Gene RRN4 in Saccharomyces cerevisiae encodes the A12.2 subunit of RNA polymerase I and is essential only at high temperatures.
Gene RRN4 in Saccharomyces cerevisiae encodes the A12.2 subunit of RNA polymerase I and is essential only at high temperatures.
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酿酒酵母中的基因 RRN4 编码 RNA 聚合酶 I 的 A12.2 亚基，并且仅在高温下才是必需的。
DOI：
10.1128/mcb.13.1.114-122.1993
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发表时间：
1993
影响因子：
5.3
通讯作者：
Nomura,M
中科院分区：
文献类型：
--
作者：
Nogi,Y;Yano,R;Dodd,J;Carles,C;Nomura,M
我们之前已经分离出酿酒酵母的突变体，这些突变体主要在RNA聚合酶I转录35S rRNA基因时存在缺陷，并且已经鉴定出参与这一过程的基因（RRN1toRRN9）。我们现在已经克隆了therrn4-1突变体的温度敏感表型，并确定了其完整的核苷酸序列。以下结果表明，therrn4基因编码RNA聚合酶i的A12.2亚基。首先，在埃希氏菌中表达的RRN4蛋白与A12.2特异性抗血清共反应。其次，测定了从A12.2中获得的三个色氨酸肽的氨基酸序列，这些序列与推导出的rn4蛋白的氨基酸序列一致。therrn4蛋白（A12.2）的氨基酸序列与酵母RNA聚合酶II的RPB9 （B12.6）亚基相似；相似性包括两个假定的锌结合结构域的存在。因此，A12.2是B12.6的同源物。我们建议将theRRN4geneRPA12重新命名。rpa12的缺失会产生对生长热而不冷敏感的细胞。我们发现，在允许的温度下生长的这种零突变体中，RNA聚合酶I的最大亚基A190的细胞浓度低于野生型。此外，多拷贝质粒上的rpa190 （A190基因）可以部分抑制therpa12null突变体的温度敏感表型。这些结果表明，A12.2在A190组装成稳定的聚合酶I结构中发挥了作用。
We have previously isolated mutants ofSaccharomyces cerevisiaethat are primarily defective in transcription of 35S rRNA genes by RNA polymerase I and have identified genes (RRN1toRRN9) involved in this process. We have now cloned theRRN4gene by complementation of the temperature-sensitive phenotype of therrn4-1mutant and have determined its complete nucleotide sequence. The following results demonstrate that theRRN4gene encodes the A12.2 subunit of RNA polymerase I. First, RRN4 protein expressed inEscherichia colireacted with a specific antiserum against A12.2. Second, amino acid sequences of three tryptic peptides obtained from A12.2 were determined, and these sequences are found in the deduced amino acid sequence of the RRN4 protein. The amino acid sequence of theRRN4protein (A12.2) is similar to that of the RPB9 (B12.6) subunit of yeast RNA polymerase II; the similarity includes the presence of two putative zinc-binding domains. Thus, A12.2 is a homolog of B12.6. We propose to rename theRRN4geneRPA12. Deletion ofRPA12produces cells that are heat but not cold sensitive for growth. We have found that in such null mutants growing at permissive temperatures, the cellular concentration of A190, the largest subunit of RNA polymerase I, is lower than in the wild type. In addition, the temperature-sensitive phenotype of therpa12null mutants can be partially suppressed byRPA190(the gene for A190) on multicopy plasmids. These results suggest that A12.2 plays a role in the assembly of A190 into a stable polymerase I structure.