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Updated: Dec 14, 2025
Bio-energetics Investigation of Candida albicans Using Real-time Extracellular Flux Analysis
Published on: March 19, 2019
An Erg11 lanosterol 14-α-demethylase-Arv1 complex is required for Candida albicans virulence
Michelle L Villasmil1, Antonio Daniel Barbosa2, Jessie Lee Cunningham1
1Institute of Metabolic Disorders, Genesis Biotechnology Group, Hamilton, New Jersey, United States of America.
Abstract:
Azole resistant fungal infections remain a health problem for the immune compromised. Current therapies are limited due to rises in new resistance mechanisms. Therefore, it is important to identify new drug targets for drug discovery and novel therapeutics. Arv1 (are1 are2 required for viability 1) function is highly conserved between multiple pathogenic fungal species. Candida albicans (C. albicans) cells lacking CaArv1 are azole hypersusceptible and lack virulence. Saccharomyces cerevisiae (S. cerevisiae) Scarv1 cells are also azole hypersusceptible, a phenotype reversed by expression of CaArv1, indicating conservation in the molecular mechanism for azole susceptibility. To define the relationship between Arv1 function and azole susceptibility, we undertook a structure/function analysis of ScArv1. We identified several conserved amino acids within the ScArv1 homology domain (ScAhd) required for maintaining normal azole susceptibility. Erg11 lanosterol 14-α-demethylase is the rate-limiting enzyme in sterol biosynthesis and is the direct target of azole antifungals, so we used our ScArv1 mutants in order to explore the relationship between ScArv1 and ScErg11. Specific ScArv1 mutants ectopically expressed from a low copy plasmid were unable to restore normal azole susceptibility to Scarv1 cells and had reduced Erg11 protein levels. Erg11 protein stability depended on its ability to form a heterodimeric complex with Arv1. Complex formation was required for maintaining normal azole susceptibility. Scarv1 cells expressing orthologous CaArv1 mutants also had reduced CaErg11 levels, were unable to form a CaArv1-CaErg11 complex, and were azole hypersusceptible. Scarv1 cells expressing CaArv1 mutants unable to interact with CaErg11 could not sustain proper levels of the azole resistant CaErg11Y132F F145L protein. Caarv1/Caarv1 cells expressing CaArv1 mutants unable to interact with CaErg11 were found to lack virulence using a disseminated candidiasis mouse model. Expressing CaErg11Y132F F145L did not reverse the lack of virulence. We hypothesize that the role of Arv1 in Erg11-dependent azole resistance is to stabilize Erg11 protein level. Arv1 inhibition may represent an avenue for treating azole resistance.
Insights
Arv1 protein is crucial for maintaining azole antifungal susceptibility by stabilizing Erg11, a key enzyme in fungal sterol biosynthesis. Inhibiting Arv1 may offer a new strategy to combat azole-resistant fungal infections.
Area of Science:
- Biochemistry
- Mycology
- Drug Discovery
Background:
- Azole-resistant fungal infections pose a significant threat, particularly to immunocompromised individuals.
- Existing antifungal therapies face limitations due to emerging resistance mechanisms.
- Identifying novel drug targets is essential for developing new therapeutics against resistant fungi.
Purpose of the Study:
- To investigate the structure-function relationship of Arv1 (are1 are2 required for viability 1) in azole susceptibility.
- To elucidate the molecular mechanism by which Arv1 influences the activity of Erg11 (lanosterol 14-α-demethylase), the target of azole antifungals.
- To explore Arv1 as a potential therapeutic target for overcoming azole resistance.
Main Methods:
- Structure-function analysis of Saccharomyces cerevisiae Arv1 (ScArv1) mutants.
- Assessing azole susceptibility in yeast strains expressing wild-type and mutant Arv1 proteins.
- Quantifying Erg11 protein levels and evaluating its stability in the presence of Arv1 mutants.
- Investigating the interaction between Arv1 and Erg11 through complex formation studies.
- Evaluating the virulence of Candida albicans strains with altered Arv1 function in a mouse model.
Main Results:
- Specific ScArv1 mutants were unable to restore normal azole susceptibility and showed reduced Erg11 protein levels.
- Erg11 protein stability was dependent on its heterodimeric complex formation with Arv1, which was essential for azole susceptibility.
- Candida albicans strains expressing non-interacting Arv1 mutants exhibited reduced Erg11 levels, impaired complex formation, and hypersusceptibility to azoles.
- These Arv1 mutants also led to a lack of virulence in a disseminated candidiasis mouse model.
- Arv1 inhibition may represent a novel strategy for treating azole-resistant fungal infections.
Conclusions:
- Arv1 plays a critical role in maintaining azole antifungal resistance by stabilizing Erg11 protein levels.
- The interaction between Arv1 and Erg11 is essential for Erg11 stability and azole susceptibility.
- Arv1's function in Erg11 stabilization highlights its potential as a therapeutic target for combating azole-resistant fungal infections.
