Isolation and Differential Expression of ura5 Gene during Phase Transition and Stress Conditions in a Human Pathogenic Dimorphic Fungus, Penicillium marneffei

Abstract

Penicillium marneffei, a dimorphic fungus, can cause an opportunistic infection in immunocompromised patients especially in AIDS patients. Molecular genetic studies of P. marneffei provide more understanding about the mechanism of fungal pathogenesis. We have isolated and characterized the ura5 gene, which encodes orotate phosphoribosyltransferase (OPRTase), from P. marneffei. The nucleotide and amino acid sequences of ura5 displayed strong homology to OPRTase proteins in other fungi. Analysis of the ura5 gene expression by RT-PCR revealed that the expression was upregulated at an early step during mycelium to yeast phase transition, and substantially upregulated in mycelial cells exposed to 39oC or treated with 1 mM of H2O2 for 30 min. The results suggested that the ura5 gene might play some role on the thermal adaptation of P. marneffei during temperature-induced yeast phase transition and stress conditions.