Translocation and fidelity of Escherichia coli RNA polymerase.

ABSTRACT: Exonuclease (exo) III was used as a probe of the Escherichia coli RNA polymerase (RNAP) ternary elongation complex (TEC) downstream border. In the absence of NTPs, RNAP appears to stall primarily in a post-translocated state and to return slowly to a pre-translocated state. Exo III mapping, therefore, appears inconsistent with an unrestrained thermal ratchet model for translocation, in which RNAP freely and rapidly oscillates between pre- and post-translocated positions. The forward translocation state is made more stable by lowering the pH and/or by elevating the salt concentration, indicating a probable role of protonated histidine(s) in regulating accurate NTP loading and translocation. Because the post-translocated TEC can be strongly stabilized by NTP addition, NTP analogs were ranked

SUBMITTER: Nedialkov YA 

PROVIDER: S-EPMC4042587 | biostudies-literature | 2013 May-Jun

REPOSITORIES: biostudies-literature