A lacZ reporter with high activity in the human fungal pathogen Candida albicans

Reporter genes are useful tools to study gene transcription in various organisms. For example, the lacZ gene encoding beta-galactosidase has been extensively used as a reporter in bacteria, budding yeast, fruit fly, mouse etc. However, use of this gene in the human fungal pathogen Candida albicans has been limited, probably due to low beta-galactosidase activity. Here, we describe a reporter derived from the Vibrio cholerae lacZ gene in which codons have been optimized for expression in C. albicans. The constitutively active ACT1 promoter was fused to this synthetic lacZ reporter and integrated in the C. albicans genome. High beta-galactosidase activity in liquid assays was observed for this reporter as well as coloration on X-gal plates. When the lacZ reporter expression was driven by the MET3 promoter, beta-galactosidase activity in liquid assays and coloration on X-gal plates was higher in the absence of methionine, thus recapitulating the regulation of the native MET3 gene. This synthetic lacZ gene extends the toolbox of C. albicans reagents by providing a useful reporter for analysis of promoter activity in this organism of medical importance.