title: The carboxy-terminal coiled-coil of the RNA polymerase beta'-subunit is the main binding site for Gre factors.
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.
authors.affiliation: Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: Marina N
authors.initials: MN
authors.lastname: Vassylyeva
authors.forename: Vladimir
authors.initials: V
authors.lastname: Svetlov
authors.forename: Altaira D
authors.initials: AD
authors.lastname: Dearborn
authors.forename: Sergiy
authors.initials: S
authors.lastname: Klyuyev
authors.forename: Irina
authors.initials: I
authors.lastname: Artsimovitch
authors.forename: Dmitry G
authors.initials: DG
authors.lastname: Vassylyev
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D035602:Transcriptional Elongation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; C079667:GreB protein, E coli; D035602:Transcriptional Elongation Factors; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit