AUTHOR=Park Minji , Cho Yong-Joon , Lee Yang Won , Jung Won Hee 

TITLE=Genomic Multiplication and Drug Efflux Influence Ketoconazole Resistance in Malassezia restricta

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2020.00191

DOI=10.3389/fcimb.2020.00191

ISSN=2235-2988

ABSTRACT=<p><italic>Malassezia restricta</italic> is an opportunistic fungal pathogen on human skin; it is associated with various skin diseases, including seborrheic dermatitis and dandruff, which are usually treated using ketoconazole. In this study, we clinically isolated ketoconazole-resistant <italic>M. restricta</italic> strains (KCTC 27529 and KCTC 27550) from patients with dandruff. To understand the mechanisms of ketoconazole resistance in the isolates, their genomes were sequenced and compared with the susceptible reference strain <italic>M. restricta</italic> KCTC 27527. Using comparative genome analysis, we identified tandem multiplications of the genomic loci containing <italic>ATM1</italic> and <italic>ERG11</italic> homologs in <italic>M. restricta</italic> KCTC 27529 and KCTC 27550, respectively. Additionally, we found that the copy number increase of <italic>ATM1</italic> and <italic>ERG11</italic> is reflected in the increased expression of these genes; moreover, we observed that overexpression of these homologs caused ketoconazole resistance in a genetically tractable fungal pathogen, <italic>Cryptococcus neoformans</italic>. In addition to tandem multiplications of the genomic region containing the <italic>ATM1</italic> homolog, the <italic>PDR5</italic> homolog, which encodes the drug efflux pump protein was upregulated in <italic>M. restricta</italic> KCTC 27529 compared to the reference strain. Biochemical analysis confirmed that drug efflux was highly activated in <italic>M. restricta</italic> KCTC 27529, implying that upregulation of the <italic>PDR5</italic> homolog may also contribute to ketoconazole resistance in the strain. Overall, our results suggest that multiplication of the genomic loci encoding genes involved in ergosterol synthesis, mitochondrial iron metabolism, and oxidative stress response and overexpression of the drug efflux pumps are the mechanisms underlying ketoconazole resistance in <italic>M. restricta</italic>.</p>