Hess S M, Stanford D R, Hopper A K
Cell and Molecular Biology Program, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Nucleic Acids Res. 1994 Apr 11;22(7):1265-71. doi: 10.1093/nar/22.7.1265.
The Saccharomyces cerevisiae genes, RRP1 and SRD1, are involved in processing rRNA precursor species to mature rRNAs. We reported previously that the rrp1-1 mutation caused temperature-sensitive lethality, hypersensitivity to aminoglycoside antibiotics, and defective processing of 27S pre-rRNA to 25S and 5.8S mature rRNAs. A second-site suppressor of the rrp1-1 mutation, srd1, corrects all three rrp1 mutant phenotypes. In order to learn more about the roles of the SRD1 and RRP1 genes in rRNA processing, we cloned and characterized the SRD1 gene. We identified an ORF, YCR18C, that complements srd1-2 suppression of rrp1-1. The DNA is physically located at the region of chromosome III where SRD1 has been genetically mapped. SRD1 encodes a putative 225 amino acid, 26 kDa protein containing a C2/C2 zinc finger motif that is also found in some transcription regulators and the eIF-2 beta translation initiating factors. The similarity of SRD1 to transcription regulators led us to test the model that srd1 mutations suppress rrp1 defects by altering the level of the RRP1 transcript. However, we found that SRD1 has no detectable effect on the steady state levels of RRP1 mRNA. We describe alternative models to explain the role of Srd1p in pre-rRNA processing.
酿酒酵母基因RRP1和SRD1参与将rRNA前体加工成成熟的rRNA。我们之前报道过，rrp1 - 1突变导致温度敏感型致死、对氨基糖苷类抗生素超敏，以及27S前体rRNA到25S和5.8S成熟rRNA的加工缺陷。rrp1 - 1突变的一个第二位点抑制子srd1能纠正rrp1突变体的所有三种表型。为了更多地了解SRD1和RRP1基因在rRNA加工中的作用，我们克隆并鉴定了SRD1基因。我们鉴定出一个开放阅读框YCR18C，它能互补srd1 - 2对rrp1 - 1的抑制作用。该DNA实际位于III号染色体上SRD1基因已被遗传定位的区域。SRD1编码一个推定的含225个氨基酸、26 kDa的蛋白质，该蛋白质含有一个C2/C2锌指基序，在一些转录调节因子和eIF - 2β翻译起始因子中也有发现。SRD1与转录调节因子的相似性使我们测试了这样一个模型，即srd1突变通过改变RRP1转录本的水平来抑制rrp1缺陷。然而，我们发现SRD1对RRP1 mRNA的稳态水平没有可检测到的影响。我们描述了其他模型来解释Srd1p在rRNA前体加工中的作用。
