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| Subject Categories: Proteins | Microbiology & Pathogens |
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| The EMBO Journal
(2003) 22, 651–656, doi:10.1093/emboj/cdg072 |
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| In vivo evidence for the prokaryotic model of extended codon–anticodon interaction in translation initiation |
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| Donna Esposito1, 2, 3, 6, Julien P. Fey1, 4, 5, 6, Stephan Eberhard5, Amanda J. Hicks1 and David B. Stern1 |
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1 Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY 14853, USA 2 Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA 3 Present address: Charles River Laboratories, Troy, NY 12180-7617, USA 4 Present address: Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, OR 97201, USA 5 Institut de Biologie Physico-Chimique du CNRS (UPR 1261), 13 rue Pierre et Marie Curie, 75005 Paris, France 6 D.Esposito and J.P.Fey contributed equally to this work To whom correspondence should be addressed David B. Stern, ds28@cornell.edu Received 30 October 2002; Revised 6 December 2002; Accepted 9 December 2002. |
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| Abstract |
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| Initiation codon context is an important determinant of translation initiation rates in both prokaryotes and eukaryotes. Such sequences include the Shine– Dalgarno ribosome-binding site, as well as other motifs surrounding the initiation codon. One proposed interaction is between the base immediately preceding the initiation codon (-1 position) and the nucleotide 3' to the tRNAfMet anticodon, at position 37. Adenine is conserved at position 37, and a uridine at -1 has been shown in vitro to favor initiation. We have tested this model in vivo, by manipulating the chloroplast of the green alga Chlamydomonas reinhardtii, where the translational machinery is prokaryotic in nature. We show that translational defects imparted by mutations at the petA -1 position can be suppressed by compensatory mutations at position 37 of an ectopically expressed tRNAfMet. The mutant tRNAs are fully aminoacylated and do not interfere with the translation of other proteins. Although this extended base pairing is not an absolute requirement for initiation, it may convey added specificity to transcripts carrying non-standard initiation codons, and/or preserve translational fidelity under certain stress conditions. |
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| Keywords: anticodon, Chlamydomonas, chloroplast, initiator tRNA |
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