OxyR senses reactive sulfane sulfur and activates genes for its removal in Escherichia coli

Abstract

20Reactive sulfane sulfur species such as hydrogen polysulfide and organic persulfide 21 are newly recognized as normal cellular components, involved in signaling and 22 protecting cells from oxidative stress. Their production is extensively studied, but 23 their removal is less characterized. Herein, we showed that reactive sulfane sulfur is 24 toxic at high levels, and it is mainly removed via reduction by thioredoxin and 25 glutaredoxin with the release of H 2 S in Escherichia coli. OxyR is best known to 26 respond to H 2 O 2 , and it also played an important role in responding to reactive sulfane 27 sulfur under both aerobic and anaerobic conditions. It was modified by hydrogen 28 polysulfide to OxyR C199-SSH, which activated the expression of thioredoxin 2 and 29 glutaredoxin 1. This is a new type of OxyR modification. Bioinformatics analysis 30 showed that OxyRs are widely present in bacteria, including strict anaerobic bacteria. 31Thus, the OxyR sensing of reactive sulfane sulfur may represent a conserved 32 mechanism for bacteria to deal with sulfane sulfur stress. 33 34