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Important role of the amino acid attached to tRNA in formylation and in initiation of protein synthesis in Escherichia coli

Li, Shihong and Kumar, Vinay N and Varshney, Umesh and RajBhandary, Uttam L (1996) Important role of the amino acid attached to tRNA in formylation and in initiation of protein synthesis in Escherichia coli. In: Journal of Biological Chemistry, 271 (2). pp. 1022-1028. (In Press)

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In attempts to convert an elongator tRNA to an initiator tRNA, we previously generated a mutant elongator methionine tRNA carrying an anticodon sequence change from CAU to CUA along with the two features important for activity of Escherichia coli initiator tRNA in initiation. This mutant tRNA (Mi:2 tRNA) was active in initiation in vivo but only when aminoacylated with methionine by overproduction of methionyl-tRNA synthetase. Here we show that the Mi:2 tRNA is normally aminoacylated in vivo with lysine and that the tRNA aminoacylated with lysine is a very poor substrate for formylation compared with the same tRNA aminoacylated with methionine. By introducing further changes at base pairs 4:69 and 5:68 in the acceptor stem of the Mi:2 tRNA to those found in the E. coli initiator tRNA, we show that change of the U4:A69 base pair to G4:C69 and overproduction of lysyl-tRNA synthetase and methionyl-tRNA transformylase results in partial formylation of the mutant tRNA and activity of the formyllysyl-tRNAs in initiation of protein synthesis. Thus, the G4:C69 base pair contributes toward formylation of the tRNA and protein synthesis in E. coli can be initiated with formyllysine. We also discuss the implications of these and other results on recognition of tRNAs by E. coli lysyl-tRNA synthetase and on competition in cells among aminoacyl-tRNA synthetases.

Item Type: Journal Article
Publication: Journal of Biological Chemistry
Publisher: The american society for biochemistry and molecular biology
Additional Information: Copyright of this article belongs to The American Society for Biochemistry and Molecular Biology.
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 29 Apr 2011 08:09
Last Modified: 22 Nov 2018 15:04
URI: http://eprints.iisc.ac.in/id/eprint/37307

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