Calabrese David, Bille Jacques, Sanglard Dominique
Institut de Microbiologie, Centre Hospitalier Universitaire Vaudois (CHUV), Rue de Bugnon, CH-1011 Lausanne, Switzerland1.
Microbiology (Reading). 2000 Nov;146 ( Pt 11):2743-2754. doi: 10.1099/00221287-146-11-2743.
Azole resistance in Candida albicans can be mediated by several resistance mechanisms. Among these, alterations of the azole target enzyme and the overexpression of multidrug efflux transporter genes are the most frequent. To identify additional putative azole resistance genes in C. albicans, a genomic library from this organism was screened for complementation of fluconazole hypersusceptibility in Saccharomyces cerevisiae YKKB-13 lacking the ABC (ATP-binding cassette) transporter gene PDR5. Among the C. albicans genes obtained, a new gene was isolated and named FLU1 (fluconazole resistance). The deduced amino acid sequence of FLU1 showed similarity to CaMDR1 (formerly BEN(r)), a member of the major facilitator superfamily of multidrug efflux transporters. The expression of FLU1 in YKKB-13 mediated not only resistance to fluconazole but also to cycloheximide among the different drugs tested. The disruption of FLU1 in C. albicans had only a slight effect on fluconazole susceptibility; however, it resulted in hypersusceptibility to mycophenolic acid, thus suggesting that this compound could be a substrate for the protein encoded by FLU1. Disruption of FLU1 in a background of C. albicans mutants with deletions in several multidrug efflux transporter genes, including CDR1, CDR2 and CaMDR1, resulted in enhanced susceptibility to several azole derivatives. FLU1 expression did not vary significantly between several pairs of azole-susceptible and azole-resistant C. albicans clinical isolates. Therefore, FLU1 seems not to be required for the development of azole resistance in clinical isolates.
白色念珠菌中的唑类耐药性可由多种耐药机制介导。其中，唑类靶酶的改变和多药外排转运蛋白基因的过表达最为常见。为了鉴定白色念珠菌中其他可能的唑类耐药基因，利用缺乏ABC（ATP结合盒）转运蛋白基因PDR5的酿酒酵母YKKB - 13对该菌的基因组文库进行筛选，以寻找对氟康唑超敏感的互补基因。在获得的白色念珠菌基因中，分离出一个新基因并命名为FLU1（氟康唑耐药）。FLU1推导的氨基酸序列与CaMDR1（原BEN(r)）相似，CaMDR1是多药外排转运蛋白主要易化子超家族的成员。在测试的不同药物中，FLU1在YKKB - 13中的表达不仅介导了对氟康唑的耐药性，还介导了对环己酰亚胺的耐药性。白色念珠菌中FLU1的缺失对氟康唑敏感性仅有轻微影响；然而，它导致对霉酚酸超敏感，因此表明该化合物可能是FLU1编码蛋白的底物。在包括CDR1、CDR2和CaMDR1在内的几个多药外排转运蛋白基因缺失的白色念珠菌突变体背景下，FLU1的缺失导致对几种唑类衍生物的敏感性增强。在几对唑类敏感和唑类耐药的白色念珠菌临床分离株之间，FLU1的表达没有显著差异。因此，FLU1似乎不是临床分离株中唑类耐药性产生所必需的。
