Eukaryotic Cell doi:10.1128/EC.00155-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.
Pseudohyphal development, stress adaptation and drug sensitivity of the opportunistic yeast Candida lusitaniae: differential involvement of histidine kinase receptors
Florence Chapeland-Leclerc*,
Paméla Paccallet,
Gwenaël Ruprich-Robert,
David Reboutier,
Christiane Chastin,
and
Nicolas Papon
Programme Chimiorésistance des Levures Pathogènes, EA209 « Eucaryotes Pathogènes : Transports Membranaires et Chimiorésistance », UFR des Sciences Pharmaceutiques et Biologiques, Université Paris-Descartes, 75006 Paris, France
* To whom correspondence should be addressed. Email:
florence.leclerc{at}univ-paris5.fr.
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Abstract |
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Fungal histidine kinase receptors (HKRs) sense and transduce many extracellular signals. We investigated the role of HKRs in the morphogenetic transition, osmotolerance, oxidative stress response and mating ability in the opportunistic yeast Candida lusitaniae. We isolated three genes, SLN1, NIK1 and CHK1, potentially encoding HKRs of class VI, III and X, respectively. These genes were disrupted by a transformation system based upon the "URA3-blaster" strategy. Functional analysis of disruptants was undertaken, except for the double mutant sln1 nik1 and the triple mutant sln1 nik1 chk1 which are not viable in C. lusitaniae. The sln1 mutant revealed a high sensitivity to oxidative stress whereas both nik1 and chk1 mutants exhibited a more moderate sensitivity to peroxyde. We also showed that the NIK1 gene was implicated in phenylpyrrole and dicarboximide compounds susceptibility while HKRs seem not to be involved in resistance toward antifungals of clinical relevance. Concerning mating ability, all disruptants were still able to reproduce sexually in vitro in unilateral or bilateral crosses. The most important result of this study was that the sln1 mutant displayed a global defect of pseudohyphal differentiation, especially in high osmolarity and oxidative stress conditions. Thus, the SLN1 gene could be crucial for the C. lusitaniae yeast to pseudohyphae morphogenetic transition. This implication is strengthened by a high level of SLN1 mRNAs revealed by semi-quantitative RT-PCR when the yeast develops pseudohyphae. Our findings highlight a differential contribution of the three HKRs in osmotic and oxidant adaptation during the morphological transition in C. lusitaniae.
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