Repression and activation of promoter-bound RNA polymerase activity by Gal repressor

Hyon E. Choy, Robert R. Hanger, Tsunehiro Aki, Michael Mahoney, Katsuhiko Murakami, Akira Ishihama, Sankar Adhya

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35 Scopus citations

Abstract

By binding to the DNA site O(E) at position -60.5 in the gal operon, the GalR protein activates transcription from the P2 promoter located on the opposite face of DNA (position -5) and represses transcription from the P1 promoter located on the same face (position +1). GalR increases RNA polymerase binding at P2 and inhibits isomerization at P1 by forming a GalR-DNA-RNA polymerase ternary complex in each case. The specific effect of GalR at one promoter is independent of the presence of the other promoter. The enhancement or repression is also not the intrinsic property of a promoter; the regulation can be reversed by switching the angular orientation of the promoters relative to O(E). Both enhancement and repression appear to require the same interaction between RNA polymerase α-subunit and GalR and/or the same interaction between RNA polymerase α-subunit and DNA in the ternary complexes. We have discussed how GalR might exert opposite effects in the steps involved in the formation of the open complex from free RNA polymerase and DNA.

Original languageEnglish (US)
Pages (from-to)293-300
Number of pages8
JournalJournal of Molecular Biology
Volume272
Issue number3
DOIs
StatePublished - Sep 26 1997

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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