Members of the phylum Campylobacterota, which dominate deep-sea hydrothermal vent ecosystems, typically harbor the ability for thiosulfate oxidation through a complete sulfur oxidation (Sox) system encoded by the soxABXY 1 Z 1 and soxCDY 2 Z 2 gene clusters. Bioinformatic analysis identified a two-component regulatory system (TCS) SulRS in Sulfurimonas hydrogeniphila, a representative member of Campylobacterota. EMSA and DNase Ⅰ footprinting assays confirmed that SulR specifically binds to promoters Px, Py, and Pr, and its Px-binding sequence contains two conserved direct repeat sequences. Combined microscale thermophoresis (MST) and dual-plasmid reporter assays showed that SulS can senses thiosulfate signals and activates soxABXY 1 Z 1 transcription, whereas this substrate exerts no significant effect on soxCDY 2 Z 2 transcription. Genomic analysis further revealed that sulRS-soxABXY 1 Z 1 -like gene clusters are widely conserved among sulfur-oxidizing bacteria within Campylobacterota. These findings suggest that the SulRS may play a pivotal role in regulating sulfur oxidation, likely facilitating the response, adaptation, and survival of these bacteria in chemosynthetic environments rich in reduced sulfur compounds.
Zhong et al. (Wed,) studied this question.