4h3k
From Proteopedia
Crystal structure of a ternary complex of human symplekin NTD, human Ssu72 and a RNA polymerase II CTD peptide phosphorylated at Ser-2, Ser-5 and Ser-7
Structural highlights
Function[SYMPK_HUMAN] Scaffold protein that functions as a component of a multimolecular complex involved in histone mRNA 3'-end processing. Specific component of the tight junction (TJ) plaque, but might not be an exclusively junctional component. May have a house-keeping rule. Is involved in pre-mRNA polyadenylation. Enhances SSU72 phosphatase activity.[1] [2] [SSU72_HUMAN] Protein phosphatase that catalyzes the dephosphorylation of the C-terminal domain of RNA polymerase II. Plays a role in RNA processing and termination. Plays a role in pre-mRNA polyadenylation via its interaction with SYMPK.[3] [4] [5] Publication Abstract from PubMedSsu72, an RNA polymerase II C-terminal domain (CTD) phospho-Ser5 (pSer5) phosphatase, was recently reported to have pSer7 phosphatase activity as well. We report here the crystal structure of a ternary complex of the N-terminal domain of human symplekin, human Ssu72, and a 10-mer pSer7 CTD peptide. Surprisingly, the peptide is bound in the Ssu72 active site with its backbone running in the opposite direction compared with a pSer5 peptide. The pSer7 phosphatase activity of Ssu72 is approximately 4000-fold lower than its pSer5 phosphatase activity toward a peptide substrate, consistent with the structural observations. An unexpected binding mode for a Pol II CTD peptide phosphorylated at Ser7 in the active site of the CTD phosphatase Ssu72.,Xiang K, Manley JL, Tong L Genes Dev. 2012 Oct 15;26(20):2265-70. doi: 10.1101/gad.198853.112. PMID:23070812[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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