Cotranscriptional spliceosome assembly occurs in a stepwise fashion and requires the cap binding complex.
Coupling between transcription and pre-mRNA splicing is a key regulatory mechanism in gene expression. Here, we investigate cotranscriptional spliceosome assembly in yeast, using in vivo crosslinking to determine the distribution of spliceosome components along intron-containing genes. Accumulation of the U1, U2, and U5 small nuclear ribonucleoprotein particles (snRNPs) and the 3' splice site binding factors Mud2p and BBP was detected in patterns indicative of progressive and complete spliceosome assembly; recruitment of the nineteen complex (NTC) component Prp19p suggests that splicing catalysis is also cotranscriptional. The separate dynamics of the U1, U2, and U5 snRNPs are consistent with stepwise recruitment of individual snRNPs rather than a preformed "penta-snRNP", as recently proposed. Finally, we show that the cap binding complex (CBC) is necessary, but not sufficient, for cotranscriptional spliceosome assembly. Thus, the demonstration of an essential link between CBC and spliceosome assembly in vivo indicates that 5' end capping couples pre-mRNA splicing to transcription.
Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
Janina
J
Görnemann
Kimberly M
KM
Kotovic
Katja
K
Hujer
Karla M
KM
Neugebauer
D001665:Binding Sites; D002384:Catalysis; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008868:Microtubule Proteins / Q000378:metabolism; D008954:Models, Biological; D039502:Nuclear Cap-Binding Protein Complex / Q000235:genetics / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D012326:RNA Splicing; D012261:Ribonucleoproteins / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000096:biosynthesis / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism* / Q000502:physiology; D000072668:Splicing Factor U2AF; D014158:Transcription, Genetic
C404863:BBP1 protein, S cerevisiae; D005656:Fungal Proteins; C089980:MUD2 protein, S cerevisiae; D008868:Microtubule Proteins; D039502:Nuclear Cap-Binding Protein Complex; D012322:RNA Precursors; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; D000072668:Splicing Factor U2AF