title: Opposing classes of prp8 alleles modulate the transition between the catalytic steps of pre-mRNA splicing.
abstract: The spliceosome is thought to undergo a conformational change between the two catalytic steps of precursor messenger RNA splicing, although the specific events in this transition are poorly understood. We previously proposed a two-state model of splicing in which the conformations required for the first and second steps are in competition. Here, we identify and characterize a class of prp8 mutants that suppress first-step splicing defects and oppose the action of the previously described prp8 suppressors of second-step defects; these opposing effects parallel those of ribosomal 'ram' and 'restrictive' mutants, which alter fidelity of transfer RNA decoding. On the basis of genetic interactions, we propose that prp8-mediated substrate repositioning during the transition occurs between catalytic-center opening and closure mediated by the U6 small nuclear RNA and the DExH/D ATPase gene prp16. Modulation of these events alters splice-site selection and splicing fidelity.
authors.affiliation: The Rockefeller University, New York, New York 10021, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Charles C
authors.initials: CC
authors.lastname: Query
authors.forename: Maria M
authors.initials: MM
authors.lastname: Konarska
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000483:Alleles; D017931:DNA Primers / Q000235:genetics; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011487:Protein Conformation; D020365:RNA Helicases; D012326:RNA Splicing / Q000235:genetics / Q000502:physiology*; D000072260:RNA Splicing Factors; D012342:RNA, Small Nuclear / Q000235:genetics / Q000378:metabolism; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D017381:Spliceosomes / Q000235:genetics*
chemical_list: D017931:DNA Primers; C077018:PRP8 protein, S cerevisiae; D000072260:RNA Splicing Factors; D012342:RNA, Small Nuclear; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; C405486:U6 small nuclear RNA; D000251:Adenosine Triphosphatases; C075669:PRP16 protein, S cerevisiae; D020365:RNA Helicases