title: A cold-sensitive mRNA splicing mutant is a member of the RNA helicase gene family.
abstract: We have isolated a cold-sensitive mutant of Saccharomyces cerevisiae in which the first step of mRNA splicing is inhibited. The growth and splicing defects are recessive and cosegregate, thus defining a single essential gene (PRP28). The wild-type PRP28 gene was cloned, and sequence analysis reveals extensive homology to a family of proteins that are thought to function as ATP-dependent RNA helicases. The cold sensitivity is caused by a glycine-to-glutamic acid change in a conserved sequence motif. Interestingly, double mutants containing conditional alleles of PRP28 and PRP24, which encodes a U6 snRNA-binding protein, are inviable. In addition, a suppressor of prp28-1 is a mutant allele of PRP8, which encodes a U5 protein, thus linking PRP28 with U5. These data are consistent with a scenario in which PRP28 acts to unwind the U4/U6 base-pairing interaction in the U4/U6/U5 snRNP, facilitating the first covalent step of splicing.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
authors.forename: E J
authors.initials: EJ
authors.lastname: Strauss
authors.forename: C
authors.initials: C
authors.lastname: Guthrie
mesh_terms: D000595:Amino Acid Sequence; D003080:Cold Temperature; D003433:Crosses, Genetic; D005091:Exons; D005800:Genes, Fungal; D016153:Genes, Suppressor; D007700:Kinetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D015345:Oligonucleotide Probes; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000235:genetics*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D012689:Sequence Homology, Nucleic Acid
chemical_list: D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D012316:RNA Nucleotidyltransferases; D020365:RNA Helicases