Kawakami K, Jönsson Y H, Björk G R, Ikeda H, Nakamura Y
Department of Tumor Biology, University of Tokyo, Japan.
Proc Natl Acad Sci U S A. 1988 Aug;85(15):5620-4. doi: 10.1073/pnas.85.15.5620.
The prfB gene encodes peptide-chain-release factor 2 of Escherichia coli, which catalyzes translation termination at UGA and UAA codons. The gene, identified by sequencing, is located at the 62-min region of the E. coli chromosome. The prfB gene is followed by an open reading frame encoding a 57,603-Da protein. This downstream open reading frame was identified as herC, a gene defined by a suppressor mutation that restores replication of a ColE1 plasmid mutant. RNA blot hybridization and S1 nuclease protection analyses of in vivo transcripts showed that prfB and herC are cotranscribed into a 2800-base transcript in the counterclockwise direction with respect to the E. coli genetic map. Thus, we refer to the two genes as the prfB-herC operon. Data are presented that suggest that supK, a mutation in Salmonella typhimurium that suppresses UGA termination, is the structural gene for Salmonella release factor 2. Translation control within the prfB-herC operon and the relationship of these genes to a tRNA methyltransferase are discussed.
prfB基因编码大肠杆菌的肽链释放因子2，其催化UGA和UAA密码子处的翻译终止。该基因通过测序鉴定，位于大肠杆菌染色体的62分钟区域。prfB基因后面是一个编码57603道尔顿蛋白质的开放阅读框。这个下游开放阅读框被鉴定为herC，一个由抑制突变定义的基因，该突变可恢复ColE1质粒突变体的复制。对体内转录本的RNA印迹杂交和S1核酸酶保护分析表明，相对于大肠杆菌遗传图谱，prfB和herC以逆时针方向共转录成一个2800个碱基的转录本。因此，我们将这两个基因称为prfB-herC操纵子。文中给出的数据表明，鼠伤寒沙门氏菌中抑制UGA终止的supK突变是沙门氏菌释放因子2的结构基因。本文讨论了prfB-herC操纵子内的翻译控制以及这些基因与一种tRNA甲基转移酶的关系。
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