A mutation in a methionine tRNA gene suppresses the prp2-1 Ts mutation and causes a pre-mRNA splicing defect in Saccharomyces cerevisiae.
The PRP2 gene in Saccharomyces cerevisiae encodes an RNA-dependent ATPase that activates spliceosomes for the first transesterification reaction in pre-mRNA splicing. We have identified a mutation in the elongation methionine tRNA gene EMT1 as a dominant, allele-specific suppressor of the temperature-sensitive prp2-1 mutation. The EMT1-201 mutant suppressed prp2-1 by relieving the splicing block at high temperature. Furthermore, EMT1-201 single mutant cells displayed pre-mRNA splicing and cold-sensitive growth defects at 18 degrees. The mutation in EMT1-201 is located in the anticodon, changing CAT to CAG, which presumably allowed EMT1-201 suppressor tRNA to recognize CUG leucine codons instead of AUG methionine codons. Interestingly, the prp2-1 allele contains a point mutation that changes glycine to aspartate, indicating that EMT1-201 does not act by classical missense suppression. Extra copies of the tRNA(Leu)(UAG) gene rescued the cold sensitivity and in vitro splicing defect of EMT1-201. This study provides the first example in which a mutation in a tRNA gene confers a pre-mRNA processing (prp) phenotype.
Kim
D H
DH
Department of Molecular Biology, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA.
Edwalds-Gilbert
G
G
Ren
C
C
Lin
R J
RJ
D019943:Amino Acid Substitution; D000926:Anticodon / Q000235:genetics; D053487:DEAD-box RNA Helicases; D005091:Exons; D005656:Fungal Proteins / Q000235:genetics*; D016153:Genes, Suppressor; D005816:Genetic Complementation Test; D005838:Genotype; D007438:Introns; D017354:Point Mutation; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*; D012358:RNA, Transfer, Met / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic
D000926:Anticodon; D005656:Fungal Proteins; D012322:RNA Precursors; D012331:RNA, Fungal; D012333:RNA, Messenger; D012358:RNA, Transfer, Met; D029701:Saccharomyces cerevisiae Proteins; C066490:PRP2 protein, S cerevisiae; D053487:DEAD-box RNA Helicases