The role and relevance of phospholipase D1 during growth and dimorphism of Candida albicans

• Published in: Microbiology (Society for General Microbiology) 2001-04, Vol.147 (4), p.879-889
• Main Authors: Hube, Bernhard, Hess, Daniela, Baker, Carol A, Schaller, Martin, Schafer, Wilhelm, Dolan, Joseph W
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Blotting, Northern; Blotting, Southern; Candida albicans; Candida albicans - growth & development; Candida albicans - metabolism; Candida albicans - physiology; Candidiasis - enzymology; Culture Media; Diacylglycerol; Fundamental and applied biological sciences. Psychology; Genes, Fungal; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; In Vitro Techniques; Mice; Mice, Nude; Microbiology; Mutagenesis, Site-Directed; Mycology; Phenotype; Phosphatidic acid; Phospholipase D - genetics; Phospholipase D - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Sequence Deletion; Spores, Fungal - growth & development; Spores, Fungal - physiology; Virulence
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-147-4-879

Institut für Allgemeine Botanik, AMP III, Universität Hamburg, Ohnhorststr. 18, D-22609 Hamburg, Germany 1 Medical University of South Carolina, Department of Microbiology and Immunology, PO Box 250504, Charleston, SC 29425, USA 2 Robert Koch-Institut, NG4, Nordufer 20, D-13353 Berlin, Germany 3 Dermatologische Klinik und Poliklinik der Ludwig-Maximilians-Universität München, Frauenlobstr.9-11, D-80337 München, Germany 4 Author for correspondence: Bernhard Hube. Tel: [phone]. Fax: [phone]. e-mail: HubeB{at}rki.de The phosphatidylcholine-specific phospholipase D1 (PLD1) in Saccharomyces cerevisiae is involved in vesicle transport and is essential for sporulation. The gene encoding the homologous phospholipase D1 from Candida albicans ( PLD1 ) was used to study the role of PLD1 in this pathogenic fungus. In vitro and in vivo expression studies using Northern blots and reverse transcriptase-PCR showed low PLD1 mRNA levels in defined media supporting yeast growth and during experimental infection, while enhanced levels of PLD1 transcripts were detected during the yeast to hyphal transition. To study the relevance of PLD1 during yeast and hyphal growth, an essential part of the gene was deleted in both alleles of two isogenic strains. In vitro PLD1 activity assays showed that pld1 mutants produced no detectable levels of phosphatidic acid, the hydrolytic product of PLD1 activity, and strongly reduced levels of diacylglycerol, the product of lipid phosphate phosphohydrolase, suggesting no or a negligible background PLD1 activity in the pld1 mutants. The pld1 mutants showed no growth differences compared to the parental wild-type in liquid complex and minimal media, independent of the growth temperature. In addition, growth rates of pld1 mutants in media with protein as the sole source of nitrogen were similar to growth rates of the wild-type, indicating that secretion of proteinases was not reduced. Chlamydospore formation was normal in pld1 mutants. When germ tube formation was induced in liquid media, pld1 mutants showed similar rates of yeast to hyphal transition compared to the wild-type. However, no hyphae formation was observed on solid Spider medium, and cell growth on cornmeal/Tween 80 medium indicated aberrant morphogenesis. In addition, pld1 mutants growing on solid media had an attenuated ability to invade the agar. In a model of oral candidosis, pld1 mutants showed no attenuation of virulence. In contrast, the mutant was less vi