Splicing factor Cwc22 is required for the function of Prp2 and for the spliceosome to escape from a futile pathway.
Cwc22 was previously identified to associate with the pre-mRNA splicing factor Cef1/Ntc85, a component of the Prp19-associated complex (nineteen complex [NTC]) involved in spliceosome activation. We show here that Cwc22 is required for pre-mRNA splicing both in vivo and in vitro but is neither tightly associated with the NTC nor required for spliceosome activation. Cwc22 is associated with the spliceosome prior to catalytic steps and remains associated throughout the reaction. The stable association of Cwc22 with the spliceosome requires the presence of the NTC but is independent of Prp2. Although Cwc22 is not required for the recruitment of Prp2 to the spliceosome, it is essential for the function of Prp2 in promoting the release of the U2 components SF3a and SF3b. In the absence of Cwc22, Prp2 can bind to the spliceosome but is dissociated upon ATP hydrolysis without promoting the release of SF3a/b. Thus, Cwc22 represents a novel ATP-dependent step one factor besides Prp2 and Spp2 and has a distinct role from that of Spp2 in mediating the function of Prp2.
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 115, Republic of China.
Tzu-Chi
TC
Yeh
Hseuh-Lien
HL
Liu
Che-Sheng
CS
Chung
Nan-Ying
NY
Wu
Yen-Chi
YC
Liu
Soo-Chen
SC
Cheng
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D017124:Conserved Sequence; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D004271:DNA, Fungal / Q000235:genetics; D005800:Genes, Fungal; D008954:Models, Biological; D008969:Molecular Sequence Data; D012326:RNA Splicing; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D017381:Spliceosomes / Q000378:metabolism*
C513239:CEF1 protein, S cerevisiae; C555352:CWC22 protein, S cerevisiae; D004271:DNA, Fungal; C079877:PRP19 protein, S cerevisiae; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C507652:Spp382 protein, S cerevisiae; D000255:Adenosine Triphosphate; C066490:PRP2 protein, S cerevisiae; D053487:DEAD-box RNA Helicases