Genetic modification ofCandida maltosa, a nonpathogenic CTG species, revealsEFG1function

Abstract

ABSTRACTCandida maltosais closely related to important pathogenicCandidaspecies, but it has been rarely isolated from humans. Therefore, through comparative studies, it could be a powerful model to understand the pathogenicity underpinnings ofCandidaspecies. To facilitate studyingC. maltosaat a molecular level, we built a cohesive genomic sequence composed of 45 scaffolds, a substantial improvement from the thousands of contigs of the available draft. Comparison withC. albicansandC. tropicalisrevealed a reduction in the total number of genes inC. maltosa. However, gene loss seems not to be associated to its avirulence given that most pathogenicity genes were also present inC. maltosa. To genetically editC. maltosawe generated triple auxotrophic strains so that gene deletions can be performed as has been routinely done in pathogenic species. As a proof of concept, we generated gene knockouts of Efg1, a transcription regulator involved in filamentation and biofilm formation in pathogenic species. Although inC. maltosaEfg1 also played a role in these processes, it seems to rather be a repressor of filamentation. The genome assembly and auxotrophic mutants developed are a key step to start usingC. maltosafor comparative studies at a molecular level.