Original article: In vitro and in vivo cell surface expression of a thiol-specific antioxidant-like protein in Candida albicans

• Published in: Journal de mycologie médicale 2005-03, Vol.15 (1), p.1-12
• Main Authors: Apaire-Marchais, V, Cottin, J, Marot-Leblond, A, Lefrancois, C, Tronchin, G, Robert, R
• Format: Article
• Language: English
• Subjects: Candida albicans; Saccharomyces cerevisiae
• ISSN: 1156-5233
• DOI: 10.1016/j.mycmed.2004.12.001

Objective. - Among potential virulence factors of Candida albicans, are hydrophobic hyphal surface proteins. Methods. - A cDNA library was therefore constructed from germ tube mRNAs, and immunoscreened with a rabbit immune serum raised against purified hydrophobic hyphal proteins. Results. - Analysis of the nucleotide and deduced amino acid sequences of one selected clone revealed an open reading frame encoding a protein of 196 amino acid residues with a molecular mass of 25-kDa. Significant homology was shown with a class of thiol-specific antioxidant (Tsa) like enzymes present in prokaryotes and eukaryotes. A 73% identity was obtained with Saccharomyces cerevisiae Tsa1p. Reverse transcription-quantitative PCR showed the expression of C. albicans TSA-like gene in both blastoconidia and germ tubes, with a 15-fold overexpression in germ tubes. However, in vitro studies using anti-peptide antibodies and confocal microscopy demonstrated the presence of the corresponding protein at the surface of the hyphal part of germ tubes exclusively. Conclusion. - In conclusion, this protein which was synthesized in both blastoconidia and germ tubes, was expressed at the surface of the invasive forms in vitro, but also in vivo in a murine model. Therefore, it could play a role in pathogenesis of C. albicans. Resume Objectif. - Les proteines hyphales hydrophobes de surface comptent parmi les facteurs de virulence potentiels de Candida albicans. Methodes. - Ainsi, une banque d'ADNc a ete construite a partir d'ARNm de tubes germinatifs, et immunocriblee avec un immunserum de lapin dirige contre les proteines hyphales hydrophobes purifiees. Resultats. - L'analyse de la sequence nucleotidique et de la sequence d'acides amines deduite de l'un des clones selectionne a revele un cadre ouvert de lecture codant une proteine de 196 acides amines ayant une masse moleculaire de 25 kDa. Une homologie significative de cette sequence a ete montree avec les sequences d'une classe d'enzymes antioxydantes, thiol-specifiques, presentes chez les procaryotes et les eucaryotes. Une identite de 73% a ete obtenue avec la proteine Tsa1 de Saccharomyces cerevisiae. La RT-PCR quantitative a montre l'expression du gene TSA-like de C. albicans a la fois pour la forme blastospore et pour la forme tube germinatif, avec une sur-expression de 15 fois pour ces tubes germinatifs. Des etudes complementaires in vitro, utilisant des anticorps anti-peptides et la microscopie confocale, ont demontre la presence