T7 RNA polymerase elongation complex structure and movement

Jianbin Huang, Rui Sousa

Research output: Contribution to journalArticle

63 Scopus citations

Abstract

We have characterized T7RNAP elongation complexes (ECs) halted at different positions on a single template using a combination of digestion with exonuclease III, λ exonuclease, RNAse T1, and treatment with KMnO4. Our results indicate that the transcription bubble is approximately nine bases long and that the RNA:DNA hybrid is 7-8 bp in size. An additional four to six bases of RNA immediately 5' to the hybrid interact with the RNAP, probably with a site on the N-terminal domain. When ECs with transcripts of different length were probed in the presence or absence of the incoming NTP we found that the position of the EC on the template and the RNA shifted downstream upon NTP binding. NTP binding also restricted the lateral mobility of the complex on the template. Our results indicate that, in the absence of bound NTP, the RNAP is relatively free to slide on the template around a position that usually lies one to two bases upstream of the position from which NTP binding and bond formation occur. NTP binding stabilizes the RNAP in the post-translocated position and keeps it from sliding upstream, either due directly to RNAP:NTP:template interactions, or to an isomerization which causes the fingers subdomain of the RNAP to clamp down on the downstream end of the template strand. (C) 2000 Academic Press.

Original languageEnglish (US)
Pages (from-to)347-358
Number of pages12
JournalJournal of Molecular Biology
Volume303
Issue number3
DOIs
StatePublished - Oct 27 2000

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Keywords

  • Elongation
  • Motor proteins
  • RNA polymerase
  • Transcription
  • Translocation

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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