title: Pin1 modulates the dephosphorylation of the RNA polymerase II C-terminal domain by yeast Fcp1.
abstract: The reversible phosphorylation of serine and threonine residues N-terminal to proline (pSer/Thr-Pro) is an important signaling mechanism in the cell. The pSer/Thr-Pro moiety exists in the two distinct cis and trans conformations, whose conversion is catalyzed by the peptidyl-prolyl isomerase (PPIase) Pin1. Among others, Pin1 binds to the phosphorylated C-terminal domain (CTD) of the largest subunit of the RNA polymerase II, but the biochemical and functional relevance of this interaction is unknown. Here we confirm that the CTD phosphatase Fcp1 can suppress a Pin1 mutation in yeast. Furthermore, this genetic interaction requires the phosphatase domain as well as the BRCT domain of Fcp1, suggesting a critical role of the Fcp1 localization. Based on these observations, we developed a new in vitro assay to analyze the CTD dephosphorylation by Fcp1 that uses only recombinant proteins and mimics the in vivo situation. This assay allows us to present strong evidence that Pin1 is able to stimulate CTD dephosphorylation by Fcp1 in vitro, and that this stimulation depends on Pin1's PPIase activity. Finally, Pin1 significantly increased the dephosphorylation of the CTD on the Ser(5)-Pro motif, but not on Ser(2)-Pro in yeast, which can be explained with Pin1's substrate specificity. Together, our results indicate a new role for Pin1 in the regulation of CTD phosphorylation and present a further example for prolyl isomerization-dependent protein dephosphorylation.
authors.affiliation: Cancer Biology Program, Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, HIM 1047, 330 Brookline Avenue, Boston, MA 02215, USA.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kops
authors.forename: Xiao Zhen
authors.initials: XZ
authors.lastname: Zhou
authors.forename: Kun Ping
authors.initials: KP
authors.lastname: Lu
mesh_terms: D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D029701:Saccharomyces cerevisiae Proteins; D012319:RNA Polymerase II; D010749:Phosphoprotein Phosphatases; C116022:carboxy-terminal domain phosphatase; C000606845:ESS1 protein, S cerevisiae; D019696:Peptidylprolyl Isomerase