Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005-1892, United States.
FEBS Lett. 2013 Nov 1;587(21):3495-9. doi: 10.1016/j.febslet.2013.09.003. Epub 2013 Sep 11.
In Gram-positive bacteria the tRNA-dependent T box riboswitch regulates the expression of many amino acid biosynthetic and aminoacyl-tRNA synthetase genes through a transcription attenuation mechanism. The Specifier domain of the T box riboswitch contains the Specifier sequence that is complementary to the tRNA anticodon and is flanked by a highly conserved purine nucleotide that could result in a fourth base pair involving the invariant U33 of tRNA. We show that the interaction between the T box Specifier domain and tRNA consists of three Watson-Crick base pairs and that U33 confers stability to the complex through intramolecular hydrogen bonding. Enhanced packing within the Specifier domain loop E motif may stabilize the complex and contribute to cognate tRNA selection.
在革兰氏阳性菌中,tRNA 依赖性 T 盒核糖体开关通过转录衰减机制调节许多氨基酸生物合成和氨酰-tRNA 合成酶基因的表达。T 盒核糖体开关的 Specifier 结构域包含与 tRNA 反密码子互补的 Specifier 序列,其两侧是高度保守的嘌呤核苷酸,可能导致涉及 tRNA 不变的 U33 的第四个碱基对。我们表明,T 盒 Specifier 结构域与 tRNA 的相互作用由三个 Watson-Crick 碱基对组成,并且 U33 通过分子内氢键赋予复合物稳定性。Specifier 结构域环 E 基序内的增强包装可能稳定复合物并有助于同功 tRNA 的选择。