Nucleic Acids Research, 1981, Vol. 9, No. 4 1005-1018
© 1981
MOLECULAR BIOLOGY |
On the mechanism of inhibitory effect of violamycin antibiotics on the transcription by bacteriophage T3-induced RNA polymerase
Institut fü Mikrobiologie, Abteilung Biochemie, Humboldt-Universität Berlin DDR-1080 Berlin, Clara-Zetkin-Strasse 96 Akademie der Wissenschaften der DDR, Forschungszentrum für Molekularbiologie und Medizin, Zentralinstitut für Mikrobiologie und experimentelle Therapie DDR-6900 Jena, GDR
Received November 4, 1980. The effect of three components of the anthracycline antibiotic violamycin on the transcription of bacteriophage T3 DNA by bacteriophage T3-induced RNA polymerase has been investigated in a cell-free system. The glycosides of violamycin BI possess the highest inhibitory activity, whereas those of violamycin BII and violamycin A show a reduced inhibitory effect. Concentrations of violamycin BI depressing the incorporation of (3H)UMP into RNA chains have only a slight effect on the binding of the T3 RNA polymerase to T3 DNA and on the incorporation of GTP as the first nucleotide. This shows that the primary target of the antibiotic is not the initiation of the RNA synthesis. The binding of violamycin BI to T3 DNA causes a strong reduction of the elongation rate of the RNA chains.