Trigger loop dynamics mediate the balance between the transcriptional fidelity and speed of RNA polymerase II.

ABSTRACT: During transcription, RNA polymerase II (RNAPII) must select the correct nucleotide, catalyze its addition to the growing RNA transcript, and move stepwise along the DNA until a gene is fully transcribed. In all kingdoms of life, transcription must be finely tuned to ensure an appropriate balance between fidelity and speed. Here, we used an optical-trapping assay with high spatiotemporal resolution to probe directly the motion of individual RNAPII molecules as they pass through each of the enzymatic steps of transcript elongation. We report direct evidence that the RNAPII trigger loop, an evolutionarily conserved protein subdomain, serves as a master regulator of transcription, affecting each of the three main phases of elongation, namely: substrate selection, translocation, and catalysis.

SUBMITTER: Larson MH 

PROVIDER: S-EPMC3340090 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature