Two-codon T-box riboswitch binding two tRNAs
Two-codon T-box riboswitch binding two tRNAs
复制标题
结合两个 tRNA 的双密码子 T 盒核糖开关
DOI：
--
复制
发表时间：
2013
影响因子：
11.1
通讯作者：
H. Becker
中科院分区：
文献类型：
--
作者：
Nizar Y. Saad;Vassiliki Stamatopoulou;Mélanie Brayé;D. Drainas;C. Stathopoulos;H. Becker
T盒核糖开关通过终止子或抗终止子结构的tRNA结合形成来控制下游基因的转录。以前报道的T盒被描述为单特异性核糖开关，可以通过密码子-反密码子相互作用与其指定环（SL）的核苷酸三联体结合特定的tRNA反密码子。然而，T盒可能表现出超越单个tRNA的特异性的可能性被忽视了。在丙酮丁醇梭菌中，调节必需的tRNA依赖性转酰胺基途径的操纵子的T盒含有具有tRNAAsn和tRNAGlu的两个潜在重叠密码子位置的SL。为了测试其特异性，我们进行了广泛的诱变，生化和化学探测分析。令人惊讶的是，这两种tRNA都可以在体外和体内有效地结合SL。通过SL上从一个重叠密码子到下一个重叠密码子的单个碱基移位，允许T盒的双重特异性。这个特征允许核糖开关感测两个tRNA并平衡两个氨基酸的生物合成。详细的基因组比较支持我们的观察结果，并表明，“灵活的”T盒核糖开关是广泛存在于细菌中，而且，它们的特异性是由代谢控制下的相互连接的途径。两者合计，我们的研究结果支持的概念，基因组依赖的密码子的SLs的歧义。此外，两个重叠密码子的存在在转录水平上施加了tRNA依赖性调节的独特实例。
T-box riboswitches control transcription of downstream genes through the tRNA-binding formation of terminator or antiterminator structures. Previously reported T-boxes were described as single-specificity riboswitches that can bind specific tRNA anticodons through codon–anticodon interactions with the nucleotide triplet of their specifier loop (SL). However, the possibility that T-boxes might exhibit specificity beyond a single tRNA had been overlooked. In Clostridium acetobutylicum, the T-box that regulates the operon for the essential tRNA-dependent transamidation pathway harbors a SL with two potential overlapping codon positions for tRNAAsn and tRNAGlu. To test its specificity, we performed extensive mutagenic, biochemical, and chemical probing analyses. Surprisingly, both tRNAs can efficiently bind the SL in vitro and in vivo. The dual specificity of the T-box is allowed by a single base shift on the SL from one overlapping codon to the next. This feature allows the riboswitch to sense two tRNAs and balance the biosynthesis of two amino acids. Detailed genomic comparisons support our observations and suggest that “flexible” T-box riboswitches are widespread among bacteria, and, moreover, their specificity is dictated by the metabolic interconnection of the pathways under control. Taken together, our results support the notion of a genome-dependent codon ambiguity of the SLs. Furthermore, the existence of two overlapping codons imposes a unique example of tRNA-dependent regulation at the transcriptional level.
DOI：
10.1016/j.bbagrm.2009.07.002
发表时间：
2009-09
影响因子：
4.7
作者：
Serganov, Alexander;Patel, Dinshaw J.
通讯作者：
Patel, Dinshaw J.
影响因子：
4.5
作者：
Nelson, Audrey R.;Henkin, Tina M.;Agris, Paul F.
通讯作者：
Agris, Paul F.
影响因子：
14.9
作者：
MILLIGAN, JF;GROEBE, DR;UHLENBECK, OC
通讯作者：
UHLENBECK, OC