Zhang, J, Palangat, M and Landick, R (2010) Role of the RNA polymerase trigger loop in catalysis and pausing. Nat. Struct. Mol. Biol. 17:99-104
The trigger loop (TL) is a polymorphous component of RNA polymerase (RNAP) that makes direct substrate contacts and promotes nucleotide addition when folded into an alpha-helical hairpin (trigger helices, TH). However, the roles of the TL/TH in transcript cleavage, catalysis, substrate selectivity and pausing remain ill defined. Based on in vitro assays of Escherichia coli RNAP bearing specific TL/TH alterations, we report that neither intrinsic nor regulator-assisted transcript cleavage of backtracked RNA requires formation of the TH. We find that the principal contribution of TH formation to rapid nucleotidyl transfer is steric alignment of the reactants rather than acid-base catalysis, and that the TL/TH cannot be the sole contributor to substrate selectivity. The similar effects of TL/TH substitutions on pausing and nucleotide addition provide additional support for the view that TH formation is rate-limiting for escape from nonbacktracked pauses.
Catalysis; DNA Primers/genetics; DNA-Directed RNA Polymerases/genetics; DNA-Directed RNA Polymerases/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Models, Molecular; Protein Structure, Secondary; Protein Subunits/genetics; Protein Subunits/metabolism; Substrate Specificity; Transcription, Genetic/genetics; Transcription, Genetic/physiology
You can help EcoliWiki by summarizing why this paper is useful
Useful Materials and Methods
You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.
|Gene product||Qualifier||GO ID||GO term name||Evidence Code||with/from||Aspect||Notes||Status|
Add links to pages that link here (e.g. gene, product, method pages)
See Help:References for how to manage references in EcoliWiki.