Disease relevance of HYPD

• The cytochrome b subunit (HydC) of Wolinella succinogenes hydrogenase binds two haem B groups [1].
• The nucleotide sequence of a 2.2 kb region downstream of the hydrogenase structural genes in Bradyrhizobium japonicum was determined [2].
• HupC is homologous to the hydrophobic polypeptides with four potential transmembrane regions that are encoded by open reading frames following the hydrogenase structural genes in Rhodobacter capsulatus, Escherichia coli, Azotobacter vinelandii, Wolinella succinogenes, Rhizobium leguminosarum and Alcaligenes eutrophus [2].
• Hydrogenase from Vibrio succinogenes, a nickel protein [3].
• Diphenylene iodonium as an inhibitor for the hydrogenase complex of Rhodobacter capsulatus. Evidence for two distinct electron donor sites [4].

High impact information on HYPD

• Substitution in HydC of His-25, His-67 or His-186, which are, in addition to His-200, predicted to be haem B ligands, caused the loss of quinone reactivity of the hydrogenase, while the activity of benzylviologen reduction was retained [1].
• Identification of histidine residues in Wolinella succinogenes hydrogenase that are essential for menaquinone reduction by H2 [1].
• The electron transport chain is made up of two dehydrogenases (hydrogenase and formate dehydrogenase) that catalyze the reduction of menaquinone, and fumarate reductase which catalyzes the oxidation of menaquinol [5].
• Proteoliposomes containing menaquinone and fumarate reductase with or without hydrogenase catalyzed fumarate reduction by DMNH2 which did not generate a Delta(psi) [6].
• Proteoliposomes containing polysulfide reductase (Psr) and either hydrogenase or formate dehydrogenase isolated from the membrane fraction of Wolinella succinogenes catalyzed polysulfide respiration, provided that methyl-menaquinone-6 isolated from W. succinogenes was also present [7].

Chemical compound and disease context of HYPD

• Hydrogenase and fumarate reductase isolated from Wolinella succinogenes were incorporated into liposomes containing menaquinone [6].
• Two membrane anchors of Wolinella succinogenes hydrogenase and their function in fumarate and polysulfide respiration [8].
• The quinone-reactive Ni/Fe-hydrogenase of Wolinella succinogenes [9].

Biological context of HYPD

• The hydE gene is located on the genome downstream of the structural genes encoding the membrane-bound NiFe-hydrogenase complex (HydABC) and a putative protease (HydD) possibly involved in hydrogenase maturation [10].
• The photosynthetic bacterium Rhodobacter capsulatus synthesises a membrane-bound [NiFe] hydrogenase encoded by the H2 uptake hydrogenase (hup)SLC structural operon [4].

Anatomical context of HYPD

• The hydrogenase (Hyd) isolated from the cytoplasmic membrane of Wolinella succinogenes consists of three polypeptides (HydA, HydB and HydC) and contains cytochrome b (6.4 mumol/g protein), which was reduced upon the addition of H2 [9].

Associations of HYPD with chemical compounds

• We conclude that the same hydrogenase serves in the anaerobic respiration with fumarate and with polysulfide [8].
• We report the effect of diphenylene iodonium (Ph2I), a known inhibitor of mitochondrial complex I and of various monooxygenases on R. capsulatus hydrogenase activity [4].

Other interactions of HYPD

• The flavodoxin did not accept electrons from hydrogenase or formate dehydrogenase, the donor enzymes of electron transport to fumarate or polysulfide [11].

Analytical, diagnostic and therapeutic context of HYPD

• This is concluded from the haem B content of the isolated hydrogenase and is confirmed by the response of its cytochrome b to redox titration [1].

References