirochete RS1), and from Spirochaeta aurantia strain J1. Both spirochetes are facultative anaerobes and produce pigments when growing aerobically. The major pigments of the two spirochetes were identified by means of chromatographic analysis, absorption spectroscopy, hydride reduction, acetylation and silylation experiments, and mass spectrometry. It was concluded that the major pigment from spirochete RS1 was 4-keto-1',2'-dihydro-1'-hydroxytorulene. This conclusion was further supported by infrared spectroscopy and additional analytical data. The evidence showed that the major pigment from S. aurantia was 1',2'-dihydro-1'-hydroxytorulene. Chromatographic and spectrophotometric evidence indicated that this pigment was also present, as a minor carotenoid component, in spirochete RS1. These pigments have been previously detected almost exclusively in gliding bacteria, such as species of Flexibacter, Stigmatella, and Myxococcus. The occurrence of 4-keto-1',2'-dihydro-1'-hydroxytorulene and 1',2'-dihydro-1'-hydroxytorulene in both spirochetes and gliding bacteria may have significance with respect to the evolutionary development of these organisms.
Control of chromosome replication in thymine-requiring strains of Bacillus subtilis 168
Authors: Gillin F D , Ganesan A T
Published: January 2020

Study of the replication pattern of a number of B. subtilis 168 strains under controlled physiological conditions revealed great interstrain variation in control of replication. Replication patterns were calculated from ratios of purA16/leu-8 and purA16/metB5 transformation frequency. The thymine-independent strains are under strict regulation with an average of one replication position per chromosome during log phase. After starvation for required amino acids or sporulation, the chromosome is in a completed state with no replication forks (class I). In contrast, several thymine-requiring strains (class III) have an average of three to four replication positions per chromosome during log phase (multiforked replication) of which one to two remain uncompleted after amino acid starvation or sporulation. The other thymine-requiring strains studied are intermediate (class II) in that they have an average of two replication positions per chromosome during log phase and one after amino acid starvation or sporulation. Pulse chase experiments indicate that the deoxyribonucleic acid which is close to the chromosomal origin on each branch of the multiforked chromosome is bound to a rapidly sedimenting cellular fraction, presumably membrane.
Role of pyrimidine dimer excision in loss of potential streptomycin resistance mutations of ultraviolet-irradiated Escherichia coli on phosphate-buffered agar
Authors: Sideropoulos A S , Greenberg J
Published: January 2020

The frequency of ultraviolet (UV)-induced mutations to streptomycin resistance dropped rapidly when starved Escherichia coli strains WP-2 B/r and B/r T- were incubated on phosphate-buffered agar (PBA), but was reduced only slightly in a WP-2 hcr- mutant. During postirradiation, incubation viability remained approximately constant. Cells given an optimal recovery treatment with photo-reactivating light showed no further recovery if subsequently incubated on PBA. At least 70% of the mutations induced to streptomycin resistance by UV could be repaired. The loss of potential streptomycin-resistant mutants was markedly reduced in strain B/r T- when 5 mug of acriflavin or 700 mug of caffeine per ml was added to PBA. The excision of UV-induced thymine-containing dimers from E. coli tb/r T- was investigated. Dimer excision progressed more slowly when the cells were incubated on PBA containing acriflavin or caffeine. There was no congruity between the kinetics of dimer excision and the kinetics of mutant loss. Our results indicate that removal of potential streptomycin-resistant mutants is considerably faster than the excision of pyrimidine dimers.
Two modes of excision repair in toluene-treated Escherichia coli
Authors: Sharon R , Miller C , Ben-Ishai R
Published: January 2020

In toluene-treated Escherichia coli incision breaks accumulate during post-irradiation incubation in the presence of adenosine 5'-triphosphate (ATP). It is shown that incised deoxyribonucleic acid (DNA) is converted to high-molecular-weight DNA during reincubation in the presence of the four deoxyribonucleoside triphosphates (dNTP's) and nicotinamide adenine dinucleotide (NAD). This restitution process is ATP independent and N-ethylmaleimide insensitive and takes place only in polA+ strains. It is defective in strains carrying a mutation in the 5' leads to 3' exonucleolytic activity associated with DNA polymerase I. Repair of accumulated incision breaks differs from repair in which all the steps of the excision repair process occur simultaneously or in rapid succession. The latter is observed if toluene-treated E. coli are incubated immediately after irradiation in the presence of the four dNTP's, NAD, and ATP. It is shown that under these conditions dimer excision occurs to a larger extent than during repair of accumulated incision breaks and that, except in strains defective in polynucleotide ligase, incision breaks do not accumulate. This consecutive mode of repair is detectable in polA+ strains and at low doses also in polA mutants.
Proteinase C (carboxypeptidase Y) mutant of yeast
Authors: Wolf D H , Fink G R
Published: January 2020

