Hube B, Hess D, Baker CA, Schaller M, Schäfer W, Dolan JW (2001): The role and relevance of phospholipase D1 during growth and dimorphism of Candida albicans
Microbiology 147: 879-889.

The phosphatidylcholine-specific phospholipase D1 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 RT-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 (PA), the hydrolytic product of PLD1 activity, and strongly reduced levels of diacylglycerol (DAG), 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 temperature of growth. In addition, growth rates of pld1 mutants in media with protein as the sole source of nitrogen was 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 attenuated virulence properties. In contrast, the mutant was less virulent in two different mouse models. These data suggest that PLD1 is not essential for growth and oral infections. However, they also suggests that a prominent part of the PA and DAG pools is produced by PLD1 and that the level of these components is important for morphological transitions under certain conditions in C. albicans.