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Presence of the Hypermodified Nucleotide N6-(Delta 2-isopentenyl)-2-methylthioadenosine Prevents Codon Misreading by Escherichia coli Phenylalanyl-Transfer RNA

Wilson, Richard K. and Roe, Bruce A. (1989) Presence of the Hypermodified Nucleotide N6-(Delta 2-isopentenyl)-2-methylthioadenosine Prevents Codon Misreading by Escherichia coli Phenylalanyl-Transfer RNA. Proceedings of the National Academy of Sciences of the United States of America, 86 (2). pp. 409-413. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:WILpnas89

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Abstract

The overall structure of transfer RNA is optimized for its various functions by a series of unique post-transcriptional nucleotide modifications. Since many of these modifications are conserved from prokaryotes through higher eukaryotes, it has been proposed that most modified nucleotides serve to optimize the ability of the tRNA to accurately interact with other components of the protein synthesizing machinery. When a cloned synthetic Escherichia coli tRNAPhe gene was transfected into a bacterial host that carried a defective phenylalanine tRNA-synthetase gene, tRNAPhe was overexpressed by 11-fold. As a result of this overexpression, an undermodified tRNAPhe species was produced that lacked only N6-(Delta 2-isopentenyl)-2-methylthioadenosine (ms2i6A), a hypermodified nucleotide found immediately 3' to the anticodon of all major E. coli tRNAs that read UNN codons. To investigate the role of ms2i6A in E. coli tRNA, we compared the aminoacylation kinetics and in vitro codon-reading properties of the ms2i6A-lacking and normal fully modified tRNAPhe species. The results of these experiments indicate that while ms2i6A is not required for normal aminoacylation of tRNAPhe, its presence stabilizes codon-anticodon interaction and thereby prevents misreading of the genetic code.


Item Type:Article
Additional Information:Copyright © 1989 by the National Academy of Sciences Communicated by John Abelson, October 7, 1988 We thank Drs. J. Tang and K. Jackson for performing the protein radiosequencing analyses. This work was supported by National Institutes of Health Grant GM30400. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Subject Keywords:tRNA genes; wobble hypothesis; in vitro translation
Record Number:CaltechAUTHORS:WILpnas89
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:WILpnas89
Alternative URL:http://www.pnas.org/cgi/content/abstract/86/2/409
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6197
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:28 Nov 2006
Last Modified:14 Nov 2014 19:19

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