A mutant of yeast lacking proteinase C (carboxypeptidase Y) activity has been found by using a histochemical stain to screen mutagenized colonies. This defect segregates 2:2 in meiotic tetrads. Cell extracts lacked the esterolytic, amidase, and proteolytic activities associated with proteinase C. The absence of proteinase C does not affect mitotic growth and has no obvious effect on the formation of viable ascospores or meiotic segregation. The mutant grows on peptides known to be cleaved by proteinase C in vitro. This finding is consistent with the idea that other enzymes exist in vivo with overlapping substrate specificities.
N-terminal amino acid sequences of D-serine deaminases of wild-type and operator-constitutive strains of Escherichia coli K-12
Authors: Heincz M C , McFall E
Published: January 2020

The N-terminal amino acid sequences of the D-serine deaminases from strains of Escherichia coli K-12 that harbor wild-type and high-level constitutive catabolite-insensitive operator-initiator regions are identical: Met-Ser-GluNH2-Ser-Gly-Arg-His-Cys. This result indicates that the operator-initiator region is probably distinct from the D-serine deaminase structural gene.
Tryptophan biosynthesis in Salmonella typhimurium: location in trpB of a genetic difference between strains LT2 and LT7
Authors: Stuttard C
Published: January 2020

Salmonella typhimurium prototrophs carrying a trpR mutation synthesize tryptophan biosynthetic enzymes constitutively. When feedback inhibition of anthranilate synthetase but not 5'-phosphoribosylpyrophosphate phosphoribosyltransferase activity was by-passed by growing cells on media supplemented with anthranilic acid, all trpR prototrophs overproduced and excreted tryptophan. However, the rate of tryptophan production depended on both the ancestry of the trpR strain and the integrity of its trpA gene. Prototrophs with trp genes derived from S. typhimurium strain LT2 produced tryptophan more efficiently than those with trp genes derived from strain LT7. This strain difference was cryptic insofar as it did not affect the growth rate; it was revealed only as a rate-limiting step in the constitutive biosynthesis of tryptophan in the presence of anthranilic acid, and was due to a lesion in the LT7-derived trpB gene. Strains with LT7-derived trp genes bearing a deletion in trpA produced tryptophan as readily as LT2 trpR prototrophs. This indicated that LT7-specific 5-phosphoribosylpyrophosphate phosphoribosyltransferase must be aggregated with the trpA gene produce to give an observable reduction of constitutive tryptophan production. The discovery of this strain difference has particular implications for studies involving the activities of trpA and B genes and their products in S. typhimurium and may have general significance for other studies involving different strains of Salmonella.
Mechanism of gap-filling during postreplication repair of ultraviolet damage in Haemophilus influenzae
Authors: Small G D
Published: January 2020

Deoxyribonucleic acid (DNA), pulse labeled after ultraviolet irradiation of excision-defective mutants of Haemophilus influenzae, is of lower single strand molecular weight than that of unirradiated cells but approaches the size of DNA from unirradiated cells upon further incubation in growth medium. This gap-filling process is controlled by the rec-1 gene. Gap-filling occurs normally in a temperature-sensitive DNA synthesis mutant at the restrictive temperature showing that normal semiconservative DNA synthesis is not necessary for gap-filling. To test for recombinational events after irradiation, the DNA synthesized after irradiation was radioactively labeled for a short time in medium containing 5-bromodeoxyuridine followed by incubation for various times in non-radioactive, 5-bromodeoxyuridine-containing medium. The DNA was denatured and analyzed isopycnically. The labeled DNA was initially "heavy," but later shifted toward lighter densities. This shift occurred in the temperature-sensitive DNA synthesis mutant at the restrictive temperature and in the recombination-defective mutant rec-2, but was not seen in the rec-1 mutant. The density shift can be interpreted as evidence that rather extensive exchanges occurred between parental DNA and the DNA made after irradiation. These results suggest that such exchanges are important for gap-filling in H. influenzae.
"Killer" character does not influence the transmission of mitochondrial genes in Saccharomyces cerevisiae
Authors: Young R A , Perlman P S
Published: January 2020

Three cytoplasmic genetic elements have been shown to be separate from mitochondrial deoxyribonucleic acid (DNA), [rho], in Saccharomyces cerevisiae: the killer character [k], omicron-DNA, and psi [psi]. Griffiths has suggested genetic interactions between [VENR] and [TETR] mutants possibly located on omicron-DNA and mitochondrial genetic markers, but possible interactions between the best characterized of the three, the killer character, and mitochondrial DNA have not been investigated. To test this we isolated cycloheximide-induced nonkiller segregants (NKS) of killer cells with suitable genetic markers and mated them in [k] x [k], [k] x [k], and (NKS) x (NKS) combinations. No differences in quantitative mitochondrial marker transmission between these groups were found in crosses illustrating the mitochondrial phenomena of bias, polarity, and suppressiveness. Our studies show that no intercellular interactions between [k] and (NKS) cells influence mitochondrial transmission genetics. Intracellular interactions between the smaller double-stranded ribonucleic acid of [k] and mitochondrial DNA also were not detected.
Methionine transport in Yersinia pestis
Authors: Montie D B , Montie T C
Published: January 2020

Yersinia pestis TJW, an avirulent wild-type strain, requires phenylalanine and methionine for growth. It was of interest to examine and define the methionine transport system because of this requirement. The methionine system showed saturation kinetics with a Km for transport of approximately 9 times 10(-7) M. After 8 s of methionine transport, essentially all of the methionine label appeared in S-adenosyl-L-methionine (SAM) as detected in ethanol extracts. Small amounts of free methionine was detected intracellularly after 1 min of transport. Addition of glucose increased significantly the amount of intracellular methionine at 1 min. A series of SAM metabolic products was detected after 90 s to 5 min of transport including: 5'-thiomethyladenosine, homoserine lactone, S-adenosyl homoserine, and a fluorescent methyl receptor compound. Results from assays for SAM synthetase in spheroplast fractions showed a small (16%) but significant portion of synthetase associated with the membrane. However, most of the enzyme activity was associated with the cytoplasmic fraction. Methionine transport was characterized by a high degree of stereospecificity. No competition occurred from structurally unrelated amino acids. Although uptake was inhibited by uncoupling and sulfhydryl reagents, no efflux was observed. Results using energy inhibitors on unstarved and starved cells showed that respiratory inhibitors such as potassium cyanide (KCN) and amytal were most effective, and that arsenate was least effective. KCN plus arsenate completely blocked utilization of energy derived from glucose, and KCN completely blocked utilization of energy deived from D-lactate. The data indicate that methionine transport in Y. pestis is linked to the trapping of methionine in SAM. The results further suggest that this transport system can be classified as a permease-bound system where transport is coupled to an energized membrane state and to respiration.
Synthesis of peptidoglycan in the form of soluble glycan chains by growing protoplasts (autoplasts) of Streptococcus faecalis
Authors: Rosenthal R S , Shockman G D
Published: January 2020

Protoplasts (autoplasts) of Streptococcus faecalis were produced by the action of native autolytic N-acetylmuramidase in the absence of added peptidoglycan hydrolases and were grown in osmotically stabilized medium containing L-[3H]lysine and D-[14C]alanine. To reduce the level of muralytic hydrolysis of glycan chains during growth, heat-inactivated cell walls were added to the medium to bind autolytic enzyme, and tetracycline (1 mug/ml) was added to inhibit further enzyme synthesis. Under these conditions, protoplasts synthesized newly labeled peptidoglycan in the form of soluble, infrequently peptide cross-linked glycan chains which were released into the supernatant medium. These relatively large glycan chains were not transferred to exogenously added cell walls.
Lag in adaptation to lactose as a probe to the timing of permease incorporation into the cell membrane
Authors: Koch A L
Published: January 2020

If bacteria are incapable of forming and incorporating proteins into the cytoplasmic membranes in all phases of the cell cycle, then not all cells from an asynchronous culture should be capable of growth when switched to a new carbon and energy source whose metabolism requires new membrane function. The transfer of an inducible culture to low lactose provides such a situation since the cells cannot grow unless galactoside permease can function to concentrate the lactose internally. From such experiments, it was concluded that the Y gene product of the lac operon is synthesized, incorporated, and can start functioning in active transport, at any time throughout the bulk of the cell cycle. Not only were the lags before growth re-ensued much shorter than would be expected if the membrane transport capability could only be developed in a small portion of the cycle, but brief pulses of a gratuitous inducer shortened the lags much further. Three types of Escherichia coli ML 30 culture were studied: cells that had exhausted the limiting glucose; cells taken directly from glucose-limited chemostats; and a washed suspension of highly catabolite repressed cells from cultures grown in high levels of glucose and gluconate. The growth studies reported here were performed on-line with a minicomputer. They represent at least an order of magnitude increase in accuracy in estimating growth parameters over previous instrumentation.
Role of Bacterial Ribosome Subunits in Barotolerance
Authors: Smith W. , Pope D. , Landau J. V.
Published: January 2020

The barotolerant nature of protein synthesis in
Pseudomonas fluorescens
is shown to be associated with the 30
S
ribosomal subunit.
Characterization of V-Prime Factors in
Escherichia coli
K-12
Authors: Kahn Phyllis L. , Clement Marilyn
Published: January 2020

An episome derived from an Hfr
v
(Hfr isolated from a V colicinogenic parent) strain of
Escherichia coli
K-12 was isolated and characterized. The direction of gene transfer was inverted from that in the original parental strain.
Protease associated with spores of Bacillus cereus
Authors: Tesone C , Torriani A
Published: January 2020

A proteolytic activity is associated with the dormant spores of Bacillus cereus T and can be solubilized by washing the spores with 1 M KCl. This proteolytic activity is responsible for the attack of beta chains of ribonucleic acid-polymerase in extracts of dormant spores of this organism.
Induction of alpha-glucosidase and synthesis during the cell cycle of Myxobacter AL-1
Authors: Guntermann U , Tan I , Hüttermann A
Published: January 2020

