title: Fluconazole resistance in Candida glabrata is associated with increased bud formation and metallothionein production.
abstract: Virulence associated with fluconazole (FL) resistance in Candida glabrata is a global problem and has not been well characterized at the proteome level. In this study, a stable FL-resistant (MIC >256 µg ml(-1)) strain of C. glabrata was generated on agar containing FL. Eight phenotypic mutants were characterized by contour-clamped homogeneous electrophoretic field analysis and two-dimensional PAGE. The secondary derivatives of C. glabrata yielded four distinct genotypes with varying chromosomal profiles. Proteomic analysis performed by tandem mass spectrometry for two of the mutants, CG(L2) and CG(S3), demonstrated a total of 25 differentially regulated proteins of which 13 were upregulated and 12 were downregulated or were similar compared with the parental isolate. The mRNA transcript levels of significantly (P<0.001) upregulated genes were determined by quantitative RT-PCR analysis, and their physiological relevance in terms of phenotypic expression of virulence attributes was verified by conventional laboratory methodologies. The data showed that the FL resistance (MIC >256 µg ml(-1)) of CG(S3) was associated with significantly upregulated (P<0.001) mRNA transcript levels of several genes - ERG11, CDR1, CDR2, MFS, MTI, TPR, VPS and EFT2 - in addition to a number of other potentially virulent genes expressed differentially at a lower level. The results demonstrated accentuated phenotypic expression of bud formation of yeast and metallothionein production associated with FL resistance in C. glabrata, which may help the fungus to colonize the host.
authors.affiliation: Oral Bio-sciences, Faculty of Dentistry, University of Hong Kong, Hong Kong SAR.
authors.forename: Y H
authors.initials: YH
authors.lastname: Samaranayake
authors.affiliation: Oral Bio-sciences, Faculty of Dentistry, University of Hong Kong, Hong Kong SAR.
authors.forename: B P K
authors.initials: BPK
authors.lastname: Cheung
authors.affiliation: Department of Pharmacology and Pharmacy, University of Hong Kong, Hong Kong SAR.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Oral Bio-sciences, Faculty of Dentistry, University of Hong Kong, Hong Kong SAR.
authors.forename: J Y Y
authors.initials: JYY
authors.lastname: Yau
authors.affiliation: Oral Bio-sciences, Faculty of Dentistry, University of Hong Kong, Hong Kong SAR.
authors.forename: K W S
authors.initials: KWS
authors.lastname: Yeung
authors.affiliation: Oral Bio-sciences, Faculty of Dentistry, University of Hong Kong, Hong Kong SAR.
authors.forename: L P
authors.initials: LP
authors.lastname: Samaranayake
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology; D041221:Candida glabrata / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D002177:Candidiasis / Q000188:drug therapy / Q000382:microbiology; D004271:DNA, Fungal / Q000235:genetics; D025141:Drug Resistance, Fungal / Q000235:genetics*; D015725:Fluconazole / Q000378:metabolism / Q000494:pharmacology*; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008668:Metallothionein / Q000096:biosynthesis*; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D040901:Proteomics; D012333:RNA, Messenger / Q000096:biosynthesis; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000935:Antifungal Agents; D004271:DNA, Fungal; D005656:Fungal Proteins; D012333:RNA, Messenger; D037521:Virulence Factors; D015725:Fluconazole; D008668:Metallothionein