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The highly conserved glutamic acid 791 of Rpb2 is involved in the binding of NTP and Mg(B) in the active center of human RNA polymerase II.

Nucleic Acids Res.2005 May 10;33(8):2629-39
Marie-France Langelier 1 , Dania Baali , Vincent Trinh , Jack Greenblatt , Jacques Archambault , Benoit Coulombe
Marie-France Langelier 1 , Dania Baali , Vincent Trinh , Jack Greenblatt , Jacques Archambault , Benoit Coulombe
+ et al

[No authors listed]

Author information
  • 1 Laboratory of Gene Transcription, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, Québec, Canada H2W 1R7.
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摘要


During transcription by RNA polymerase (RNAP) II, the incoming ribonucleoside triphosphate (NTP) enters the catalytic center in association with an Mg2+ ion, termed metal B [Mg(B)]. When bound to RNAP II, Mg(B) is coordinated by the beta and gamma phosphates of the NTP, Rpb1 residues D481 and D483 and Rpb2 residue D837. Rpb2 residue D837 is highly conserved across species. Notably, its neighboring residue, E836 (E791 in human RNAP II), is also highly conserved. To probe the role of E791 in transcription, we have affinity purified and characterized a human RNAP II mutant in which this residue was substituted for alanine. Our results indicate that the transcription activity of the Rpb2 E791A mutant is impaired at low NTP concentrations both in vitro and in vivo. They also revealed that both its NTP polymerization and transcript cleavage activities are decreased at low Mg concentrations. Because Rpb2 residue E791 appears to be located too far from the NTP-Mg(B) complex to make direct contact at either the entry (E) or addition (A) site, we propose alternative mechanisms by which this highly conserved residue participates in loading NTP-Mg(B) in the active site during transcription.

基因