Biomedical subjects

R M Blumenthal

Publications and source records attributed to R M Blumenthal.

43 records · Page 3Linked to original sources

PubMed1981

Proteins Specified by bovine herpesvirus 1 (infectious bovine rhinotracheitis virus).

An electrophoretic analysis of radioactively labeled, purified, "empty" and DNA-containing infectious bovine rhinotracheitis virions revealed the presence of 25 to 33 structural (virion) polypeptides. A total of 11 of these polypeptides could be labeled with [3H]glucosamine and were identified as glycoproteins. In addition to the 25 structural polypeptides, infectious bovine rhinotracheitis virus infected cells also contained at least 15 nonstructural (nonvirion) polypeptides that were not present in purified virions. Expression of the viral polypeptides in infected cells was controlled temporally. Thus, most viral polypeptides could be categorized as "alpha" (immediate early), "beta" (early), or "gamma" (late) on the basis of their order of appearance in infected cells and whether their syntheses were dependent upon prior viral protein or DNA synthesis. None of the glycoproteins belongs to the alpha class, although at least one (GVP11) was synthesized in the absence of viral DNA synthesis. Serum from a cow in which infectious bovine rhinotracheitis virus lesions were reactivated by dexamethasone precipitated both structural and nonstructural polypeptides.

Animals↗

PubMed1980

Gene expression in Escherichia coli after amino acid, purine, or pyrimidine exhaustion.

Three strains of Escherichia coli B auxotrophic for leucine, guanine, or uracil were analyzed after exhaustion of the respective required nutrient from the growth medium. The pattern of transcription was analyzed by ribonucleic acid-deoxyribonucleic acid filter hybridization to specific deoxyribonucleic acid probes, and the pattern of translation was analyzed by autoradiography after the resolution of proteins on sodium dodecyl sulfate-polyacrylamide gels. The results obtained suggest the following conclusions. (i) Specific regulation of rpoBC transcription occurs at both the promoter (PL10) and the putative attenuator between rplL and rpoB. (ii) The stringent response of ribosomal protein gene expression to amino acid insufficiency is only partially mimicked by purine or pyrimidine insufficiency. (iii) Transcription initiation at PL10 decreases in response to guanine exhaustion, but in contrast increases significantly in response to uracil exhaustion. (iv) The expression of the induced lac operon is severely depressed during any of these exhaustions. These conclusions argue against simple models for regulation of ribonucleic acid polymerase production or promoter choice by the intracellular levels of its substrate nucleotides.

DNA-Directed RNA Polymerases↗

PubMed1980

Regulation of ribonucleic acid polymerase synthesis during restriction of an Escherichia coli mutant temperature sensitive for transcription factor sigma.

An Escherichia coli mutant temperature sensitive for the sigma subunit of ribonucleic acid polymerase was shifted to restrictive temperatures. In response to these restrictions the transcription of rpoBC increased markedly, and the synthesis rates of the beta and beta' subunits of ribonucleic acid polymerase increased. The ratio of the beta and beta' synthesis rates (beta/beta') decreased.

DNA-Directed RNA Polymerases↗

PubMed1978

Gene expression in Escherichia coli B/r during partial rifampicin-mediated restrictions of transcription initiation.

The antibiotic rifampicin inhibits transcription initiation, but not the elongation and completion of nascent RNA transcripts. Addition of low concentrations of rifampicin only partially blocks initiation but at the same time specifically alters the general pattern of transcription in the culture. The transcription of genes specifying the beta and beta' subunits of RNA polymerase, and to a lesser extent of the genes specifying the RNA and protein components of the ribosome, was specifically stimulated relative to total transcription. In contrast, the transcription of the lactose operon was selectively reduced. These results are consistent with the ideas that the level of expression of the genes specifying the beta and beta' subunits is sensitive to the general rate of RNA synthesis in the culture, and that the expression of the beta and beta' RNA polymerase genes is related to the expression of ribosome component genes.

DNA-Directed RNA Polymerases↗

PubMed1976

The effects of the relA gene on the synthesis of aminoacyl-tRNA synthetases and other transcription and translation proteins in Escherichia coli A.

The effects of a partial restriction of valyl-tRNA aminoacylation on the synthesis of aminoacyl-tRNA synthetases, ribosomal proteins, and other translation and transcription proteins were examined in otherwise isogenic stringent (relA+) and relaxed (relA1) derivatives of E. coli B. The synthesis of individual ribosomal proteins, elongation factor G, and to a lesser extent elongation factors Tu and Ts, and the valyl- and arginyl-tRNA synthetases was found to be subject to the influence of the stringent control system. The synthesis of the alpha and beta subunits of RNA polymerase and several of the aminoacyl-tRNA synthetases, in contrast, is either not subject to the influence of the stringent control system, or is subject to additional regulatory constraints.

Amino Acyl-tRNA Synthetases↗

PubMed1976

A mutant of Escherichia coli with an altered elongation factor Tu.

A previously isolated mutant of E. coli K12 HAK 88 [Kuwano, M., Endo, h & yamamoto, M. (1972) J. Bacteriol, 112, 1150-1156], contains a new protein that in two-dimensional gel electropherorgrams has the same molecular weight as normal elongation factor Tu, but whose isoelectric point is altered approximately 0.1 pH unit in the acidic direction. Peptide mapping, purification properties and the ratio of leucyl plus isoleucyl to methionyl plus cysteinyl residues of the normal elongation factor Tu protein and the new protein show a close similarity between the two. The mutation causing the altered electrophoretic mobility is located between argH and rif (79 min on the E. coli genetic map). These biochemical and genetic data indicate that strain HAK 88 has a mutationally altered tufB gene.

Chromosome Mapping↗

PubMed1976

Regulation of transcription factor rho and the alpha subunit of RNA polymerase in Escherichia coli B/r.

Transcriptional termination factor rho, the alpha subunit of RNA polymerase (RNA nucleotidyltransferase nucleosidetriphosphate: RNA nucleotidyltransferase, EC 2.7.7.6), and ribosomal protein S6 were resolved from whole-cell extracts of E. coli B/r by a high-resolution, two-dimensional polyacrylamide gel electrophoretic technique, and were identified through coelectrophoresis with the purified proteins. The regulation of rho, alpha, and S6 was studied, in steady-state cultures of E. coli B/r growing at rates ranging from 0.6 to 2.1 generations per hr, through the use of this gel technique and a double radioisotope labeling procedure. The regulatory patterns of rho and alpha are distinct from, but similar to, one another. Neither rho nor alpha shows the sharply increasing levels with increasing growth rate shown by the ribosomal proteins was exemplified by S6. The difference between the levels of rho and alpha, on the one hand, and S6, on the other, is most pronounced during rapid growth. The regulatory pattern of alpha is interesting, given the recent suggestion that the gene coding for alpha is contranscribed with genes coding for ribosomal proteins.

Bacterial Proteins↗