1. The carboxy-terminal coiled-coil of the RNA polymerase beta'-subunit is the main binding site for Gre factors.
- Author
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Vassylyeva MN, Svetlov V, Dearborn AD, Klyuyev S, Artsimovitch I, and Vassylyev DG
- Subjects
- Amino Acid Sequence, Binding Sites, DNA-Directed RNA Polymerases genetics, DNA-Directed RNA Polymerases metabolism, Escherichia coli metabolism, Escherichia coli Proteins chemistry, Escherichia coli Proteins genetics, Gene Expression Regulation, Bacterial, Models, Molecular, Molecular Sequence Data, Sequence Alignment, Transcriptional Elongation Factors chemistry, Transcriptional Elongation Factors genetics, DNA-Directed RNA Polymerases chemistry, Escherichia coli Proteins metabolism, Protein Structure, Secondary, Transcriptional Elongation Factors metabolism
- Abstract
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 beta'-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.
- Published
- 2007
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