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Structure of fission yeast RNA polymerase II CTD phosphatase Fcp1-R271A bound to beryllium fluorideStructure of fission yeast RNA polymerase II CTD phosphatase Fcp1-R271A bound to beryllium fluoride
Structural highlights
FunctionFCP1_SCHPO Processively dephosphorylates 'Ser-2' and 'Ser-5' of the heptad repeats YSPTSPS in the C-terminal domain of the largest RNA polymerase II subunit. This promotes the activity of RNA polymerase II. Publication Abstract from PubMedProtein phosphatases regulate mRNA synthesis and processing by remodeling the carboxy-terminal domain (CTD) of RNA polymerase II (Pol2) to dynamically inscribe a Pol2 CTD code. Fission yeast Fcp1 (SpFcp1) is an essential 723-amino acid CTD phosphatase that preferentially hydrolyzes Ser2-PO4 of the YS2PTSPS repeat. The SpFcp1 catalytic domain (aa 140-580) is composed of a DxDxT acyl-phosphatase module (FCPH) and a BRCT module. Here we conducted a genetic analysis of SpFcp1, which shows that (i) phosphatase catalytic activity is required for vegetative growth of fission yeast; (ii) the flanking amino-terminal domain (aa 1-139) and its putative metal-binding motif C99H101Cys109C112 are essential; (iii) the carboxy-terminal domain (aa 581-723) is dispensable; (iv) a structurally disordered internal segment of the FCPH domain (aa 330-393) is dispensable; (v) lethal SpFcp1 mutations R271A and R299A are rescued by shortening the Pol2 CTD repeat array; and (vi) CTD Ser2-PO4 is not the only essential target of SpFcp1 in vivo. Recent studies highlight a second CTD code involving threonine phosphorylation of a repeat motif in transcription elongation factor Spt5. We find that Fcp1 can dephosphorylate Thr1-PO4 of the fission yeast Spt5 CTD nonamer repeat T1PAWNSGSK. We identify Arg271 as a governor of Pol2 versus Spt5 CTD substrate preference. Our findings implicate Fcp1 as a versatile sculptor of both the Pol2 and Spt5 CTD codes. Finally, we report a new 1.45 A crystal structure of SpFcp1 with Mg2+ and AlF3 that mimics an associative phosphorane transition state of the enzyme-aspartyl-phosphate hydrolysis reaction. Genetic and structural analysis of the essential fission yeast RNA polymerase II CTD phosphatase Fcp1.,Schwer B, Ghosh A, Sanchez AM, Lima CD, Shuman S RNA. 2015 Apr 16. PMID:25883047[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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