1. Zap1 control of cell-cell signaling in Candida albicans biofilms.
- Author
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Ganguly S, Bishop AC, Xu W, Ghosh S, Nickerson KW, Lanni F, Patton-Vogt J, and Mitchell AP
- Subjects
- Candida albicans drug effects, Candida albicans genetics, Candida albicans metabolism, Cation Transport Proteins biosynthesis, Farnesol analysis, Farnesol metabolism, Farnesol pharmacology, Fungal Proteins biosynthesis, Fungal Proteins genetics, Gas Chromatography-Mass Spectrometry, Gene Expression Regulation, Fungal drug effects, Hyphae genetics, Hyphae metabolism, Membrane Glycoproteins biosynthesis, Quorum Sensing drug effects, Quorum Sensing genetics, Biofilms growth & development, Candida albicans physiology, Fungal Proteins metabolism, Signal Transduction
- Abstract
Biofilms of Candida albicans include both yeast cells and hyphae. Prior studies indicated that a zap1Δ/Δ mutant, defective in zinc regulator Zap1, has increased accumulation of yeast cells in biofilms. This altered yeast-hypha balance may arise from internal regulatory alterations or from an effect on the production of diffusible quorum-sensing (QS) molecules. Here, we develop biosensor reporter strains that express yeast-specific YWP1-RFP or hypha-specific HWP1-RFP, along with a constitutive TDH3-GFP normalization standard. Seeding these biosensor strains into biofilms allows a biological activity assay of the surrounding biofilm milieu. A zap1Δ/Δ biofilm induces the yeast-specific YWP1-RFP reporter in a wild-type biosensor strain, as determined by both quantitative reverse transcription-PCR (qRT-PCR) gene expression measurements and confocal microscopy. Remediation of the zap1Δ/Δ zinc uptake defect through zinc transporter gene ZRT2 overexpression reverses induction of the yeast-specific YWP1-RFP reporter. Gas chromatography-mass spectrometry (GC-MS) measurements of known organic QS molecules show that the zap1Δ/Δ mutant accumulates significantly less farnesol than wild-type or complemented strains and that ZRT2 overexpression does not affect farnesol accumulation. Farnesol is a well-characterized inhibitor of hypha formation; hence, a reduction in farnesol levels in zap1Δ/Δ biofilms is unexpected. Our findings argue that a Zap1- and zinc-dependent signal affects the yeast-hypha balance and that it is operative in the low-farnesol environment of the zap1Δ/Δ biofilm. In addition, our results indicate that Zap1 is a positive regulator of farnesol accumulation.
- Published
- 2011
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