The Bacillus subtilis and Bacillus halodurans Aspartyl-tRNA Synthetases Retain Recognition of tRNA Asn

JOURNAL OF MOLECULAR BIOLOGY

卷:428

Article

Nair, Nilendra¹  Raff, Hannah¹  Islam, Mohammed Tarek¹  Feen, Melanie¹  Garofalo, Denise M.¹  Sheppard, Kelly¹ 

[1] Skidmore Coll, Dept Chem, Saratoga Springs, NY 12866 USA

关键词: AspRS;    asparagine biosynthesis;    GatCAB;    tRNA-dependent biosynthesis;   

DOI  :  10.1016/j.jmb.2016.01.014

来源: Elsevier

【 摘 要 】

Synthesis of asparaginyl-tRNA (Asn-tRNA(Asn)) in bacteria can be formed either by directly ligating Asn to tRNA(Asn) using an asparaginyl-tRNA synthetase (AsnRS) or by synthesizing Asn on the tRNA. In the latter two-step indirect pathway, a non-discriminating aspartyl-tRNA synthetase (ND-AspRS) attaches Asp to tRNA(Asn) and the amidotransferase GatCAB transamidates the Asp to Asn on the tRNA. GatCAB can be similarly used for Gln-tRNA(Gln) formation. Most bacteria are predicted to use only one route for Asn-tRNA(Asn) formation. Given that Bacillus halodurans and Bacillus subtilis encode AsnRS for Asn-tRNA(Asn) formation and Asn synthetases to synthesize Asn and GatCAB for Gln-tRNA(Gln) synthesis, their AspRS enzymes were thought to be specific for tRNA(Asp). However, we demonstrate that the AspRSs are non-discriminating and can be used with GatCAB to synthesize Asn. The results explain why B. subtilis with its Asn synthetase genes knocked out is still an Asn prototroph. Our phylogenetic analysis suggests that this may be common among Firmicutes and 30% of all bacteria. In addition, the phylogeny revealed that discrimination toward tRNA(Asp) by AspRS has evolved independently multiple times. The retention of the indirect pathway in B. subtilis and B. halodurans likely reflects the ancient link between Asn biosynthesis and its use in translation that enabled Asn to be added to the genetic code. (C) 2016 The Authors. Published by Elsevier Ltd.

【 授权许可】

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