Tedin K, Resch A, Bläsi U
Institute of Microbiology and Genetics, Vienna Biocenter, University of Vienna, Austria.
Mol Microbiol. 1997 Jul;25(1):189-99. doi: 10.1046/j.1365-2958.1997.4421810.x.
It has previously been proposed that Escherichia coli ribosomal protein S1 is required for the translation of highly structured mRNAs. In this study, we have examined the influence of structural features at or near the start codon of different mRNAs. The requirement for ribosomal protein S1 for translation initiation was determined when (i) the ribosome-binding site (RBS) was either preceded by a 5' non-translated leader sequence; (ii) the RBS was located 5' proximal to a mRNA start codon; and (iii) the start codon was the 5' terminal codon as exemplified by leaderless mRNAs. In vitro translation studies revealed that the leaderless lambda cl mRNA is translated with Bacillus stearothermophilusribosomes, naturally lacking a ribosomal protein S1 homologue, whereas ompA mRNA containing a 5' leader is not. These studies have been verified by toeprinting with E. coli ribosomes depleted for S1. We have shown that S1 is required for ternary complex formation on ompA mRNA but not for leaderless mRNAs or for mRNAs in which the RBS is close to the 5' end.
此前有人提出，大肠杆菌核糖体蛋白S1是翻译高度结构化mRNA所必需的。在本研究中，我们研究了不同mRNA起始密码子处或其附近结构特征的影响。当（i）核糖体结合位点（RBS）之前有一个5'非翻译前导序列时；（ii）RBS位于mRNA起始密码子的5'近端时；以及（iii）起始密码子是5'末端密码子，如无前导mRNA所示时，确定了翻译起始对核糖体蛋白S1的需求。体外翻译研究表明，无前导的λcl mRNA可被嗜热脂肪芽孢杆菌核糖体翻译，该核糖体天然缺乏核糖体蛋白S1同源物，而含有5'前导序列的ompA mRNA则不能。这些研究已通过用缺乏S1的大肠杆菌核糖体进行足迹法得到验证。我们已经表明，S1是ompA mRNA上三元复合物形成所必需的，但对于无前导mRNA或RBS靠近5'端的mRNA则不是必需的。
