Features of ribosome-peptidyl-tRNA interactions essential for tryptophan induction of tna operon expression
Features of ribosome-peptidyl-tRNA interactions essential for tryptophan induction of tna operon expression
复制标题
DOI：
10.1016/j.molcel.2005.06.013
复制
发表时间：
2005-08-05
期刊：
影响因子：
16
通讯作者：
Yanofsky, C
中科院分区：
文献类型：
--
作者：
Cruz-Vera, LR;Rajagopal, S;Yanofsky, C
某些新生肽序列，当在核糖体出口通道内时，可以抑制翻译终止和/或肽延伸。大肠杆菌tna操纵子的24个残基的前导肽基-tRNA，TnaC-tRNA（Pro），在过量色氨酸存在下，抵抗在tnaC终止密码子处的切割。TnaC残基Trp 12对这种抑制作用至关重要。Trp 12在出口通道中的大致位置通过将TnaC-tRNA（Pro）的Lys 11与23 S rRNA的核苷酸A750交联来确定。Trp 12在TnaC-tRNA（Pro）中的存在降低了23 S rRNA的核苷酸A788的甲基化，这意味着A788置换。在751位插入腺苷酸，或在23 S rRNA中引入改变U2609 C或在核糖体蛋白L22中引入改变K90 H或K90 W，实际上消除了色氨酸诱导。这些修饰和突变的区域大多位于TnaC-tRNA（Pro）的Trp 12所占据的推定位点附近。这些发现确定了tna操纵子诱导所必需的核糖体出口通道的特征。
Certain nascent peptide sequences, when within the ribosomal exit tunnel, can inhibit translation termination and/or peptide elongation. The 24 residue leader peptidyl-tRNA of the tna operon of E coli, TnaC-tRNA(Pro), in the presence of excess tryptophan, resists cleavage at the tnaC stop codon. TnaC residue Trp12 is crucial for this inhibition. The approximate location of Trp12 in the exit tunnel was determined by crosslinking Lys11 of TnaC-tRNA(Pro) to nucleotide A750 of 23S rRNA. Methylation of nucleotide A788 of 23S rRNA was reduced by the presence of Trp12 in TnaC-tRNA(Pro), implying A788 displacement. Inserting an adenylate at position 751, or introducing the change U2609C in 23S rRNA or the change K90H or K90W in ribosomal protein L22, virtually eliminated tryptophan induction. These modified and mutated regions are mostly located near the putative site occupied by Trp12 of TnaC-tRNA(Pro). These findings identify features of the ribosomal exit tunnel essential for tna operon induction.