Environmental polysulfides promote protein disulfide bond formation of microorganisms growing under anaerobic condition

Abstract

Polysulfides are rich in anaerobic and microbial metabolism active environments. Anaerobic survival of microorganisms requires the formation of protein disulfide bond (DSB). The relation between environmental polysulfides and anaerobic DSB formation has not been studied so far. Herein, we discovered that environmental polysulfides can efficiently mediate protein DSB formation of microorganisms under anaerobic condition. We used polysulfides to treat proteins including roGFP2, Trx1, and DsbA under anaerobic condition and found that all three proteins formed intramolecular DSB in vitro. The growth of E. coli ΔdsbB was reduced and the amount of its intracellular protein DSB was decreased under anaerobic condition. However, treating the mutant strain with polysulfides recovered the growth and reversed DSB decrease. Treating E. coli ΔdsbA with polysulfides promoted DSB formation of its periplasmic roGFP2 and recovered its growth under anaerobic condition. In addition, treating Schizosaccharomyces pombe with polysulfides led to increase of the intracellular protein DSB content. Thus, our study reveals that environmental polysulfides can promote DSB formation independent of the enzymatic DSB mediating system and oxygen. In this aspect, environmental polysulfides are beneficial for the survival of microorganisms in anaerobic habitats.