PMID: 7009598Mar 25, 1981Paper

A direct effect of guanosine tetraphosphate on pausing of Escherichia coli RNA polymerase during RNA chain elongation.

The Journal of Biological Chemistry
R E KingstonM J Chamberlin

Abstract

The effect of the regulatory nucleotide ppGpp on transcription by Escherichia coli RNA polymerase in vitro has been studied using bacteriophage T7 and T3 DNAs as templates. We have previously described the development of transcriptional test systems using these templates that can sensitively detect changes in promotor or terminator recognition of an RNA polymerase (Wiggs, J.L., Bush, J.W., and Chamberlin, M.J. (1979) Cell 16, 97-109) or changes in the rate of any of the major steps of the transcription cycle (Chamberlin, M.J., Nierman, W.C., Wiggs, J.L., and Neff, N. (1979) J. Biol. Chem. 254, 10061-10069). Using these procedures we fail to detect any substantial alteration by ppGpp of the normal interaction of E. coli RNA polymerase with the several T7 major and minor promoter sites or of the rate of productive RNA chain initiation at either T7 promoter A1 (ATP start) or A2 (GTP start). However, at physiologically relevant concentrations (KI approximately 50 microM), ppGpp significantly lowers the overall elongation rate of T7 RNA chains, leading to a substantial reduction in the overall rate of RNA synthesis. Inhibition of transcriptional elongation does not appear to be competitive with the ribonucleoside triphosphate substr...Continue Reading

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