Regulation of RNA polymerase subunit synthesis in Escherichia coli: utilization of DNA-Intercalating drugs as a probe

Chao, L.

Archives of Biochemistry and Biophysics 183(1): 242-249

1977


ISSN/ISBN: 0003-9861
PMID: 334079
DOI: 10.1016/0003-9861(77)90437-4
Accession: 068526474

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Abstract
The effect of 4 DNA-intercalating drugs on the synthesis of the .beta. and .beta.' subunits of E. coli RNA polymerase [EC 2.7.7.6] was investigated. Acridine orange, proflavine, ethidium bromide and berberine sulfate at sublethal doses caused a general reduction in cellular RNA and protein syntheses. Under this condition, acridine orange and proflavine rapidly led to overproduction of the .beta. and .beta.' subunits in significant amounts. Ethidium bromide and berberine sulfate also caused overproduction of the 2 subunits but with a delay of 10 min at 30.degree. C. The .beta. and .beta.' subunits of RNA polymerase became the major proteins being synthesized by E. coli cells after prolonged treatment with DNA-intercalating drugs. The level of the .alpha. subunit of RNA polymerase was not altered by any of the drugs tested. The overproduction of the .beta. and .beta.' subunits induced by DNA-intercalating drugs required de novo synthesis of the .beta.beta.' mRNA. Apparently, the expression of the .beta.beta.' operon is regulated and the synthesis of the .alpha. subunit is not regulated by the mechanism regulating the .beta.beta.' operon. These and other results strongly suggest that the concentration of intracellular free RNA polymerase plays a role in regulating the expression of the .beta.beta.' operon.