Alpha-Glucosidase of Myxobacter AL-1 was induced by the addition of maltose to a defined medium as the sole carbon source. This induction takes place during lag-phase conditions without concomitant growth; it seems not to be regulated by the mechanism of catabolite repression. Using the method of density labeling with deuterated amino acids and subsequent analysis by equilibrium density gradient centrifugation in metrizamide-2H2O gradients it could be shown that the activity increase of the enzyme during induction is the the result of a de novo synthesis of the enzyme protein. After a short pulse of induction with maltose, alpha-glucosidase exhibited a pattern of variation in enzyme activity during the cell cycle that was similar to the one observed after growth of the cells on maltose for several generations.
Transductional mapping of gene trmA responsible for the production of 5-methyluridine in transfer ribonucleic acid of Escherichia coli
Authors: Björk G R
Published: January 2020

The gene trmA, responsible for the production of 5-methyluridine (ribothymidine) in transfer ribonucleic acid, has been located at 79 min on the chromosomal map of Escherichia coli K-12. In five-factor crosses the gene order was shown to be argH-trmA-rif-thiA-metA. The co-transduction frequency between argH and trmA was 65%. Furthermore, the trmA5 mutation was shown to be recessive, in agreement with the notion that the trmA gene is the structural gene for the transfer tibonucleic acid (5-methyluridine) methyltransferase.
Effect of preparatory techniques on the gross morphology of Mycoplasma hominis
Authors: Robertson J , Gomersall M , Gill P
Published: January 2020

A method is presented whereby cells of Mycoplasma hominis can be prepared with minimal distortion for electron microscopy. After the addition of glutaraldehyde to broth cultures, incubation is continued for 1 h. The cells are then collected by centrifugation, washed in distilled water, and used for negative-contrast preparations.
Chromosome-plasmid interaction in Escherichia coli K-12 carrying a thermosensitive plasmid, Rts1, in autonomous and in integrated states
Authors: Yoshimoto H , Yoshikawa M
Published: January 2020

An Hfr strain of Escherichia coli K-12 was obtained by integrative suppression with a thermosensitive plasmid, Rts1. The R plasmid was integrated into the chromosome between rif and thr, and transfer of the chromosome occurred counterclockwise. The thermosensitivity of host cell growth due to the dnaA mutation was markedly but not completely reduced in this integratively suppressed Hfr strain. When the dnaA mutation was removed by transducing the dnaA+ genome to this Hfr, the thermosensitivity of cell growth due to existence of Rts1 was suppressed in contrast to strains carrying it autonomously. Thermosensitivity of cell growth appeared again when the plasmid was detached from the chromosome to exist autonomously. Contrary to the effect on cell growth, the transfer of the chromosome and the plasmid itself and the ability to "restrict" T-even phages were still thermosensitive in all of these strains carrying Rts1, irrespective of its state of existence. The detached plasmid as well as the original Rts1 were segregated upon growth at 42 C. These data are discussed in relation to chromosome-plasmid interaction. One of the most important conculusions is that some plasmid genes, related to their replication, are phenotypically suppressed by the chromosome when it is integrated.
Enzymology and genetic regulation of a cyclic nucleotide-binding phosphodiesterase-phosphomonoesterase from Aspergillus nidulans
Authors: Polya G M , Brownlee A G , Hynes M J
Published: January 2020

A cyclic nucleotide-binding phosphohydrolase that possesses both a phosphomonoesterase and a phosphodiesterase catalytic function has been partially purified from Aspergillus nidulans. The enzyme hydrolyzes both p-nitrophenylphosphate and bis-(p-nitrophenyl)-phosphate. o'-Nucleoside monophosphates are the best physiological phosphomonesterase substrates but 5'- and 2'-nucleoside monophosphates are also hydrolyzed. The enzyme catalyzes the hydrolysis of adenosine 5'-triphosphate, adenosine 5'-diphosphate, and 2',3'- and 3'5'-cyclic nucleotides, but not of ribonucleic acid, deoxyribonucleic acid, or nicotinamide adenine dinucleotide. The enzyme has acid pH optima and is not activated by divalent cations. Nucleosides and nucleotides inhibit the enzyme. Cyclic nucleotides are competitive inhibitors of the phosphodiesterase-phosphomonoesterase. The enzyme can occur extracellularly. The phosphodiesterase-phosphomonoesterase is present at high levels in nitrogen-starved mycelium, and it is strongly repressed during growth in media containing ammonium or glutamine and weakly repressed during growth in glutamate-containing medium. Experiments with various area mutants show that this regulatory gene is involved in the control of the enzyme. No evidence for regulation of the enzyme by carbon or phosphorus starvation has been found.
Inactivation of citrate lyase from Rhodopseudomonas gelatinosa by a specific deacetylase and inhibition of this inactivation by L-(+1-glutamate
Authors: Giffhorn F , Gottschalk G
Published: January 2020

