Properties of a Wolinella succinogenes mutant lacking periplasmic sulfide dehydrogenase (Sud).

A delta sud deletion mutant of Wolinella succinogenes that lacked the periplasmic sulfide dehydrogenase (Sud) was constructed using homologous recombination. The mutant grew with sulfide and fumarate, indicating that Sud was not a component of the electron transport chain that catalyzed fumarate respiration with sulfide as an electron donor. Likewise, growth with formate and either polysulfide or sulfur was not affected by the deletion. Removal of Sud from wild-type W. succinogenes by spheroplast formation did not decrease the activity of electron transport to polysulfide. The delta psr deletion mutant that lacks polysulfide reductase (Psr) grew by fumarate respiration with sulfide as an electron donor, indicating that Psr is not required for this activity.

Periplasmic sulphide dehydrogenase (Sud) from Wolinella succinogenes: isolation, nucleotide sequence of the sud gene and its expression in Escherichia coli.

Wolinella succinogenes contains a periplasmic sulphide dehydrogenase when grown with formate and polysulphide as catabolic substrates. The isolated enzyme catalyzes the reduction of dimethylnaphthoquinone with sulphide at high values of both apparent Km and turnover number. The active enzyme consists of two identical subunits (14 kDa) and amounts to approximately 1% of the soluble cell protein. Prosthetic groups such as flavin, haem or molybdenum are missing. The corresponding gene (sud) encodes a signal peptide together with the mature subunit that consists of 129 amino acid residues including one single cysteine. The sud gene is expressed from a plasmid in Escherichia coli. The resulting enzyme catalyzes sulphide oxidation with dimethylnaphthoquinone and is located in the periplasm of E. coli.