Reduction in abortive transcription from the lambdaPR promoter by mutations in region 3 of the sigma70 subunit of Escherichia coli RNA polymerase.

The Journal of Biological Chemistry
Ranjan SenNobuo Shimamoto

Abstract

Transcription initiation by Escherichia coli RNA polymerase at most promoters is associated with a reiterative synthesis and release of short abortive RNA products. We have investigated the mechanism of abortive RNA synthesis by using holoenzymes containing mutant sigma70 subunits with changes in region 3 (S506F and P504L), which reduce the ratio of abortive to full-length products. Binary complexes formed by these mutant enzymes at a modified lambdaPR promoter contained a smaller fraction of open complexes than for normal polymerase, suggesting an involvement of region 3 in melting duplex DNA or in maintenance of the open complex. The half-lives of the majority of binary complexes formed by the mutant enzymes were less than 1 min, in contrast to 30 min for the wild-type complexes. The time courses of transcription and pulse-labeling assays showed that moribund complexes, which generate only abortive products (Kubori, T., and Shimamoto, N. (1996) J. Mol. Biol. 256, 449-457), were formed by the mutant enzymes. However, they accumulated to a lesser extent than for the wild-type enzyme, due both to faster dissociation and conversion into inactive complexes. This is the main cause of the low degree of abortive transcription display...Continue Reading

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Citations

Mar 16, 2007·Plant Cell Reports·Eugene A Lysenko
Jun 8, 2002·Journal of Molecular Biology·Ronald S Johnson, Rebecca E Chester
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Mar 24, 2006·Molecular Microbiology·Motoki SusaNobuo Shimamoto
Feb 21, 2002·The Journal of Biological Chemistry·Motoki SusaNobuo Shimamoto
Sep 21, 2013·The Journal of Biological Chemistry·Satamita Samanta, Craig T Martin
Feb 7, 2001·The Journal of Biological Chemistry·R SenN Shimamoto
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Nov 25, 2016·Frontiers in Molecular Biosciences·Jookyung Lee, Sergei Borukhov
Sep 1, 2008·EcoSal Plus·Lilian M Hsu
Oct 3, 2021·Proceedings of the National Academy of Sciences of the United States of America·Ruth M SaeckerSeth A Darst

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