Characterization of the Type III sulfide:quinone oxidoreductase from Caldivirga maquilingensis and its membrane binding

► The sulfide:quinone oxidoreductase (SQR) from C. maquilingensis was characterized. ► This is the first representative of a “Class III” SQR to be characterized. ► Membrane binding is mediated by residues in the C-terminal amphiphilic helix. ► Mutations in this portion of the protein convert the enzyme to a soluble form.