Stop codon decoding in Candida albicans: from non-standard back to standard

Moura, G. and Miranda, I. and Cheesman, C. and Tuite, M.F. and Santos, M.A. (2002) Stop codon decoding in Candida albicans: from non-standard back to standard. Yeast, 19 (9). pp. 727-733. ISSN 0749-503X. (The full text of this publication is not available from this repository)

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Abstract

The human pathogen Candida albicans translates the standard leucine-CUG codon as serine. This genetic code change is mediated by a novel ser-tRNA(CAG), which induces aberrant mRNA decoding in vitro, resulting in retardation of the electrophoretic mobility of the polypeptides synthesized in its presence. These non-standard decoding events have been attributed to readthrough of the UAG and UGA stop codons encoded by the Brome Mosaic Virus RNA 4, which codes for the virion coat protein, and the rabbit globin mRNAs, respectively. In order to fully elucidate the behaviour of the C. albicans ser-tRNA(CAG) towards stop codons, we have used other cell-free translation systems and reporter genes. However, the reporter systems used encode several CUG codons, making it impossible to distinguish whether the slow migration of the polypeptides is caused by the replacement of leucines by serines at the CUG codons, readthrough, or a combination of both. Therefore, we have constructed new reporter systems lacking CUG codons and have used them to demonstrate that aberrant mRNA decoding in vitro is not a result from stop codon readthrough or any other non-standard translational event. Our data show that a single leucine to serine replacement at only one of the four CUG codons encoded by the BMV RNA-4 gene is responsible for the aberrant migration of the BMV coat protein on SDS-PAGE, suggesting that this amino acid substitution (ser for leu) significantly alters the structure of the virion coat protein. The data therefore show that the only aberrant event mediated by the ser-tRNA(CAG) is decoding of the leu-CUG codon as serine.

Item Type: Article
Additional information: 0749-503X (Print) Journal Article Research Support, Non-U.S. Gov't
Uncontrolled keywords: Amino Acid Substitution Bromovirus/genetics Candida albicans/*genetics Capsid/genetics *Codon, Terminator Genes, Reporter Leucine/genetics Protein Biosynthesis RNA, Fungal RNA, Messenger RNA, Transfer, Ser RNA, Viral/genetics Serine/genetics
Subjects: Q Science > QR Microbiology
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences > Protein Science Group
Depositing User: Mick Tuite
Date Deposited: 09 Sep 2008 17:00
Last Modified: 14 Jan 2010 14:20
Resource URI: http://kar.kent.ac.uk/id/eprint/5469 (The current URI for this page, for reference purposes)
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