期刊
EMBO REPORTS
卷 8, 期 11, 页码 1038-1043出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/sj.embor.7401079
关键词
transcription; Gre factors; RNA polymerase; crystal structure; binding site
资金
- NIGMS NIH HHS [R01 GM074840, GM74840, R01 GM067153, GM74252, R01 GM074252, GM67153] Funding Source: Medline
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.
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