Ssu72 Is an RNA polymerase II CTD phosphatase.
Phosphorylation of serine-2 (S2) and serine-5 (S5) of the C-terminal domain (CTD) of RNA polymerase II (RNAP II) is a dynamic process that regulates the transcription cycle and coordinates recruitment of RNA processing factors. The Fcp1 CTD phosphatase catalyzes dephosphorylation of S2-P. Here, we report that Ssu72, a component of the yeast cleavage/polyadenylation factor (CPF) complex, is a CTD phosphatase with specificity for S5-P. Ssu72 catalyzes CTD S5-P dephosphorylation in association with the Pta1 component of the CPF complex, although its essential role in 3' end processing is independent of catalytic activity. Depletion of Ssu72 impairs transcription in vitro, and this defect can be rescued by recombinant, catalytically active Ssu72. We propose that Ssu72 has a dual role in transcription, one as a CTD S5-P phosphatase that regenerates the initiation-competent, hypophosphorylated form of RNAP II and the other as a factor necessary for cleavage of pre-mRNA and efficient transcription termination.
Krishnamurthy
Shankarling
S
Department of Biochemistry, Division of Nucleic Acids Enzymology, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
He
Xiaoyuan
X
Reyes-Reyes
Mariela
M
Moore
Claire
C
Hampsey
Michael
M
D002352:Carrier Proteins / Q000378:metabolism*; D005809:Genes, Regulator / Q000235:genetics; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D012319:RNA Polymerase II / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity; D014158:Transcription, Genetic / Q000235:genetics*; D039221:mRNA Cleavage and Polyadenylation Factors / Q000378:metabolism
D002352:Carrier Proteins; C076229:PTA1 protein, S cerevisiae; D012333:RNA, Messenger; C416934:SSU72 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D039221:mRNA Cleavage and Polyadenylation Factors; D012694:Serine; D012319:RNA Polymerase II; D010749:Phosphoprotein Phosphatases; C116022:carboxy-terminal domain phosphatase