期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 311, 期 2, 页码 265-282出版社
ACADEMIC PRESS LTD
DOI: 10.1006/jmbi.2001.4842
关键词
RNA polymerase; pausing; transcriptional regulation; RNA : DNA hybrid
资金
- NIGMS NIH HHS [GM 38660] Funding Source: Medline
Human RNA polymerase II recognizes a strong transcriptional pause signal in the initially transcribed region of HIV-1. We report the use of a limited-step transcription assay to dissect the mechanism underlying recognition of and escape from this HIV-1 pause. Our results suggest that the primary determinant of transcriptional pausing is a relatively weak RNA:DNA hybrid that triggers backtracking of RNA polymerase II along the RNA and DNA chains and displaces the RNA 3 ' OH from the active site. In contrast, two alternative RNA secondary structures, TAR and anti-TAR, are not required for pausing and affect it only indirectly, rather than through direct interaction with RNA polymerase II. TAR accelerates escape from the pause, but anti-TAR inhibits formation of TAR prior to pause escape. The behavior of RNA polymerase II at a mutant pause signal supports a two-step, non-equilibrium mechanism in which the rate-determining step is a conformational. change in the enzyme, rather than the changes in nucleic-acid base-pairing that accompany backtracking. (C) 2001 Academic Press.
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