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The carboxy‐terminal coiled‐coil of the RNA polymerase β′‐subunit is the main binding site for Gre factors
Author(s) -
Vassylyeva Mari,
Svetlov Vladimir,
Dearborn Altaira D,
Klyuyev Sergiy,
Artsimovitch Irina,
Vassylyev Dmitry G
Publication year - 2007
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7401079
Subject(s) - rna polymerase , protein subunit , polymerase , binding site , biophysics , transcription (linguistics) , biology , coiled coil , cleavage (geology) , a site , microbiology and biotechnology , escherichia coli , chemistry , biochemistry , enzyme , gene , linguistics , philosophy , paleontology , fracture (geology)
Bacterial Gre transcript cleavage factors stimulate the intrinsic endonucleolytic activity of RNA polymerase (RNAP) to rescue stalled transcription complexes. They bind to RNAP and extend their coiled‐coil (CC) domains to the catalytic centre through the secondary channel. Three existing models for the Gre–RNAP complex postulate congruent mechanisms of Gre‐assisted catalysis, while offering conflicting views of the Gre–RNAP interactions. Here, we report the GreB structure of Escherichia coli . The GreB monomers form a triangle with the tip of the amino‐terminal CC of one molecule trapped within the hydrophobic cavity of the carboxy‐terminal domain of a second molecule. This arrangement suggests an analogous model for recruitment to RNAP. Indeed, the β′‐subunit CC located at the rim of the secondary channel has conserved hydrophobic residues at its tip. We show that substitutions of these residues and those in the GreB C‐terminal domain cavity confer defects in GreB activity and binding to RNAP, and present a plausible model for the RNAP–GreB complex.