Journal of Molecular Biology vol:234 issue:2 pages:508-512
The nucleotide sequence of a 2.2 kb region downstream of the hydrogenase structural genes in Bradyrhizobium japonicum was determined. Four genes encoding predicted polypeptides of 27.8 (HupC), 21.4 (HupD), 10.6 (HupF) and 15.8 (HupG) kDa were identified, of which the first three probably belong to the same operon as the hup structural genes, hupS and hupL. 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. Also HupD, HupF and HupG are homologous to genes involved in processing, maturation, functioning and regulation of hydrogenase activity in various hydrogen-oxidizing bacteria.