The 51–63 base pair of tRNA confers specificity for binding by EF-Tu
Abstract
Elongation factor Tu (EF-Tu) exhibits significant specificity for the different elongator tRNA bodies in order to offset its variable affinity to the esterified amino acid. Three X-ray cocrystal structures reveal that while most of the contacts with the protein involve the phosphodiester backbone of tRNA, a single hydrogen bond is observed between the Glu390 and the amino group of a guanine in the 51–63 base pair in the T-stem of tRNA. Here we show that the Glu390Ala mutation of Thermus thermophilus EF-Tu selectively destabilizes binding of those tRNAs containing a guanine at either position 51 or 63 and that mutagenesis of the 51–63 base pair in several tRNAs modulates their binding affinities to EF-Tu. A comparison of Escherichia coli tRNA sequences suggests that this specificity mechanism is conserved across the bacterial domain. While this contact is an important specificity determinant, it is clear that others remain to be identified.
Keywords
Footnotes
-
Reprint requests to: Olke C. Uhlenbeck, Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2205 Tech Drive, Hogan 2-100, Evanston, IL 60208, USA; e-mail: o-uhlenbeck{at}northwestern.edu; fax: (847) 491-5444.
-
Abbreviations: EF-Tu, elongation factor Tu; aa-tRNA, aminoacyl-tRNA.
-
Article published online ahead of print. Article and publication date are at http://www.rnajournal.org/cgi/doi/10.1261/rna.485307.
-
- Received January 29, 2007.
- Accepted March 7, 2007.
- Copyright © 2007 RNA Society
