Deciphering the Role of Multiple Thioredoxin Fold Proteins of Leptospirillum sp. in Oxidative Stress Tolerance.

Daniela González,Renato Chávez,Omar Orellana,Gloria Levicán,Pamela Álamos,Javiera Norambuena,Matías Rivero

doi:10.3390/ijms21051880

Abstract

Thioredoxin fold proteins (TFPs) form a family of diverse proteins involved in thiol/disulfide exchange in cells from all domains of life. Leptospirillum spp. are bioleaching bacteria naturally exposed to extreme conditions like acidic pH and high concentrations of metals that can contribute to the generation of reactive oxygen species (ROS) and consequently the induction of thiol oxidative damage. Bioinformatic studies have predicted 13 genes that encode for TFP proteins in Leptospirillum spp. We analyzed the participation of individual tfp genes from Leptospirillum sp. CF-1 in the response to oxidative conditions. Genomic context analysis predicted the involvement of these genes in the general thiol-reducing system, cofactor biosynthesis, carbon fixation, cytochrome c biogenesis, signal transduction, and pilus and fimbria assembly. All tfp genes identified were transcriptionally active, although they responded differentially to ferric sulfate and diamide stress. Some of these genes confer oxidative protection to a thioredoxin-deficient Escherichia coli strain by restoring the wild-type phenotype under oxidative stress conditions. These findings contribute to our understanding of the diversity and complexity of thiol/disulfide systems, and of adaptations that emerge in acidophilic microorganisms that allow them to thrive in highly oxidative environments. These findings also give new insights into the physiology of these microorganisms during industrial bioleaching operations.

Highlights

Thioredoxin (TRX) fold proteins (TFP) are a family of diverse proteins that possess a common domain consisting of four stranded beta-sheets flanked by three alpha-helices, and the redox-active CXXC motif [1]
A previous study demonstrated that the strain Leptospirillum sp
The genes for the 13 predicted Thioredoxin fold proteins (TFPs) from the 5-way CG strain were detected in the genome of strain CF-1, and these predicted proteins were characterized bioinformatically

Summary

Introduction

Thioredoxin (TRX) fold proteins (TFP) are a family of diverse proteins that possess a common domain consisting of four stranded beta-sheets flanked by three alpha-helices, and the redox-active CXXC motif [1]. The most representative member of this family is thioredoxin, a small disulfide reductase that helps to maintain a reducing cytosolic environment through reduction of oxidized thiols in cytoplasmic proteins [2]. Many of these proteins are involved in thiol/disulfide exchange reactions, and in oxidation and reduction reactions, depending on their redox properties. They play pivotal roles in protein folding and redox control in a number of biological processes. The role of these proteins cannot be directly deduced by the mere identification of a thioredoxin fold as structural feature

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