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polysulfide reductase beta (PsrB) subunit This family includes the beta subunit of bacterial polysulfide reductase (PsrABC), an integral membrane-bound enzyme responsible for quinone-coupled reduction of polysulfides, a process important in extreme environments such as deep-sea vents and hot springs. Polysulfide reductase contains three subunits: a catalytic subunit PsrA, an electron transfer PsrB subunit and the hydrophobic transmembrane PsrC subunit. PsrB belongs to the DMSO reductase superfamily that contains [4Fe-4S] clusters which transfer the electrons from the A subunit to the hydrophobic integral membrane C subunit via the B subunit. In Shewanella oneidensis, which has highly diverse anaerobic respiratory pathways, PsrABC is responsible for H2S generation as well as its regulation via respiration of sulfur species. PsrB transfers electrons from PsrC (serving as quinol oxidase) to the catalytic subunit PsrA for reduction of corresponding electron acceptors. It has been shown that T. thermophilus polysulfide reductase could be a key energy-conserving enzyme of the respiratory chain, using polysulfide as the terminal electron acceptor and pumping protons across the membrane. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",