Modulation of Substrate Specificity within the Amino Acid Editing Site of Leucyl-tRNA Synthetase

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• 作者：Yuxin Zhai ; Mir Hussain Nawaz ; Keun Woo Lee ; Erin Kirkbride ; James M. Briggs ; Susan A. Martinis
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：March 20, 2007
• 年：2007
• 卷：46
• 期：11
• 页码：3331 - 3337
• 全文大小：356K
• 年卷期：v.46,no.11(March 20, 2007)
• ISSN：1520-4995

文摘

The aminoacyl-tRNA synthetases covalently link transfer RNAs to their cognate amino acids.Some of the tRNA synthetases have evolved editing mechanisms to ensure fidelity in this first step ofprotein synthesis. The amino acid editing site for leucyl- (LeuRS) and isoleucyl- (IleRS) tRNA synthetasesreside within homologous CP1 domains. In each case, a threonine-rich peptide and a second conservedGTG region that are separated by about 100 amino acids comprise parts of the hydrolytic editing site.While a number of sites are conserved between these two enzymes and likely confer a commonality tothe mechanisms, some positions are idiosyncratic to LeuRS or IleRS. Herein, we provide evidence thata conserved arginine and threonine at respective sites in LeuRS and IleRS diverged to confer amino acidsubstrate recognition. This site complements other sites in the amino acid binding pocket of the editingactive site of Escherichia coli LeuRS, including Thr²⁵² and Val³³⁸, which collectively fine-tune aminoacid specificity to confer fidelity.