Discovery and characterization of tRNAIle lysidine synthetase (TilS)

Suzuki, Tsutomu; Miyauchi, Kenjyo

doi:10.1016/j.febslet.2009.11.085

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Volume 584, Issue 2 , Pages 272-277, 21 January 2010

Discovery and characterization of tRNA^Ile lysidine synthetase (TilS)

Edited by Manuel Santos

Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Received 12 November 2009; received in revised form 21 November 2009; accepted 24 November 2009. published online 27 November 2009.

Abstract

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.

Keywords: tRNA, Lysidine, TilS, AUA codon, Wobble modification, Anticodon