Arabidopsis C-terminal domain phosphatase-like 1 and 2 are essential Ser-5-specific C-terminal domain phosphatases.
Transcription and mRNA processing are regulated by phosphorylation and dephosphorylation of the C-terminal domain (CTD) of RNA polymerase II, which consists of tandem repeats of a Y(1)S(2)P(3)T(4)S(5)P(6)S(7) heptapeptide. Previous studies showed that members of the plant CTD phosphatase-like (CPL) protein family differentially regulate osmotic stress-responsive and abscisic acid-responsive transcription in Arabidopsis thaliana. Here we report that AtCPL1 and AtCPL2 specifically dephosphorylate Ser-5 of the CTD heptad in Arabidopsis RNA polymerase II, but not Ser-2. An N-terminal catalytic domain of CPL1, which suffices for CTD Ser-5 phosphatase activity in vitro, includes a signature DXDXT acylphosphatase motif, but lacks a breast cancer 1 CTD, which is an essential component of the fungal and metazoan Fcp1 CTD phosphatase enzymes. The CTD of CPL1, which contains two putative double-stranded RNA binding motifs, is essential for the in vivo function of CPL1 and includes a C-terminal 23-aa signal responsible for its nuclear targeting. CPL2 has a similar domain structure but contains only one double-stranded RNA binding motif. Combining mutant alleles of CPL1 and CPL2 causes synthetic lethality of the male but not the female gametes. These results indicate that CPL1 and CPL2 exemplify a unique family of CTD Ser-5-specific phosphatases with an essential role in plant growth and development.
Koiwa
Hisashi
H
Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843-2133, USA. koiwa@neo-tamu.edu
Hausmann
Stéphane
S
Bang
Woo Young
WY
Ueda
Akihiro
A
Kondo
Naoko
N
Hiraguri
Akihiro
A
Fukuhara
Toshiyuki
T
Bahk
Jeong Dong
JD
Yun
Dae-Jin
DJ
Bressan
Ray A
RA
Hasegawa
Paul M
PM
Shuman
Stewart
S
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000201:enzymology; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000737:chemistry; D013379:Substrate Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D012694:Serine; D012319:RNA Polymerase II; C465438:CPL1 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases