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Biomedical subjects

F Reusser

Publications and source records attributed to F Reusser.

At least 37 records · Page 2Linked to original sources
PubMed1979

Inhibition of ribosomal and RNA polymerase functions by rubradirin and its aglycone.

The antibiotic rubradirin is structurally related to the ansamycin family of antibiotics. Most members of this group act as specific inhibitors of bacterial RNAP. Rubradirin and its aglycone possess diverging modes of action. Rubradirin inhibits ribosomal functions related to the peptide chain initiation process. It does not inhibit RNAP. By contrast the aglycone of rubradirin retains moderate inhibitory activity towards ribosomal functions but acts essentially as an extremely potent inhibitor of RNAP.

Anti-Bacterial Agents↗
PubMed1978

DNA sequences of promoter regions for the str and spc ribosomal protein operons in E. coli.

The DNA sequences have been determined for promoter regions of two ribosomal protein operons in E. coli, the str operon and the spc operon. The site of in vitro transcription initiation within each of these promoter regions has been determined. The start site of the str operon occurs 69 bases upstream from the initiation codon of the S12 gene. The start site of the spc operon occurs 72 bases upstream from the L14 gene, and only 91 bases downstream from the termination codon of the S17 gene (which is in the preceding S10 operon). Both promoters are similar to other sequenced promoters in that they each have an identifiable "Pribnow box" sequence 5 bases upstream from the transcription start site. The spc promoter has a long sequence of 2 fold symmetry centered within the Pribnow box; the str promoter has a shorter but similar symmetry. At positions -69 through -40 in the spc operon, another long region of symmetry is present which may be the termination signal of the preceding S10 operon. Extensive sequence similarity between the str and spc promoter regions is found downstream from the Pribnow box-that is, in a transcribed region preceding the translation start sites.

Bacterial Proteins↗
PubMed1977

Ficellomycin and feldamycin; inhibitors of bacterial semiconservative DNA replication.

The two peptide-like antibiotics ficellomycin and feldamycin impair semiconservative DNA replication but not DNA repair synthesis in bacteria. Specifically both antibiotics cause the accumulation of a 34S DNA species in toluenized Escherichia coli cells which lacks the capability of being integrated into larger DNA pieces and eventually the complete bacterial chromosome. Novobiocin, a known inhibitor of replicative DNA synthesis, was investigated for comparative purposes. The action of this latter antibiotic differs from the ones exerted by ficellomycin and feldamycin in the novobiocin appears to block an event associated with the initiation of Okazaki fragments. The fact that novobiocin impairs DNA gyrase suggests that this enzyme plays an essential role during the initiation of Okazaki pieces.

Anti-Bacterial Agents↗
PubMed1976

Tirandamycin, an inhibitor of bacterial ribonucleic acid polymerase.

The antibiotic tirandamycin (a 3-acyltetramic acid structurally related to streptolydigin) specifically inhibits transcription by interfering with the function of bacterial ribonucleic acid polymerase. Ribonucleic acid polymerases from rat liver nuclei are not subject to tirandamycin inhibition. Qualitatively, the mode of action of the antibiotic is identical to that of streptolydigin in inhibiting chain initiation as well as chain elongation during the transcriptional process. However, tirandamycin is approximately 40 times less potent than streptolydigin. The structures of the 3-acyl groups of the two acyltetramic acid antibiotics tirandamycin and streptolydigin differ only slightly in the degree of oxidation of the terminal dioxabicyclo (3.1)nonane system and possess the same stereochemistry (D. J. Duchamp, A. R. Branfman, A. C. Button, and K. L. Rinehart, 1973). More significantly, major differences occur at the 1 and 5 positions of the tetramic acids. Tirandamycin contains no substituents; streptolydigin contains a substituted acetamide function at position 5 and a sugar moiety at position 1. The lack of substituents at the 1 and 5 positions of the tetramic acid portion in tirandamycin is probably responsible for the reduced biopotency of tirandamycin as compared with streptolydigin.

Animals↗
PubMed1976

Antibiotics produced by Streptomyces ficellus II. Feldamycin and nojirimycin.

Feldamycin, a new antibacterial agent, and nojirimycin, a previously described antibiotic have been isolated from cultures of Streptomyces ficellus. Feldamycin, C17H25N7O5, is an amphoteric compound which inhibits a variety of bacteria in vitro but is found to be ineffective in the treatment of experimental bacterial infections in mice. Nojirimycin (5-amino-5-deoxy-D-glucose) has been isolated previously from cultures of several species of streptomycetes.

Animals↗
PubMed1976

Effect of spectinomycin on peptide chain initiation.

Spectinomycin inhibits the formation and causes dissociation of performed specific cell-free initiation complexes prepared with the trinucleotide A-U-G or R17 phage RNA, fmet-RNAF and either 30S ribosomal subunits or 70S ribosomes. Both the initiation factor and the Mg2+-induced processes are subject to inhibition by spectinomycin. The only exception is the Mg2+-induced 70S initiation system formed with A-U-G which is stimulated by spectinomycin.

Cell-Free System↗
PubMed1975

Steffimycin B, a DNA binding agent.

The antibiotic steffimycin B binds to double-stranded DNA as evidenced by difference spectroscopy and an increase of the thermal stability of DNA in the presence of the antibiotic. Salmon sperm DNA-steffimycin B complexes show a drastic decrease in template activity for Escherichia coli DNA polymerase I but not for DNA-idrected RNA polymerase. The differences in template properties of poly[d(A-T)] and poly (dG) - poly(dC)-antibiotic complexes,respectively, for DNA polymerase I and RNA polymerase suggest that the antibiotic interacts primarily with adenine or thymine bases or both in double-stranded DNA.

Animals↗
PubMed1975

Effect of lincomycin and clindamycin on peptide chain initiation.

Lincomycin does not affect initiation factor-dependent formation of 70S initiation complexes formed with fmet-tRNA(F), the initiation triplet A-U-G, and 70S ribosomes, whereas its 7-chloro-derivative clindamycin substantially stimulates this process. Conversely, lincomycin stimulates nonenzymatic formation of the 70S complex, but clindamycin does not. Both antibiotics stimulate the assembly of non-enzymatically formed 70S initiation complexes with R(17) phage ribonucleic acid and exert little effect on those formed in the presence of initiation factors. The formation of 30S initiation complexes is stimulated or remains unaffected by lincomycin or clindamycin except when initiation occurs in the presence of very low Mg(2+) concentrations. In this case, both antibiotics inhibit the assembly of the 30S complexes regardless of the messenger present.

Clindamycin↗