Molecular cloning, expression and insulin reduction activity of a thioredoxin 1 homologue (TRX1) from the pathogenic fungus Paracoccidioides lutzii.

The dimorphic fungi Paracoccidioides spp. are the etiological agents of paracoccidioidomycosis (PCM), a prevalent systemic mycosis in Latin America. The Paracoccidioides lutzii response to oxidative stress is largely unexplored. Thioredoxins (TRX) are involved in the regulation of the redox environment in the cell, responding to oxidative stress in several organisms. In this study, we describe the isolation and characterization of a cDNA encoding a thioredoxin 1 from yeast cells from P. lutzii. The cDNA codes for a 12kDa protein containing the characteristic thioredoxin active site. The thioredoxin 1 gene was expressed in Escherichia coli and the isolated thioredoxin 1 recombinant protein as the native PlTRX1 from yeast cells showed insulin reduction activity in vitro. We also showed by semi-quantitative RT-PCR analysis that the expression of thioredoxin 1 gene was induced in response to H2 O2 and may exert an antioxidant activity in vivo. Our results suggest that the thioredoxin 1 may play an important role in controlling the redox status in P. lutzii which may contribute to this organism's virulence.