3p9y

Publication Abstract from PubMed

RNA polymerase II coordinates co-transcriptional events by recruiting distinct sets of nuclear factors to specific stages of transcription via changes of phosphorylation patterns along its C-terminal domain (CTD). Although it has become increasingly clear that proline isomerization also helps regulate CTD-associated processes, the molecular basis of its role is unknown. Here, we report the structure of the Ser(P)(5) CTD phosphatase Ssu72 in complex with substrate, revealing a remarkable CTD conformation with the Ser(P)(5)-Pro(6) motif in the cis configuration. We show that the cis-Ser(P)(5)-Pro(6) isomer is the minor population in solution and that Ess1-catalyzed cis-trans-proline isomerization facilitates rapid dephosphorylation by Ssu72, providing an explanation for recently discovered in vivo connections between these enzymes and a revised model for CTD-mediated small nuclear RNA termination. This work presents the first structural evidence of a cis-proline-specific enzyme and an unexpected mechanism of isomer-based regulation of phosphorylation, with broad implications for CTD biology.

cis-Proline-mediated Ser(P)5 Dephosphorylation by the RNA Polymerase II C-terminal Domain Phosphatase Ssu72.,Werner-Allen JW, Lee CJ, Liu P, Nicely NI, Wang S, Greenleaf AL, Zhou P J Biol Chem. 2011 Feb 18;286(7):5717-26. Epub 2010 Dec 15. PMID:21159777^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.