A previously unrecognized enzyme, citrate lyase deacetylase, has been purified about 140-fold from cell extracts of Rhodopseudomonas gelatinosa. It catalyzed the conversion of enzymatically active acetyl-S-citrate lyase into the inactive HS-form and acetate. The enzyme exhibited an optimal rate of inactivation at pH 8.1. Because of the instability of acetyl-S-citrate lyase at acidic and alkaline pH values, all assays were carried out at pH 7.2, where the spontaneous hydrolysis of the acetyl-S-citrate lyase was negligible and deacetylase showed 70% of the activity at pH 8.1. The apparent Km value for citrate lyase was 10(-7) M at pH 7.2 and 30 C. The activity of the deacetylase was restricted to the citrate lyase from R. gelatinosa. The corresponding lyases from Enterobacter aerogenes (formerly Klebsiella aerogenes) and Streptococcus diacetilactis were not deacetylated; likewise, thioesters such as acetyl-S coenzyme A, acetoacetyl-S coenzyme A, and N-acetyl-S-acetyl-cysteamine were also not hydrolyzed. Citrate lyase deacetylase was present in very small amounts in cells of R. gelatinosa grown with acetate or succinate; it was induced by citrate along with the citrate lyase. L-(+)-Glutamate strongly inhibited the deacetylase. Fifty percent inhibition was obtained at a concentration of 1.4 X 10(-4) L-(+)-glutamate. D-(-)-Glutamate, alpha-ketoglutarate, L-alpha-hydroxyglutarate, L-(-)-proline, and other metabolites were less effective.
Genetic analyses of an amber mutation in Escherichia coli K-12, affecting deoxyribonucleic acid ligase and viability
Authors: Sato T , Horiuchi T , Nagata T
Published: January 2020

Genetic analyses of an Escherichia coli K-12 mutant possessing the amber mutation lig-321 were carried out. This mutant is defective in deoxyribonucleic acid (DNA) ligase and conditionally lethal. We constructed strains harboring an F'lig+ or F'lig-321 plasmid. Genetic complementation analyses were done by using these plasmids and by constructing a lig-4/F'lig-321 merodiploid. It was shown that lig-321 does not complement lig-4, unless the former is suppressed by an amber suppressor. The same was found to be the case between lig-321 and lig-ts7. Transductional mapping of lig-321, by a four-factor cross, revealed that lig-321 is very closely linked to lig-4. The frequency of recombinants between the two alleles was not unreasonable for assuming that they arose by intragenic recombination. The lig-4 and lig-ts7 alleles are known to reside in the structural gene for DNA ligase, in which lig-321 may also be located.
Compatibility of pTM89, a new F-like R factor, and of derivative plasmids
Authors: Monti-Bragadin C , Samer L
Published: January 2020

pTM89, an fi+ R factor that controls the production of repressed F-type pili, is incompatible with plasmids belonging to the FII and P groups. The results of P1 transduction show that all of the resistance markers of pTM89 are part of a single replicon, which also includes RTF. When the compatibility of different derivative plasmids was investigated, it was found that they fall into two classes. Those of the first class have lost the compatibility of pTM89 for the P group but are still incompatible with FII group, whereas those of the second class are compatible with plasmids of both groups. Plasmids of the latter class that are also compatible with each other and, therefore, apparently lack any determinant for compatibility are genetically stable and self-transmissible. It appears, therefore, that compatibility between plasmids cannot be explained by the hypothesis of competition for a maintenance site.
On the question of integration of Agrobacterium tumefaciens deoxyribonucleic acid by tomato plants
Authors: Hanson R S , Chilton M D
Published: January 2020

Treatment of tomato plants with Agrobacterium tumefaciens causes subsequently administered [3H]thymidine to be preferentially incorporated into a satellite deoxyribonucleic acid (DNA) whose buoyant density is between that of bacterial DNA (rho = 1.718 g/cm3) and plant main band DNA (rho = 1.692 g/cm3). Satellite DNA upon shearing or sonic treatment releases fragments of higher and lower buoyant density, as reported by earlier investigators. The satellite has no significant base sequence homology with A. tumefaciens DNA, for its rate of reassociation is not accelerated by the addition of high concentrations of the latter. Tomato DNA isolated from shoots or from leaf nuclei accelerates renaturation of labeled satellite DNA. We conclude that the intermediate density labeled DNA is a plant satellite and not the product of covalent joining of bacterial and plant DNA as suggested by earlier investigators.
trans-Recessive mutation in the first structural gene of the histidine operon that results in constitutive expression of the operon
Authors: Meyers M , Levinthal M , Goldberger R F
Published: January 2020

The first enzyme for histidine biosynthesis, encoded in the hisG gene, is involved in regulation of expression of the histidine operon in Salmonella typhimurium. The studies reported here concern the question of how expression of the histidine operon is affected by a mutation in the hisG gene that alters the allosteric site of the first enzyme for histidine biosynthesis, rendering the enzyme completely resistant to inhibition by histidine. The intracellular concentrations of the enzymes encoded in the histidine operon in a strain carrying such a mutation on an episome and missing the chromosomal hisG gene are three- to fourfold higher than in a strain carrying a wild-type hisG gene on the episome. The histidine operon on such a strain fails to derepress in response to histidine limitation and fails to repress in response to excess histidine. Furthermore, utilizing other merodiploid strains, we demonstrate that the wild-type hisG gene is trans dominant to the mutant allele with respect to this regulatory phenomenon. Examination of the regulation of the histidine operon in strains carrying the feedback-resistant mutation in an episome and hisT and hisW mutations in the chromosome showed that the hisG regulatory mutation is epistatic to the hisT and hisW mutations. These data provide additional evidence that the first enzyme for histidine biosynthesis is involved in autogenous regulation of expression of the histidine operon.
Induction of petite mutations during germination and outgrowth of Saccharomyces cerevisiae ascospores
Authors: Redshaw R A
Published: January 2020

