The natural occurring Y129F polymorphism in Rhizopus oryzae (R. arrhizus ) Cyp51Ap accounts for its intrinsic voriconazole resistance

MACEDO, DAIANA; LEONARDELLI, FLORENCIA; CABEZA, MATIAS S; GAMARRA, SOLEDAD; GARCIA-EFFRON, GUILLERMO

MEDICAL MYCOLOGY

TAYLOR & FRANCIS LTD

Año: 2021

1369-3786

Rhizopus oryzae (heterotypic synonym: R. arrhizus) intrinsic voriconazole and fluconazole resistance hasbeen linked to its CYP51A gene. However, the amino acid residues involved in this phenotype have not yetbeen established. A comparison between R. oryzae and Aspergillus fumigatus Cyp51Ap sequences showeddifferences in several amino acid residues. Some of them were already linked with voriconazole resistancein A. fumigatus. The objective of this work was to analyze the role of two natural polymorphisms in theintrinsic voriconazole resistance phenotype of R. oryzae (Y129F and T290A, equivalent to Y121F and T289Aseen in triazole-resistant A. fumigatus). We have generated A. fumigatus chimeric strains harboring differentR. oryzae CYP51A genes (wild-type and mutants). These mutant R. oryzae CYP51A genes were designedto carry nucleotide changes that produce mutations at Cyp51Ap residues 129 and 290 (emulatingthe Cyp51Ap protein of azole susceptible A. fumigatus). Antifungal susceptibilities were evaluated for all theobtained mutants. The polymorphism T290A (alone or in combination with Y129F) had no impact on triazoleMIC. On the other hand, a > 8-fold decrease in voriconazole MICs was observed in A. fumigatus chimericstrains harboring the RoCYP51Ap-F129Y. This phenotype supports the assumption that the naturally occurringpolymorphism Y129F at R. oryzae Cyp51Ap is responsible for its voriconazole resistance phenotype. Inaddition, these chimeric mutants were posaconazole hypersusceptible. Thus, our experimental data demonstratethat the RoCYP51Ap-F129 residue strongly impacts VRC susceptibility and that it would be related withposaconazole-RoCYP51Ap interaction.