Participation of the ABC Transporter CDR1 in Azole Resistance of Candida lusitaniae

Abstract

Candida lusitaniae is an opportunistic pathogen in humans that causes infrequent but difficult-to-treat diseases. Antifungal drugs are used in the clinic to treat C. lusitaniae infections, however, this fungus can rapidly acquire antifungal resistance to all known antifungal drugs (multidrug resistance). C. lusitaniae acquires azole resistance by gain-of-function (GOF) mutations in the transcriptional regulator MRR1. MRR1 controls the expression of a major facilitator transporter (MFS7) that is important for fluconazole resistance. Here, we addressed the role of the ATP Binding Cassette (ABC) transporter CDR1 as additional mediator of azole resistance in C. lusitaniae. CDR1 expression in isolates with GOF MRR1 mutations was higher compared to wild types, which suggests that CDR1 is an additional (direct or indirect) target of MRR1. CDR1 deletion in the azole-resistant isolate P3 (V688G GOF) revealed that MICs of long-tailed azoles, itraconazole and posaconazole, were decreased compared to P3, which is consistent with the role of this ABC transporter in the efflux of these azoles. Fluconazole MIC was only decreased when CDR1 was deleted in the background of an mfs7Δ mutant from P3, which underpins the dominant role of MFS7 in the resistance of the short-tailed azole fluconazole. With R6G efflux readout as Cdr1 efflux capacity, our data showed that R6G efflux was increased in P3 compared to an azole-susceptible wild type parent, and diminished to background levels in mutant strains lacking CDR1. Milbemycin oxim A3, a known inhibitor of fungal ABC transporters, mimicked efflux phenotypes of cdr1Δ mutants. We therefore provided evidence that CDR1 is an additional mediator of azole resistance in C. lusitaniae, and that CDR1 regulation is dependent on MRR1 and associated GOF mutations.

How Yeast Antifungal Resistance Gene Analysis Is Essential to Validate Antifungal Susceptibility Testing Systems

“…We did not observe any increase in MICs when PDR1 was mutated in C. glabrata (except for DSY489) for itraconazole and posaconazole. Indeed, this difference in MIC elevation might be due to the difference of the structure of the long (itraconazole and posaconazole) versus short (fluconazole and voriconazole) side-chain azoles, which impacts their interaction with not only their target but also different transporters as already described ( MacCallum et al., 2010 ; Shafiei et al., 2020 ; Shi et al., 2020 ; Borgeat et al., 2021 ). In addition, we observed as mentioned before ( MacCallum et al., 2010 ) that the presence of only one mechanism of resistance, ERG11 or TAC1 mutations, in C. albicans leads to moderate azoles’ MIC increase, which might be missed by the MNV methods as observed for DSY288 ( Figure 3 ).…”

Effect of new methionine-based ionic liquid on the CDR1 and CDR2 gene expression on sensitive and resistant strains of Candida albicans

“…Fructose administration over than efficient diet could induce fluconazole resistance in C. albicans via the activation of CDR1 and MDR1 transporters ( 43 ). Upregulations of multidrug efflux pumps to belong to the ATP-binding cassette transporters superfamily controlled by CDR1/CDR2 proteins were involved in most C. albicans fluconazole-resistant strains ( 44 ). So in the present study, we investigated the role of the novel ([Met-HCl] [PyS]) on the expression level of these two proteins.…”

Myriocin enhances the antifungal activity of fluconazole by blocking the membrane localization of the efflux pump Cdr1

“…Indeed, loss of Cdr1 resulted in remarkably increased susceptibility of C. albicans to FLC, miconazole, ketoconazole, and itraconazole ( Sanglard et al, 1996 ; Jha et al, 2004 ; Xu et al, 2007 ; Tsao et al, 2009 ; Xu et al, 2021 ). Similarly, the efflux pump protein Cdr1 also plays an important role in the azole resistance of C. glabrata ( Galkina et al, 2020 ), C. auris ( Carolus et al, 2021 ), Candida lusitaniae ( Borgeat et al, 2021 ), Fusarium keratoplasticum ( James et al, 2021 ). In this study, myriocin significantly enhanced the antifungal activity of FLC by blocking membrane localization and inactivating Cdr1.…”

“…However, FLC is a fungistatic agent that cannot kill pathogenic fungi; fungi easily acquire azole resistance ( Perlin et al, 2017 ). Extrusion of FLC from the cell, mediated by an efflux pump Cdr1, is one of the most frequently used strategies for developing FLC resistance in pathogenic fungi ( Kim et al, 2019 ; Teo et al, 2019 ; Borgeat et al, 2021 ). Therefore, pharmacological inactivation of Cdr1 through suppressing the expression of Cdr1, blocking membrane localization of Cdr1, and inhibiting the combination of Cdr1 and antifungal agents, is beneficial to overcoming fungal FLC resistance ( Monk and Goffeau, 2008 ).…”