Identification and functional characterization of a novel thioredoxin MpTRX1 from Metschnikowia persimmonesis

Abstract

Thioredoxins (TRXs) are small, conserved redox-active proteins that play central roles in oxidative stress responses. Here, we identified and functionally characterized a novel thioredoxin, MpTRX1, from the newly isolated yeast Metschnikowia persimmonesis. The full-length MpTRX1 gene was cloned and expressed in Escherichia coli and Saccharomyces cerevisiae to analyze its biochemical and physiological functions. MpTRX1 encodes a 103-amino-acid protein containing a canonical CXXC redox motif, and structural modeling confirmed a conserved thioredoxin fold. Recombinant MpTRX1 exhibited clear disulfide reductase activity in both DTNB (5,5 '-dithiobis-(2-nitrobenzoic acid)) and insulin reduction assays. Mutation of either catalytic cysteine residue abolished activity, confirming their essential roles. Moreover, heterologous expression of MpTRX1 in S. cerevisiae enhanced tolerance to hydrogen-peroxide-induced oxidative stress. Although the functional assays were conducted in a heterologous system, these findings demonstrate that MpTRX1 is a bona fide thioredoxin that may contribute to oxidative stress protection in M. persimmonesis. This work provides the first molecular characterization of a protein from M. persimmonesis and establishes a foundation for future studies on its potential ecological and biotechnological applications.Key points center dot Identification of MpTRX1, a novel thioredoxin from M. persimmonesis.center dot Recombinant MpTRX1 reduces both chemical and protein substrates.center dot Overexpression of MpTRX1 enhances oxidative stress tolerance in S. cerevisiae.Key points center dot Identification of MpTRX1, a novel thioredoxin from M. persimmonesis.center dot Recombinant MpTRX1 reduces both chemical and protein substrates.center dot Overexpression of MpTRX1 enhances oxidative stress tolerance in S. cerevisiae.Key points center dot Identification of MpTRX1, a novel thioredoxin from M. persimmonesis.center dot Recombinant MpTRX1 reduces both chemical and protein substrates.center dot Overexpression of MpTRX1 enhances oxidative stress tolerance in S. cerevisiae.