<i>CRZ1</i> , a target of the calcineurin pathway in <i>Candida albicans</i>

<jats:title>Summary</jats:title> <jats:p> Calcineurin is a major player in calcium‐dependent signal transduction pathways of eukaryotes. Calcineurin acts on transcription factors (e.g. <jats:italic>CRZ1</jats:italic> in <jats:italic>Saccharomyces cerevisiae</jats:italic> ) and governs the expression of genes in a species‐dependent fashion. In <jats:italic>Candida albicans</jats:italic> , the calcineurin pathway is involved in tolerance to antifungal agents, cation homeostasis and virulence. However, the components of the calcineurin pathway are still poorly investigated in this yeast species. Taking <jats:italic>S. cerevisiae</jats:italic> as a model to reconstitute this pathway, two <jats:italic>CRZ1</jats:italic> ‐like genes, <jats:italic>CRZ1</jats:italic> and <jats:italic>CRZ2</jats:italic> (for <jats:styled-content>c</jats:styled-content> alcineurin‐ <jats:styled-content>r</jats:styled-content> esponsive <jats:styled-content>z</jats:styled-content> inc finger 1 and 2 genes), were found with C <jats:sub>2</jats:sub> H <jats:sub>2</jats:sub> zinc finger domains. Only <jats:italic>CRZ1</jats:italic> was able to restore the calcium hypersusceptibility of a <jats:italic>S. cerevisiae crz1</jats:italic> Δ mutant and to mediate calcium‐dependent gene expression in this yeast species. Several experiments showed that <jats:italic>CRZ1</jats:italic> was dependent on calcineurin in <jats:italic>C. albicans</jats:italic> : (i) phenotypic analysis of a <jats:italic>crz1</jats:italic> Δ/Δ mutant showed impaired growth as compared with the wild type in the presence of cations (Ca <jats:sup>2+</jats:sup> , Mn <jats:sup>2+</jats:sup> ) as does a mutant lacking calcineurin subunit A ( <jats:italic>cna</jats:italic> Δ/Δ) and (ii) a green fluorescent protein (GFP)–Crz1p fusion protein showed a calcium‐ and calcineurin‐dependent nuclear localization. To further analyse the relationship between calcineurin and <jats:italic>CRZ1</jats:italic> , a comprehensive analysis of calcineurin/Crz1p‐dependent gene expression following addition of Ca <jats:sup>2+</jats:sup> (200 mM) was performed. Among the expression of 264 genes altered by at least twofold, the upregulation of 60 genes was dependent on both calcineurin and <jats:italic>CRZ1</jats:italic> . Interestingly, a motif [5′‐G(C/T)GGT‐3′] with similarity to the target sequence of Crz1p (GNGGCG/TCA) from <jats:italic>S. cerevisiae</jats:italic> was identified as a putative regulatory sequence in the upstream regions of these calcineurin/Crz1p‐dependent genes. However, additional experiments showed that calcineurin may have other targets in addition to <jats:italic>CRZ1</jats:italic> . First, <jats:italic>CRZ1</jats:italic> was not involved in tolerance to antifungal agents (fluconazole, terbinafine) on the opposite to calcineurin. Second, <jats:italic>CRZ1</jats:italic> was only moderately influencing virulence in a mice model of infection which is in sharp contrast to the strong avirulence of <jats:italic>cna</jats:italic> Δ/Δ mutant in the same animal model. Even though this work establishes <jats:italic>CRZ1</jats:italic> as a calcineurin target, further studies are needed to identify other calcineurin‐dependent elements in <jats:italic>C. albicans</jats:italic> . </jats:p>