The germination and outgrowth of Saccharomyces cerevisiae ascospores were studied by determining the sensitivity of the ascospores to the action of chemical mutagens. Survival of the ascospores after N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment was low during the first 2 h of germination and then increased and remained constant. Survival of the ascospores after 2-methoxy-6-chloro-9-(3-[ethyl-2-chloroethyl]aminopropylamino)acridine-2HC1 (ICR-170) treatment was constant from 0 to 5 h, but as the ascospores completed outgrowth at 6 h they became more sensitive to killing by ICR-170. Survival of the ascospores remained high during treatment with 2-methoxy-6-chloro-9-(3-[ethyl-2-hydroxyethyl]aminopropylamino)acridine-2HC1 (ICR-170-OH) or 2,7-diamino-10-ethyl-9-phenyl-phenanthridinium bromide. The main classes of mutations screened for were petites and auxotrophs. The induction of petites and auxotrophs by MNNG was independent of the stage of germination and outgrowth treated. Petite induction by ICR-170 was dependent upon the stage of germination and outgrowth treated. The early hours of germination (0 to 3 h) were not sensitive to petite induction. However, there was maximal petite induction at 5 h into germination and outgrowth, followed by a decline. During this same time period, ICR-170 induced less than 1% auxotrophic colonies. This finding is very unusual because ICR-170 induced 15% auxotrophic colonies in starved log-phase cultures of S. cerevisiae. The acridine ICR-170-OH induced no mutations during germination and outgrowth of the ascospores. Ethidium bromide induced petites, and the petite frequency became maximal at 5 h of germination and outgrowth, a result similar to that obtained with ICR-170.
Lipid-phase transitions of the strictly anaerobic bacteria Veillonella parvula and Anaerovibrio lipolytica
Authors: Verkley A J , Ververgaert P H , Prins R A , van Golde L M
Published: January 2020

As a basis for physicochemical studies on the membranes of the strictly anaerobic bacteria Veillonella parvula, Anaerovibrio lipolytica, and Megasphaera elsdenii, the fatty acyl and alk-1-enyl moieties on the phosphoglycerides of these organism were characterized. Uncommon is the high proportion of a heptadecenoic acyl and alk-1-enyl moiety in these three lactate-fermenting bacteria. In contrast to V. parvula and A. lipolytica, M. elsdenii contains high amounts of branched-chain acyl and alk-1-enyl moieties. Freeze-etching electron microscopy showed that the lipids of the plasma membranes of V. parvula and A. lipolytica go from the liquid crystalline to the gel state upon lowering of the temperature, indicating that the membrane lipids are predominantly in the fluid state. No lipid-protein segregation could be detected in the plasma membrane of M. elsdenii. This can be explained by the abundance of branched-chain fatty acyl and alk-1-enyl residues in the membranes of this organism which may prevent lipid-protein segregation during the lipid-phase transition.
Unusual Membranous Structures in Minicells and Minicell-Producing Strains of
Escherichia coli
Authors: Dennis Carolyn A. , Rogerson Allen C.
Published: January 2020

Minicell-producing strains of
Escherichia coli
K-12 seem to produce extra membranous material yielding internal cross membranes, “piggy-back” minicell forms, and unusual vesicles.
Spin-labeling studies on the lipids of psychrophilic, psychrotrophic, and mesophilic clostridia
Authors: Finne G , Matches J R
Published: January 2020

Spin-labeling studies were conducted to elucidate the viscosity and phase transition temperatures of lipids isolated from psychrophilic, psychrotrophic, and mesophilic clostridia. Electron spin resonance spectroscopy indicated that the lipids, for all the growth temperatures tested, were in a fluid state and from 13 to 24 C higher than the corresponding lipid transition temperatures. When the organisms were grown at different temperatures, a psychrotropic and two mesophilic clostridia were shown to be able to adjust their lipid-phase transition temperature to the growth temperature. A psychrophilic Clostridium strain, when grown at different temperatures, synthesized lipids that had the same phase transition temperature. It is suggested that this lack of growth temperature-inducible regulation of lipid-phase transition temperature may be a molecular determinant for the psychrophily of this organism. It is proposed that the growth temperature range of an organism is dependent upon the ability of the organism to regulate its lipid fluidity within a specific range.
Thermosensitive mutations affecting ribonucleic acid polymerases in Saccharomyces cerevisiae
Authors: Thonart P , Bechet J , Hilger F , Burny A
Published: January 2020

