Nonsense and Missense Mutations in FCY2 and FCY1 Genes Are Responsible for Flucytosine Resistance and Flucytosine-Fluconazole Cross-Resistance in Clinical Isolates of Candida lusitaniae

• DOI: 10.1128/aac.00880-08
• Publication Date: 2009-05-05T01:29:27Z
• Authors: Martine Florent; Thierry Noël; Gwenaël Ruprich-...; Bruno Da Silva; Valérie Fitton-O...; Christiane Chastin; Nicolas Papon; Florence Chapelan...
• Keywords: Nonsense mutation; Flucytosine; Cytosine

The aim of this work was to elucidate the molecular mechanisms flucytosine (5FC) resistance and 5FC/fluconazole (FLC) cross-resistance in 11 genetically epidemiologically unrelated clinical isolates Candida lusitaniae. We first showed that levels transcription FCY2 gene encoding purine-cytosine permease (PCP) were similar wild-type strain, 6936. Nucleotide sequencing alleles revealed 5FC 5FC/FLC could be correlated with a cytosine-to-thymine substitution at nucleotide 505 fcy2 genes seven isolates, resulting nonsense mutation putative nonfunctional truncated PCP 168 amino acids. Reintroducing allele locus ura3 auxotrophic strain derived from isolate CL38 fcy2(C505T) restored susceptibility antifungals comparable those strains. In remaining four polymorphic found FCY1 where T26C resulted acid replacement M9T cytosine deaminase. Introducing mutated into 5FC- 5FC/FLC-resistant fcy1Delta failed restore antifungal susceptibility, while obtained by introducing allele. thus correlation between fcy1 both resistances. demonstrated only two genetic events occurred C. lusitaniae support resistance: either C505T or missense gene.