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.
Feng
Yue
Y
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.
Kang
Jae Sook
JS
Kim
Sewon
S
Yun
Dae Jin
DJ
Lee
Sang Yeol
SY
Bahk
Jeong Dong
JD
Koiwa
Hisashi
H
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