A Molybdopterin Oxidoreductase Is Involved in H2 Oxidation in Desulfovibrio desulfuricans G20

摘要

Three mutants deficient in hydrogen/formate uptake were obtained through screening of a transposon mutant library containing 5,760 mutants of Desulfovibrio desulfuricans G20. Mutations were in the genes encoding the type I tetraheme cytochrome c₃ (cycA), Fe hydrogenase (hydB), and molybdopterin oxidoreductase (mopB). Mutations did not decrease the ability of cells to produce H₂ or formate during growth. Complementation of the cycA and mopB mutants with a plasmid carrying the intact cycA and/or mopB gene and the putative promoter from the parental strain allowed the recovery of H₂ uptake ability, showing that these specific genes are involved in H₂ oxidation. The mop operon encodes a periplasm-facing transmembrane protein complex which may shuttle electrons from periplasmic cytochrome c₃ to the menaquinone pool. Electrons can then be used for sulfate reduction in the cytoplasm.