AUTHOR=Wu Genfu , Li Ning , Mao Yinting , Zhou Guangqi , Gao Haichun 

TITLE=Endogenous generation of hydrogen sulfide and its regulation in Shewanella oneidensis

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00374

DOI=10.3389/fmicb.2015.00374

ISSN=1664-302X

ABSTRACT=<p>Hydrogen sulfide (H<sub>2</sub>S) has been recognized as a physiological mediator with a variety of functions across all domains of life. In this study, mechanisms of endogenous H<sub>2</sub>S generation in <italic>Shewanella oneidensis</italic> were investigated. As a research model with highly diverse anaerobic respiratory pathways, the microorganism is able to produce H<sub>2</sub>S by respiring on a variety of sulfur-containing compounds with SirACD and PsrABC enzymatic complexes, as well as through cysteine degradation with three enzymes, MdeA, SO_1095, and SseA. We showed that the SirACD and PsrABC complexes, which are predominantly, if not exclusively, responsible for H<sub>2</sub>S generation via respiration of sulfur species, do not interplay with each other. Strikingly, a screen for regulators controlling endogenous H<sub>2</sub>S generation by transposon mutagenesis identified global regulator Crp to be essential to all H<sub>2</sub>S-generating processes. In contrast, Fnr and Arc, two other global regulators that have a role in respiration, are dispensable in regulating H<sub>2</sub>S generation via respiration of sulfur species. Interestingly, Arc is involved in the H<sub>2</sub>S generation through cysteine degradation by repressing expression of the <italic>mdeA</italic> gene. We further showed that expression of the <italic>sirA</italic> and <italic>psrABC</italic> operons is subjected to direct regulation of Crp, but the mechanisms underlying the requirement of Crp for H<sub>2</sub>S generation through cysteine degradation remain elusive.</p>