Changes produced by bound tryptophan in the ribosome peptidyl transferase center in response to TnaC, a nascent leader peptide.
Changes produced by bound tryptophan in the ribosome peptidyl transferase center in response to TnaC, a nascent leader peptide.
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核糖体肽基转移酶中心的结合色氨酸响应 TnaC（一种新生前导肽）而产生变化。
DOI：
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发表时间：
2006
影响因子：
11.1
通讯作者：
C. Yanofsky
中科院分区：
文献类型：
--
作者：
L. R. Cruz;M. Gong;C. Yanofsky
体外研究已经证实，游离色氨酸通过与刚刚完成TnaC-tRNA（Pro）合成的核糖体结合来诱导tna操纵子表达，所述TnaC-tRNA（Pro）是该操纵子的前导肽的肽基-tRNA前体。色氨酸通过抑制释放因子2介导的这种肽基-tRNA在tnaC终止密码子处的切割而起作用。在这里，我们分析了游离色氨酸的核糖体位置，它在核糖体中产生的变化，以及新生TnaC-tRNA（Pro）肽在促进色氨酸结合和诱导中的作用。通过甲基化保护和结合/竞争分析检测诱导过程中发生的23 S rRNA核苷酸的位置变化。分析的核糖体-TnaC-tRNA（Pro）复合物在体外形成;它们含有野生型TnaC-tRNA（Pro）或其非功能性替代物TnaC（W12 R）-tRNA（Pro）。在比较这两种肽基-tRNA-核糖体复合物时，发现游离色氨酸阻断野生型核糖体-TnaC-tRNA（Pro）复合物的核苷酸A2572的甲基化，但不阻断核糖体-TnaC（W12 R）-tRNA（Pro）复合物的核苷酸A2572的甲基化。核苷酸A2572位于核糖体肽基转移酶中心。色氨酸是色氨酸的非诱导性竞争者，在阻断A2572甲基化方面无效;然而，它确实逆转了色氨酸的保护作用。游离色氨酸抑制嘌呤霉素切割TnaC-tRNA（Pro）;它也抑制抗生素稀疏霉素的结合。在TnaC（W12 R）-tRNA（Pro）突变体复合物中未观察到这些效应。这些发现证实，TnaC-tRNA（Pro）的Trp-12是在核糖体的肽基转移酶中心引入特异性变化所必需的，该变化激活游离色氨酸结合，导致肽基转移酶抑制。游离色氨酸似乎在肽基转移酶中心的几种抗生素的结合位点处或附近起作用。
Studies in vitro have established that free tryptophan induces tna operon expression by binding to the ribosome that has just completed synthesis of TnaC-tRNA(Pro), the peptidyl-tRNA precursor of the leader peptide of this operon. Tryptophan acts by inhibiting Release Factor 2-mediated cleavage of this peptidyl-tRNA at the tnaC stop codon. Here we analyze the ribosomal location of free tryptophan, the changes it produces in the ribosome, and the role of the nascent TnaC-tRNA(Pro) peptide in facilitating tryptophan binding and induction. The positional changes of 23S rRNA nucleotides that occur during induction were detected by using methylation protection and binding/competition assays. The ribosome-TnaC-tRNA(Pro) complexes analyzed were formed in vitro; they contained either wild-type TnaC-tRNA(Pro) or its nonfunctional substitute, TnaC(W12R)-tRNA(Pro). Upon comparing these two peptidyl-tRNA-ribosome complexes, free tryptophan was found to block methylation of nucleotide A2572 of wild-type ribosome-TnaC-tRNA(Pro) complexes but not of ribosome-TnaC(W12R)-tRNA(Pro) complexes. Nucleotide A2572 is in the ribosomal peptidyl transferase center. Tryptophanol, a noninducing competitor of tryptophan, was ineffective in blocking A2572 methylation; however, it did reverse the protective effect of tryptophan. Free tryptophan inhibited puromycin cleavage of TnaC-tRNA(Pro); it also inhibited binding of the antibiotic sparsomycin. These effects were not observed with TnaC(W12R)-tRNA(Pro) mutant complexes. These findings establish that Trp-12 of TnaC-tRNA(Pro) is required for introducing specific changes in the peptidyl transferase center of the ribosome that activate free tryptophan binding, resulting in peptidyl transferase inhibition. Free tryptophan appears to act at or near the binding sites of several antibiotics in the peptidyl transferase center.
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影响因子：
16
作者：
Cruz-Vera, LR;Rajagopal, S;Yanofsky, C
通讯作者：
Yanofsky, C
绘制核糖体中 tRNA 受体末端的 rRNA 邻域图。
DOI：
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发表时间：
1996
期刊：
The EMBO journal.
影响因子：
--
作者：
Joseph,S;Noller,HF
通讯作者：
Noller,HF
影响因子：
56.9
作者：
Ban, N;Nissen, P;Steitz, TA
通讯作者：
Steitz, TA
体内 tRNA 氨酰化水平的直接分析。
DOI：
--
发表时间：
1991
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Varshney,U;Lee,CP;RajBhandary,UL
通讯作者：
RajBhandary,UL