科研之友
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摘要
We have isolated a class of mutants, aar2, showing the alpha mating type due to a defect in a1-alpha-2 repression but with alpha-2 repression activity from a nonmater strain of Saccharomyces cerevisiae expressing both a and alpha mating-type information in duplicate. Cells of the aar2 mutant and the aar2 disruptant also show a growth defect. A DNA fragment complementing the aar2 mutation contains an open reading frame consisting of 355 amino acid codons. Northern hybridization showed that cells of the aar2 mutant and disruptant contained alpha-1 and alpha-2 transcripts of the MAT-alpha gene (or HML-alpha in sir3 cells), but their a1 transcript of MATa (or HMRa in sir3 cells) migrated more slowly than that of the wild-type cells on gel electrophoresis and gave a diffused band. Primer extension analysis showed that the aar2 mutant and disruptant have a defect in splicing two short introns of the a1 pre-mRNA but not in splicing pre-mRNA of ACT1. The alpha mating type, but not the slow-growing phenotype, of the aar2 mutant was suppressed by introduction of an intronless MATa1 DNA. Thus, the AAR2 gene is involved in splicing pre-mRNA of the a1 cistron and other genes that are important for cell growth. The AAR2 locus was mapped on chromosome II beside the SSA3 locus, with a 276-bp space, but was not allelic to either PRP5 or PRP6, which are both located on chromosome II and function in splicing pre-mRNA of ACT1.
- 出版日期1991-11
