Phenotypic Characterization and Gene Expression Analyses of a Penicillium marneffei Septin Mutant

Abstract

Penicillium marneffei is the only known thermally dimorphic species of the Penicillium genus, growing as a filamentous mold at 25°C and adopting yeast morphology at 37°C. Endemic to Southeast Asia, there is no known reservoir for P. marneffei. Nonetheless, the evolutionary adaptation of phase transition has allowed P. marneffei to become a highly aggressive, opportunistic pathogen. Since the emergence of AIDS, P. marneffei infections have become increasingly common due to its increased virulence when invading immunocompromised individuals with most cases being reported in Thailand. Phase transition in P. marneffei is tightly regulated at the transcriptional level. Gene expression in P. marneffei is regulated when subjected to higher or lower temperatures. These thermally dependent, phase specific regulatory mechanisms are of current interest, as understanding such mechanisms will potentially provide targets for chemotherapeutic agents in treating P. marneffei infections in the future. Presently, an Agrobacterium tumefaciens-mediated transformation (AMT)-generated mutant in septin function is being studied in order to establish its role in phase transition and normal vegetative growth. Preliminary results indicate that the disruption mutation in the aspC gene caused aberrant morphological characteristics. In addition, aspC expression in the aspC mutant was greater than that in the wild-type strain.