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K143R Amino Acid Substitution in 14-α-Demethylase (Erg11p) Changes Plasma Membrane and Cell Wall Structure of Candida
Daria Derkacz1, Przemysław Bernat2, Anna Krasowska1
1Department of Biotransformation, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland.
Abstract:
The opportunistic pathogen Candida albicans is responsible for life-threating infections in immunocompromised individuals. Azoles and polyenes are two of the most commonly used antifungals and target the ergosterol biosynthesis pathway or ergosterol itself. A limited number of clinically employed antifungals correspond to the development of resistance mechanisms. One resistance mechanism observed in clinical isolates of azole-resistant C. albicans is the introduction of point mutations in the ERG11 gene, which encodes a key enzyme (lanosterol 14-α-demethylase) on the ergosterol biosynthesis pathway. Here, we demonstrate that a point mutation K143R in ERG11 (C. albicans ERG11K143R/K143R) contributes not only to azole resistance, but causes increased gene expression. Overexpression of ERG11 results in increased ergosterol content and a significant reduction in plasma membrane fluidity. Simultaneously, the same point mutation caused cell wall remodeling. This could be facilitated by the unmasking of chitin and β-glucan on the fungal cell surface, which can lead to recognition of the highly immunogenic β-glucan, triggering a stronger immunological reaction. For the first time, we report that a frequently occurring azole-resistance strategy makes C. albicans less susceptible to azole treatment while, at the same time, affects its cell wall architecture, potentially leading to exposure of the pathogen to a more effective host immune response.
Insights
A common azole resistance mechanism in Candida albicans involves a mutation in the ERG11 gene. This mutation not only confers drug resistance but also alters the fungal cell wall, potentially enhancing immune responses.
Area of Science:
- Mycology
- Immunology
- Molecular Biology
Background:
- * *Candida albicans* is an opportunistic pathogen causing severe infections in immunocompromised individuals.
- * Azoles and polyenes are primary antifungal drugs targeting ergosterol biosynthesis or ergosterol.
- * Antifungal resistance, particularly to azoles, is a growing clinical concern.
Purpose of the Study:
- * To investigate the impact of the K143R point mutation in the *ERG11* gene on *Candida albicans* azole resistance and cellular properties.
- * To explore how this mutation affects ergosterol content, membrane fluidity, and cell wall structure.
- * To determine if the mutation influences the host immune response.
Main Methods:
- * Genetic manipulation to create *C. albicans* with the *ERG11*K143R/K143R genotype.
- * Measurement of *ERG11* gene expression levels.
- * Analysis of ergosterol content and plasma membrane fluidity.
- * Assessment of cell wall composition and surface exposure of chitin and β-glucan.
Main Results:
- * The K143R mutation in *ERG11* confers azole resistance and increases *ERG11* gene expression.
- * Overexpression of *ERG11* leads to higher ergosterol levels and reduced plasma membrane fluidity.
- * The mutation induces cell wall remodeling, potentially exposing immunogenic components like β-glucan.
Conclusions:
- * The K143R mutation in *ERG11* is a significant azole resistance strategy in *C. albicans*.
- * This mutation alters fungal cell wall architecture, potentially increasing susceptibility to host immune responses.
- * Findings highlight a dual effect of resistance mechanisms: reduced drug efficacy and altered host-pathogen interaction.
