Related Experiment Video
Updated: Sep 29, 2026
Small-Scale Plasma Membrane Preparation for the Analysis of Candida albicans Cdr1-mGFPHis
Published on: June 13, 2021
Detection of human P-glycoprotein-like molecule in azole-resistant Candida albicans from HIV+ patients
Annarita Stringaro1, Agnese Molinari, Annarica Calcabrini
1Laboratorio di Ultrastrutture, Istituto Superiore di Sanità, Rome, Italy.
Abstract:
Azole resistance in Candida albicans may be due to several mechanisms. It has been demonstrated that C. albicans possesses sequences with a high degree of homology with the human MDR-1 gene coding for P-glycoprotein (P-gp), belonging to the ATP-binding cassette transporter (ABC) superfamily and responsible for the multidrug resistance (MDR) in tumor cells. On this basis, the expression and intracellular localization of human P-gp-like molecule in C. albicans strains showing different sensitivity to fluconazole were investigated by flow cytometry and immunoelectron microscopy. Post-embedding immunolabeling revealed that monoclonal antibody (mAb) MM4.17, which recognizes an external epitope of human P-gp, reacted with both fluconazole-sensitive (3153 and CO 23-1) and fluconazole-resistant (AIDS 68 and CO 23-2, isolated from AIDS patient and in vitro drug-selected, respectively) strains of C. albicans. However, the resistant strains displayed a number of MM4.17-reactive epitopes much higher than the drug-sensitive ones. The C. krusei ATCC 6458 strain, whose resistance is not mediated by the presence of ABC transporters, was not reactive at all with mAb MM4.17. The specificity of the immunolabeling was confirmed by a competitive inhibition assay performed by using phage clone particles capable of mimicking the MM4.17-reactive epitope. The flow cytometric analysis confirmed a higher level of intracytoplasmic P-gp expression in azole-resistant strains of C. albicans. Both cyclosporin A and verapamil, which are well-known MDR inhibitors, strongly reduced the MICs for fluconazole and itraconazole of the tested azole-resistant AIDS 68 strain, while they did not influence the MICs of either the sensitive 3153 strain of C. albicans or the ATCC 6458 strain of C. krusei. Overall, our data suggest the existence of a P-gp-like drug efflux pump in C. albicans that may participate in the mechanisms of azole-resistance of this fungus.
Insights
Azole resistance in Candida albicans may involve a P-glycoprotein (P-gp)-like efflux pump. Resistant strains show higher P-gp expression, which is inhibited by MDR modulators, suggesting a role in antifungal drug resistance.
Area of Science:
- Mycology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Azole antifungal resistance in Candida albicans is a growing clinical concern.
- Candida albicans shares genetic similarities with human multidrug resistance genes, including those for P-glycoprotein (P-gp).
- P-glycoprotein (P-gp) is an ATP-binding cassette (ABC) transporter known to mediate multidrug resistance (MDR) in various organisms.
Purpose of the Study:
- To investigate the expression and localization of a human P-gp-like molecule in Candida albicans.
- To determine the role of this P-gp-like molecule in azole resistance mechanisms.
- To assess the impact of MDR inhibitors on azole susceptibility in Candida albicans.
Main Methods:
- Flow cytometry and immunoelectron microscopy were used to detect and localize P-gp-like molecules.
- Monoclonal antibody (mAb) MM4.17, specific for human P-gp, was employed for immunolabeling.
- Minimum inhibitory concentrations (MICs) were determined for azoles, with and without MDR inhibitors like cyclosporin A and verapamil.
Main Results:
- Resistant Candida albicans strains exhibited significantly higher levels of MM4.17-reactive epitopes compared to sensitive strains.
- Immunolabeling confirmed the presence of P-gp-like molecules, with increased expression in azole-resistant isolates.
- MDR inhibitors (cyclosporin A, verapamil) reduced azole MICs in resistant strains but not in sensitive strains or Candida krusei.
- Candida krusei, lacking ABC transporters, showed no reactivity with the P-gp antibody.
Conclusions:
- The study suggests the presence of a P-gp-like drug efflux pump in Candida albicans.
- This efflux pump likely contributes to the observed azole resistance in this fungal pathogen.
- Targeting this P-gp-like molecule could be a potential strategy to overcome azole resistance in Candida albicans infections.
Related Concept Videos
01:20Candidiasis
01:27Cryptococcal Meningitis