1. Department of Chemistry and Biochemistry, Gene Center, University of Munich, 81377 Munich, Germany

Correspondence to: Patrick Cramer¹ Email: cramer@lmb.uni-muenchen.de
Atomic coordinates and structure factors for the Pcf11 CID domain and the CTD–CID complex have been deposited in the Protein Data Bank under accession numbers 1SZ9 and 1SZA, respectively.

During transcription, RNA polymerase (Pol) II synthesizes eukaryotic messenger RNA. Transcription is coupled to RNA processing by the carboxy-terminal domain (CTD) of Pol II, which consists of up to 52 repeats of the sequence Tyr 1-Ser 2-Pro 3-Thr 4-Ser 5-Pro 6-Ser 7 (refs 1, 2). After phosphorylation, the CTD binds tightly to a conserved CTD-interacting domain (CID) present in the proteins Pcf11 and Nrd1, which are essential and evolutionarily conserved factors for polyadenylation-dependent and -independent 3'-RNA processing, respectively. Here we describe the structure of a Ser 2-phosphorylated CTD peptide bound to the CID domain of Pcf11. The CTD motif Ser 2-Pro 3-Thr 4-Ser 5 forms a -turn that binds to a conserved groove in the CID domain. The Ser 2 phosphate group does not make direct contact with the CID domain, but may be recognized indirectly because it stabilizes the -turn with an additional hydrogen bond. Iteration of the peptide structure results in a compact -spiral model of the CTD. The model suggests that, during the mRNA transcription-processing cycle, compact spiral regions in the CTD are unravelled and regenerated in a phosphorylation-dependent manner.

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.