Analysis of a ufdB Penicillium marneffei Mutant Generated by Agrobacterium tumefaciens-Mediated Transformation

Abstract

Penicillium marneffei is a notorious, medically pertinent fungal pathogen responsible for causing penicilliosis within immunocompromised individuals, particularly those with HIV/AIDS. Existing as a mold at 25°C and yeast at 37°C, it is the only Penicillium species known to undergo a temperature-dependent dimorphic switch. Recently, Agrobacterium tumefaciens-mediated transformation (ATMT) was used to introduce randomly integrated T-DNA fragments into the P. marneffei genome. This study sought to genotypically and phenotypically characterize mutant I189. An inverse PCR protocol was employed to recover the DNA sequences flanking the T-DNA insertion site. BLAST analysis revealed an interruption of a putative ubiquitin fusion degradation protein (UfdB) mRNA. Orthologous in the human pathogen Aspergillus fumigatus as well as model yeasts Schizosaccharomyces pombe and Saccharomyces cerevisiae, this protein has been documented to tag abnormal stress-induced proteins for degradation. Current investigations of ufdB in P. marneffei mutant I189 show that fungal growth is significantly diminished in the presence of nutrient limitation although a full mRNA transcript is being produced. However, exposure to Congo Red, sodium dodecyl sulfate (SDS), and heat stress had no effect on cell viability.