The human oportunistic pathogen Penicillium marneffei is a thermally dimorphic fungus. The saprofitic form is filamentous in growth at 25 ºC, resembling other Penicillium species. The pathogenic form is an unicellular yeast at 37 ºC, which divides by fission. To cope with nutrient deprivation during the infection process, a number of fungi employ the glyoxylate bypass. Therefore, enzymes belonging to this pathway have been implicated in pathogenesis. The glyoxylate bypass is required to replanish TCA cycle intermediates during growth on gluconeogenic carbon sources. P. marneffei can utilise a variety of carbon sources, including acetate and fatty acids. To gain insight into the organism's ability to utilise these carbon sources during its pathogenic process, we studied one of the key enzymes and a regulator of the glyoxylate cycle. acuD (isocitrate lyase) is required for growth in both acetate and fatty acids. In yeasts and Aspergillus nidulans, induction of acuD is dependent on carbon source. Surprisingly, acuD is mainly regulated by temperature in P. marneffei, being strongly induced at 37 ºC (body temperature) even in the presence of glucose and weakly induced at 25 ºC only when acetate is present. A major Zn(II)2Cys6 regulator of isocitrate lyases in other fungi was also cloned and examined in P. marneffei.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)