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Updated: Aug 16, 2026

High-throughput Purification of Affinity-tagged Recombinant Proteins
Published on: August 26, 2012
NTP-driven translocation and regulation of downstream template opening by multi-subunit RNA polymerases
Zachary F Burton1, Michael Feig, Xue Q Gong
1Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI 48824, USA. burton@msu.edu
Abstract:
Multi-subunit RNA polymerases bind nucleotide triphosphate (NTP) substrates in the pretranslocated state and carry the dNMP-NTP base pair into the active site for phosphoryl transfer. NTP-driven translocation requires that NTP substrates enter the main-enzyme channel before loading into the active site. Based on this model, a new view of fidelity and efficiency of RNA synthesis is proposed. The model predicts that, during processive elongation, NTP-driven translocation is coupled to a protein conformational change that allows pyrophosphate release: coupling the end of one bond-addition cycle to substrate loading and translocation for the next. We present a detailed model of the RNA polymerase II elongation complex based on 2 low-affinity NTP binding sites located in the main-enzyme channel. This model posits that NTP substrates, elongation factors, and the conserved Rpb2 subunit fork loop 2 cooperate to regulate opening of the downstream transcription bubble.
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