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

• Type: Article in International Scientific Journal
• Date: 2002

Authors

Moura, G (Author) Other; miranda, im (Author) Other; Cheesman, C (Author) Other; Tuite, MF (Author) Other; Santos, MAS (Author) Other

Journal

Title: Yeast

Vol. 19

Pages: 727-733

ISSN: 0749-503X

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 2 Citations

Scopus - 3 Citations

Other information

Authenticus ID: P-000-NZY

DOI: 10.1002/yea.874

Abstract (EN): 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 sertRNA(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 readtbrough 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-tRNACAG is decoding of the leu-CUG codon as serine. Copyright (C) 2002 John Wiley Sons, Ltd.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7