Paluh J L, Clayton D A
Department of Developmental Biology, Stanford University School of Medicine, CA 94305-5427, USA.
EMBO J. 1996 Sep 2;15(17):4723-33.
The essential gene for RNase MRP RNA, mrp1, was identified previously in Schizosaccharomyces pombe by homology to mammalian RNase MRP RNAs. Here we describe distinct site-specific mutations in RNase MRP RNA that support a conserved role for this ribonucleoprotein in nucleolar 5.8S rRNA processing. One characterized mutation, mrp1-ND90, displays dominance and results in accumulation of unspliced precursor RNAs of dimeric tRNA(Ser)-tRNA(Met)i, suggesting a novel nuclear role for RNase MRP in tRNA processing. Cells carrying the mrp1-ND90 mutation, in the absence of a wild-type copy of mrp1, additionally require the mitochondrially associated nuclear mutation ptp1-1 for viability. Analysis of this mrp1 mutation reinforces previous biochemical evidence suggesting a role for RNase MRP in mitochondrial DNA replication. Several mutations in mrp1 result in unusual cellular morphology, including alterated nuclear organization, and are consistent with a broader nuclear role for RNase MRP in regulating a nuclear signal for septation; these results are a further indication of the multifunctional nature of this ribonucleoprotein.
核糖核酸酶MRP RNA的必需基因mrp1，先前在粟酒裂殖酵母中通过与哺乳动物核糖核酸酶MRP RNA的同源性得以鉴定。在此，我们描述了核糖核酸酶MRP RNA中不同的位点特异性突变，这些突变支持了这种核糖核蛋白在核仁5.8S rRNA加工过程中的保守作用。一个已表征的突变体mrp1-ND90表现出显性，并导致二聚体tRNA(Ser)-tRNA(Met)i的未剪接前体RNA积累，这表明核糖核酸酶MRP在tRNA加工过程中具有一种新的核功能。携带mrp1-ND90突变的细胞，在没有mrp1野生型拷贝的情况下，还需要线粒体相关的核突变ptp1-1才能存活。对这种mrp1突变的分析强化了先前的生化证据，表明核糖核酸酶MRP在线粒体DNA复制中发挥作用。mrp1中的几个突变导致异常的细胞形态，包括核组织改变，这与核糖核酸酶MRP在调节细胞分裂的核信号方面具有更广泛的核功能一致；这些结果进一步表明了这种核糖核蛋白的多功能性质。