Among 150 temperature-sensitive Saccharomyces cerevisiae mutants which we have isolated, 15 are specifically affected in ribonucleic acid (RNA) synthesis. Four of these mutants exhibit particularly drastic changes and were chosen for a more detailed study. In these four mutants, RNA synthesis is immediately blocked after a shift at the nonpermissive temperature (37 C), protein synthesis decays at a rate compatible with messenger RNA half-life, and deoxyribonucleic acid synthesis increases by about 40%. All the mutations display a recessive phenotype. The segregation of the four allelic pairs ts-/ts+ in diploids is mendelian, and the four mutants belong to three complementation groups. The elution patterns (diethylaminoethyl-Sephadex) of the three RNA polymerases of the mutants grown at 37 C for 3.5 h show very low residual activities. The in vitro thermodenaturation confirms the in vivo results; the half-lives of the mutant activities at 45 C are 10 times smaller than those of the wild-type enzymes. Polyacrylamide gel electrophoresis shows that the synthesis of all species of RNA is thermosensitive. The existence of three distinct genes, which are each indispensable for the activity of the three RNA polymerases in vivo as well as in vitro, strongly favors the hypothesis of three common subunits in the three RNA polymerases.
Patterns of spore locations in pairs of Bacillus cereus sporangia
Authors: Hitchins A D
Published: January 2020

The location patterns, relative to the cross wall, of terminal-to-subterminal Bacillus cereus spores were determined in pairs of sporangia. The presence of three types of patterns suggests that spores are randomly located, but medium-dependent variability of the frequency ratios of the patterns strongly suggests that nonrandom localization cannot be discounted.
Cell Cycle-Specific Incorporation of Lipoprotein into the Outer Membrane of
Escherichia coli
Authors: James Richard , Gudas Lorraine J.
Published: January 2020

A cell cycle-specific incorporation of free lipoprotein into the outer membrane of
Escherichia coli
was observed, with a maximal rate of incorporation occuring at the time of septation.
Cytochrome abnormalities and cyanide-resistant respiration in extranuclear mutants of Aspergillus nidulans
Authors: Turner G , Rowlands R T
Published: January 2020

The cytochrome spectra of two extranuclear mutants of Aspergillus nidulans and the double-mutant recombinant formed from them have been examined both at room temperature and at the temperature of liquid N2 and compared with those of the wild-type strain. The oligomycin-resistant, slow growing mutant contained an increased amount of cytochrome c without any loss of cytochromes b and a,a3. The cold-sensitive mutant, apparently normal when grown at 37 C, showed an increased amount of cytochrome c and a partial loss of cytochromes b and a,a3 when grown at 20 C. A combination of these effects was observed in the double-mutant recombinant. Cyanide-resistant respiration was present in both mutant strains and in the recombinant at much higher levels than in the wild-type strain. In the oligomycin-resistant mutant, this was usually present together with cyanide-sensitive respiration, whereas in the cold-sensitive mutant and recombinant grown at 20 C cyanide-resistant approached 100%. Inhibitor and growth yield studies indicated that the cyanide-resistant pathway was not used by the cold-sensitive mutant during growth at 20 C.
Mutant of Escherichia coli defective in response to colicin K and in active transport
Authors: Plate C A
Published: January 2020

A mutant of Escherichia coli has been isolated that grows poorly on succinate and exhibits a markedly reduced sensitivity to colicin K. This mutant is also deficient in the respiration-linked transport of proline and thiomethyl-beta-D-galactoside but appears normal for the adenosine triphosphate-dependent transport of glutamine and arginine. A temperature-conditional revertant of the mutant grows on succinate and is sensitive to colicin K at 27 C, but fails to grow on succinate and is insensitive to colicin K at 42 C. Proline transport in the temperature-conditional revertant is reduced at 42 C when either glucose or succinate is used as energy source. Glutamine transport, on the other hand, is normal at 42 C with glucose as energy source, but is reduced with succinate, although not to the same extent as is proline transport. The lack of growth on succinate and the deficiencies in transport at 42 C are not due to a temperature-dependent lesion in either the electron transport chain or in Ca2+, Mg2+-activated adenosine triphosphatase activity. Membrane vesicles prepared from the temperature-conditional revertant are impaired in proline transport at both 27 and 42 C. These findings suggest the existence in the cytoplasmic membrane of E. coli cells of a component, presumably protein, that is required for colicin K action and that functions in respiration-linked and, to a lesser degree, in adenosine triphosphate-dependent active transport systems. This protein may serve as the primary target of colicin K action.
Suppressor-induced structural changes in a missense L-ribulokinase of Escherichia coli
Authors: Cribbs R M , Leonard J C , Rickelton A H
Published: January 2020

A suppressor mutation specific for a missense codon in the L-ribulokinase structural gene of the L-arabinose operon of Escherichia coli B/r enhanced L-arabinose utilization by the strain containing the missense codon. Electrophoretic comparisons of the wild-type, missense, and suppressed missense L-ribulokinases indicated that the suppressor changed the structure of the missense kinase, thereby increasing its catalytic activity. Hyperinducibility imposed on an operator-distal gene by the missense codon was not affected by the suppressor mutation.
Analytical isoelectric focusing of R factor-determined beta-lactamases: correlation with plasmid compatibility
Authors: Matthew M , Hedges R W
Published: January 2020

