Ribosomal Decoding Processes at Codons in the A or P Sites Depend Differently on 2′-OH Groups (*)
Ribosomal Decoding Processes at Codons in the A or P Sites Depend Differently on 2′-OH Groups (*)
复制标题
A 或 P 位点密码子的核糖体解码过程不同地依赖于 2′-OH 基团 (*)
DOI：
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发表时间：
1995
影响因子：
4.8
通讯作者：
K. Nierhaus
中科院分区：
文献类型：
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作者：
Anatolij P. Potapov;F. Triana;K. Nierhaus
采用以下策略分析密码子的2′-OH基团对于关联tRNA与核糖体P和A位点结合的重要性。合成41个核苷酸的mRNA，其结构为C-GAA-UUC-GUC-C，在中间分别编码谷氨酸（E）、苯丙氨酸（F）和缬氨酸（V）（EFV-mRNA）。第二个模板，E（dF）V-mRNA，是相同的，除了它携带一个脱氧核糖密码子-dUdUdC-苯丙氨酸。tRNA与P位点的结合对P位点密码子的2′-OH基团的存在或不存在完全不敏感，如果A位点密码子缺少2′-OH基团，tRNA与P位点的结合也不受影响。然而，如果脱氧密码子存在于E位点，则结合受损。与此形成鲜明对比的是，在A位点和P位点存在脱氧密码子的情况下，Ac-氨酰-tRNA的A位点结合严重减少。结果表明，碱基配对的正确性也可以通过密码子的正确糖结构来“感知”，例如，在A位点的解码过程中（延伸），而不是在P位点的解码过程中（起始），糖皱褶（2′-OH）的定位。
The importance of 2′-OH groups of codons for binding of cognate tRNAs to ribosomal P and A sites was analyzed applying the following strategy. An mRNA of 41 nucleotides was synthesized with the structure C-GAA-UUC-GUC-C coding for glutamic acid (E), phenylalanine (F) and valine (V), respectively, in the middle (EFV-mRNA). A second template, the E(dF)V-mRNA, was identical except that it carried a deoxyribo-codon -dUdUdC- for phenylalanine. tRNA binding to the P site is totally insensitive to the presence or absence of the 2′-OH group of the P-site codon, and tRNA binding to the P site is also not affected if the A-site codon lacks the 2′-OH groups. However, binding is impaired if the deoxy-codon is present at the E site. In sharp contrast, the A-site binding of Ac-aminoacyl-tRNA was severely reduced in the presence of the deoxy-codon at the A site as well as at the P site. The results demonstrate that the correctness of base pairing is also “sensed” via a correct sugar structure of the codon, e.g. positioning of the sugar pucker (2′-OH), during the decoding process at the A site (elongation) but not during the decoding at the P site (initiation).