The structural mechanism of translocation and Helicase activity in t7 RNA polymerase

Y. Whitney Yin, Thomas A. Steitz

Research output: Chapter in Book/Report/Conference proceedingChapter


RNA polymerase functions like a molecular motor that can convert chemical energy into the work of strand separation and translocation along the DNA during transcription. The structures of phage T7 RNA polymerase in an elongation phase substrate complex that includes the incoming nucleoside triphosphate and a pretranslocation product complex that includes the product pyrophosphate (PPi) are described here. These structures and the previously determined posttranslocation elongation complex demonstrate that two enzyme conformations exist during a cycle of single nucleotide addition. One orientation of a five-helix subdomain is stabilized by the phosphates of either the incoming NTP or by the product PPi. A second orientation of this subdomain is stable in their absence and is associated with translocation of the heteroduplex product as well as strand separation of the downstream DNA. We propose that the dissociation of the product PPi after nucleotide addition produces the protein conformational change resulting in translocation and strand separation.

Original languageEnglish (US)
Title of host publicationStructural Insights into Gene Expression and Protein Synthesis
PublisherWorld Scientific Publishing Co.
Number of pages12
ISBN (Electronic)9789811215865
ISBN (Print)9789811215858
StatePublished - Jan 1 2020
Externally publishedYes

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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