R factor-determined beta-lactamases have been investigated by analytical isoelectric focusing. The enzymes such as those specified by the R6K and RP4 plasmids (TEM-type enzymes) are notably homogenous in biochemical tests (Hedges et al., 1974), but two subclasses can be distinguished by isoelectric focusing. Three subclasses can be distinguished among the oxacillin-hydrolyzing enzymes, in good agreement with the classification based upon biochemical characteristics (Dale and Smith, 1974). The TEM-type beta-lactamases are promiscuously distributed among plasmids of a wide variety of compatibility groups, whereas the various oxacillin-hydrolyzing enzymes show some degree of correlation with compatibility.
Physical properties of L-asparaginase from Serratia marcescens
Authors: Stern M L , Phillips A W , Gottlieb A J
Published: January 2020

Purified L-asparaginase from Serratia marcescens had an apparent-weight average molecular weight of 171,000 to 180,000 as determined by electrophoresis on polyacrylamide gels and by sedimentation equilibrium at low speed in an analytical ultracentrifuge. A subunit molecular weight of 31,500 +/- 1,500 was estimated for the enzyme after treatment with sodium dodecyl sulfate and urea and electrophoresis on polyacrylamide gels; a similar value was obtained by high-speed sedimentation equilibrium in the presence of guanidine hydrochloride. Our data indicate that the Serratia enzyme could have five or six subunits of 32,000 daltons, compared to four subunits of 32,000 daltons in the Escherichia coli enzyme. The Serratia L-asparaginase also appears to be a larger molecule than the enzyme from Erwinia carotovora, Proteus vulgaris, Acinetobacter glutaminasificans, and Alcaligenes eutrophus. The Serratia enzyme, like that from E. caratovora, was more resistant than the E. coli enzyme to dissociation by sodium dodecyl sulfate. This resistance could be due to the finding that the Serratia enzyme had a relatively high hydrophobicity, similar to the enzyme from E. caratovora, when compared with the hydrophobicity of the E. coli enzyme. The isoelectric point of the Serratia enzyme was approximately 5.2. The influence of certain physical characteristics of the enzyme on the biological properties is discussed.
Bacteriophage Mu-1-induced mutation to mutT in Escherichia coli
Authors: Conrad S E , Dussik K T , Siegel E C
Published: January 2020

Of approximately 10,000 independent phage Mu-1 lysogens, 3 had a mutator phenotype. One (mutation designated mut-49) resembled mutT1 in the frequency and types of mutations induced. mut-49 was mapped between leu and ace and was not separable from the Mu prophage. mut-49 was recessive and did not complement mutT1. mut-49, like mutT1, did not increase the reversion of the frameshift mutation lac Z (ICR48). mut-49 and mutT1 induced the same two classes of trpA78 revertants, indicating that mut-49 induced adenine-thymine leads to cytosine-guanine transversions. The results support previous work indicating that the mutational specificity of mutT is gene and not allele specific.
Translocation in Bacillus subtilis: characterization of elongation factor G by peptidyl-[3H]puromycin synthesis
Authors: Aharonowitz Y , Ron E Z
Published: January 2020

This communication describes the characterization of elongation factor G from Bacillus subtilis by the translocation of "native" peptide donors. Translocation was followed by elongation factor G-dependent increase in the synthesis of peptidyl-[3H]puromycin using "washed" ribosomes carrying in vivo-bound peptidyl-transfer ribonucleic acid ("native" peptidyl-transfer ribonucleic acid) molecules as peptide donors. Such ribosomes were obtained from cell extracts by washing at a high salt concentration. The use of "native" peptide donors facilitated the study of translocation under conditions that are closer to the in vivo state than those in the methods previously employed.
Role of D-tryptophan oxidase in D-tryptophan utilization by Escherichia coli
Authors: Hadar R , Slonim A , Kuhn J
Published: January 2020

Mutants of Escherichia coli K-12 that require L-tryptophan (trp) are normally unable to utilize D-tryptophan to fulfill their requirement. However, secondary mutations (dadR) that confer this ability can be isolated. In such strains two distinct enzymes are found to be produced at high levels: D-amino acid oxidase (EC 1.4.3.3) and D-tryptophan oxidase. A convenient assay procedure for D-tryptophan oxidase is described. The two enzymes could be distinguished on the basis of their sensitivity to inhibition by L-phenylalanine and L-tyrosine. Strains that were trp dadR could not grow with D-tryptophan in the presence of L-phenylalanine, but further mutations, Fyo, could be isolated that allowed growth under these conditions. Some of them were characterized by further increases in the level of D-tryptophan oxidase activity and a sharp decrease in D-amino acid oxidase. These kinds of Fyo mutations lay in or near the dadR gene. The substrate specificity of the two enzymes toward a large number of compounds was examined. The transamination of aromatic keto acids was investigated. In the wild-type strain only a single enzyme, transaminase A (EC 2.6.1.5), was found, and it was irreversibly activated when subjected to elevated temperatures. The present state of our knowledge on D-amino acid utilization in E. coli is summarized.