In the United States, candidemia is one of the most common hospital-acquired infections and is estimated to cause 10,000 deaths per year. The species Candida albicans is responsible for the majority of these cases. As C. albicans is capable of developing resistance against the currently available drugs, understanding the molecular basis of drug resistance, finding new cellular targets, and further understanding the overall mechanism of C. albicans pathogenesis are important goals. To study this pathogen it is advantageous to manipulate its genome. Numerous strategies of C. albicans gene manipulation have been introduced. This review evaluates a majority of these strategies and should be a helpful guide for researchers to identify gene targeting strategies to suit their requirements.

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Candida albicans is a fungal pathogen that causes potentially fatal infections among immune-compromised individuals. The emergence of drug resistant C. albicans strains makes it important to identify new antifungal drug targets. Among potential targets are enzymes known as peptidyl-prolyl cis/trans isomerases (PPIases) that catalyze isomerization of peptide bonds preceding proline. We are investigating a PPIase called Ess1, which is conserved in all major human pathogenic fungi. Previously, we reported that C. albicans Ess1 is essential for growth and morphogenetic switching. In the present study, we re-evaluated these findings using more rigorous genetic analyses, including the use of additional CaESS1 mutant alleles, distinct marker genes, and the engineering of suitably-matched isogenic control strains. The results confirm that CaEss1 is essential for growth in C. albicans, but show that reduction of CaESS1 gene dosage by half (δ/+) does not interfere with morphogenetic switching. However, further reduction of CaEss1 levels using a conditional allele does reduce morphogenetic switching. We also examine the role of the linker α-helix that distinguishes C. albicans Ess1 from the human Pin1 enzyme, and present results of a genome-wide transcriptome analysis. The latter analysis indicates that CaEss1 has a conserved role in regulation of RNA polymerase II function, and is required for efficient termination of small nucleolar RNAs and repression of cryptic transcription in C. albicans.