Activation of the pyrrolysine suppressor tRNA requires formation of a ternary complex with class I and class II lysyl-tRNA synthetases
Activation of the pyrrolysine suppressor tRNA requires formation of a ternary complex with class I and class II lysyl-tRNA synthetases
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DOI：
10.1016/s1097-2765(03)00280-6
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发表时间：
2003-08-01
期刊：
影响因子：
16
通讯作者：
Söll, D
中科院分区：
文献类型：
--
作者：
Polycarpo, C;Ambrogelly, A;Söll, D
巴氏甲烷链霉菌的单甲胺甲基转移酶含有一种罕见的氨基酸--吡咯赖氨酸，由终止密码子UAG编码。该UAG的翻译需要相应的琥珀抑制因子tRNA(PYL)的氨基酰化。以前的研究报道，tRNA(Pyl)可以被合成酶样蛋白PyIS氨基酰化。我们现在证明，tRNA(PYL)在Barkeri的I类LysRS和II类LysRS的存在下都能有效地氨基酰化，但不能被单独作用的酶或PYIS所作用。体外研究表明，I类和II类LysRS酶都必须与tRNA(Pyl)结合才能进行氨基酰化反应。结构模拟和选择性抑制实验表明，I类和II类LysRSs与tRNA(Pyl)形成三元络合物，其氨酰化活性位于II类酶中。
Monomethylamine methyltransferase of the archaeon Methanosarcina barkeri contains a rare amino acid, pyrrolysine, encoded by the termination codon UAG. Translation of this UAG requires the aminoacylation of the corresponding amber suppressor tRNA(Pyl). Previous studies reported that tRNA(Pyl) could be amino acylated by the synthetase-like protein PyIS. We now show that tRNA(Pyl) is efficiently aminoacylated in the presence of both the class I LysRS and class II LysRS of M. barkeri, but not by either enzyme acting alone or by PyIS. In vitro studies show that both the class I and II LysRS enzymes must bind tRNA(Pyl) in order for the aminoacylation reaction to proceed. Structural modeling and selective inhibition experiments indicate that the class I and II LysRSs form a ternary complex with tRNA(Pyl), with the aminoacylation activity residing in the class II enzyme.