Arabidopsis SCP1-like small phosphatases differentially dephosphorylate RNA polymerase II C-terminal domain.
RNA polymerase II carboxyl-terminal domain (pol II CTD) phosphatases that can dephosphorylate both Ser2-PO(4) and Ser5-PO(4) of CTD have been identified in animals and yeasts, however, only Ser5-PO(4)-specific CTD phosphatases have been identified in plants. Among predicted Arabidopsis SCP1-like small phosphatases (SSP), SSP4, SSP4b, and SSP5 form a unique group with long N-terminal extensions. While SSPs' expression showed similar tissue-specificities, SSP4 and SSP4b were localized exclusively in the nuclei, whereas SSP5 accumulated in both nuclei and cytoplasm. Detailed characterization of SSP activities using various peptides and full-length Arabidopsis pol II CTD substrates established that SSP4 and SSP4b could dephosphorylate both Ser2-PO(4) and Ser5-PO(4) of CTD, whereas SSP5 dephosphorylated only Ser5-PO(4). These results indicate that Arabidopsis SSP gene family encodes active CTD phosphatases like animal SCP1 family proteins, with distinct substrate specificities.
Department of Horticultural Sciences, Vegetable and Fruit Improvement Center, Molecular and Environmental Plant Sciences Program, MS2133 Texas A&M University, College Station, TX 77843-2133, USA.
Yue
Y
Feng
Jae Sook
JS
Kang
Sewon
S
Kim
Dae Jin
DJ
Yun
Sang Yeol
SY
Lee
Jeong Dong
JD
Bahk
Hisashi
H
Koiwa
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019295:Computational Biology; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D020033:Protein Isoforms; D012694:Serine; D012319:RNA Polymerase II; D010749:Phosphoprotein Phosphatases; C116022:carboxy-terminal domain phosphatase