Selective advantages created by codon ambiguity allowed for the evolution of an alternative genetic code in Candida spp

Santos, Manuel and Cheesman, Caroline and Costa, Vitor Santos and Moradas-Ferreira, Pedro and Tuite, Mick F. (1999) Selective advantages created by codon ambiguity allowed for the evolution of an alternative genetic code in Candida spp. Molecular Microbiology, 31 (3). pp. 937-947. ISSN 0950-382X. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Several species of the genus Candida decode the standard leucine CUG codon as serine, This and other deviations from the standard genetic code in both nuclear and mitochondrial genomes invalidate the notion that the genetic code is frozen and universal and prompt the questions 'why alternative genetic codes evolved and, more importantly, how can an organism survive a genetic code change?' To address these two questions, we have attempted to reconstruct the early stages of Candida albicans CUG reassignment in the closely related yeast Saccharomyces cerevisiae, These studies suggest that this genetic code change was driven by selection using a molecular mechanism that requires CUG ambiguity. Such codon ambiguity induced a significant decrease in fitness, indicating that CUG reassignment can only be selected if it introduces an evolutionary edge to counteract the negative impact of ambiguity. We have shown that CUG ambiguity induces the expression of a novel set of stress proteins and triggers the general stress response, which, in turn, creates a competitive edge under stress conditions. In addition, CUG ambiguity in S. cerevisiae induces the expression of a number of novel phenotypes that mimic the natural resistance to stress characteristic of C. albicans. The identification of an evolutionary advantage created by CUG ambiguity is the first experimental evidence for a genetic code change driven by selection and suggests a novel role for codon reassignment in the adaptation to new ecological niches.

Item Type: Article
Subjects: Q Science
Q Science > QD Chemistry
Q Science > QH Natural history > QH301 Biology
Q Science > QR Microbiology
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: F.D. Zabet
Date Deposited: 26 Mar 2009 18:16
Last Modified: 10 Jun 2014 12:45
Resource URI: (The current URI for this page, for reference purposes)
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