Suzuki Tsutomu, Miyauchi Kenjyo
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
FEBS Lett. 2010 Jan 21;584(2):272-7. doi: 10.1016/j.febslet.2009.11.085.
In the bacterial decoding system, the AUA codon is deciphered as isoleucine by tRNA(Ile) bearing lysidine (L, 2-lysyl-cytidine) at the wobble position. Lysidine is an essential modification that determines both the codon and amino acid specificities of tRNA(Ile). We identified an enzyme named tRNA(Ile) lysidine synthetase (TilS) that catalyzes lysidine formation by using lysine and ATP as substrates. Biochemical studies revealed a molecular mechanism of lysidine formation that consists of two consecutive reactions involving the adenylated tRNA intermediate. In addition, we deciphered how Escherichia coli TilS specifically discriminates between tRNA(Ile) and the structurally similar tRNA(Met), which bears the same anticodon loop. Recent structural studies unveiled tRNA recognition by TilS, and a molecular basis of lysidine formation at atomic resolution.
在细菌解码系统中，AUA密码子被位于摆动位置带有赖氨酸idine（L，2-赖氨酰胞苷）的tRNA（Ile）解读为异亮氨酸。赖氨酸idine是一种关键修饰，它决定了tRNA（Ile）的密码子和氨基酸特异性。我们鉴定出一种名为tRNA（Ile）赖氨酸idine合成酶（TilS）的酶，它以赖氨酸和ATP为底物催化赖氨酸idine的形成。生化研究揭示了赖氨酸idine形成的分子机制，该机制由涉及腺苷酸化tRNA中间体的两个连续反应组成。此外，我们还解读了大肠杆菌TilS如何特异性区分tRNA（Ile）和结构相似但带有相同反密码子环的tRNA（Met）。最近的结构研究揭示了TilS对tRNA的识别以及原子分辨率下赖氨酸idine形成的分子基础。
