Trigger loop of RNA polymerase is a positional, not acid-base, catalyst for both transcription and proofreading.

ABSTRACT: The active site of multisubunit RNA polymerases (RNAPs) is highly conserved from humans to bacteria. This single site catalyzes both nucleotide addition required for RNA transcript synthesis and excision of incorrect nucleotides after misincorporation as a proofreading mechanism. Phosphoryl transfer and proofreading hydrolysis are controlled in part by a dynamic RNAP component called the trigger loop (TL), which cycles between an unfolded loop and an α-helical hairpin [trigger helices (TH)] required for rapid nucleotide addition. The precise roles of the TL/TH in RNA synthesis and hydrolysis remain unclear. An invariant histidine residue has been proposed to function in the TH form as a general acid in RNA synthesis and as a general base in RNA hydrolysis. The effects of conservative, noni

SUBMITTER: Mishanina TV 

PROVIDER: S-EPMC5495254 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature