title: The Prp19p-associated complex in spliceosome activation.
abstract: During spliceosome activation, a large structural rearrangement occurs that involves the release of two small nuclear RNAs, U1 and U4, and the addition of a protein complex associated with Prp19p. We show here that the Prp19p-associated complex is required for stable association of U5 and U6 with the spliceosome after U4 is dissociated. Ultraviolet crosslinking analysis revealed the existence of two modes of base pairing between U6 and the 5' splice site, as well as a switch of such base pairing from one to the other that required the Prp19p-associated complex during spliceosome activation. Moreover, a Prp19p-dependent structural change in U6 small nuclear ribonucleoprotein particles was detected that involves destabilization of Sm-like (Lsm) proteins to bring about interactions between the Lsm binding site of U6 and the intron sequence near the 5' splice site, indicating dynamic association of Lsm with U6 and a direct role of Lsm proteins in activation of the spliceosome.
authors.affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Shih-Pai, Taiwan, Republic of China.
authors.forename: Shih-Peng
authors.initials: SP
authors.lastname: Chan
authors.forename: Der-I
authors.initials: DI
authors.lastname: Kao
authors.forename: Wei-Yü
authors.initials: WY
authors.lastname: Tsai
authors.forename: Soo-Chen
authors.initials: SC
authors.lastname: Cheng
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D020029:Base Pairing; D001665:Binding Sites; D015152:Blotting, Northern; D007438:Introns; D008969:Molecular Sequence Data; D012322:RNA Precursors / Q000378:metabolism; D012326:RNA Splicing; D000072260:RNA Splicing Factors; D012342:RNA, Small Nuclear / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D016914:Ribonuclease H / Q000378:metabolism; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000737:chemistry / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017381:Spliceosomes / Q000378:metabolism*
chemical_list: C079877:PRP19 protein, S cerevisiae; D012322:RNA Precursors; D000072260:RNA Splicing Factors; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; C405483:U1 small nuclear RNA; C405482:U4 small nuclear RNA; C405485:U5 small nuclear RNA; D000255:Adenosine Triphosphate; D016914:Ribonuclease H