Nucleotide sequences of membrane-bound hydrogenase gene in Alcaligenes hydrogenophilus

The nucleotide sequences of membrane-bound hydrogenase small (hupS) and large (hupL) subunit genes of hydrogen bacterium Alcaligenes hydrogenophilus were determined. The hupS and hupL genes encoded polypeptides of 363 and 619 amino acids, respectively. The hupS was located upstream of hupL with 35bp of intergenic region. The consensus ribosome-binding sequences were identified upstream of the start codons of hupS and hupL. Amino acid sequence of hupS is very similar to that of Rhodobacter capsulatus, Bradyrhizobium japonicum, and Azotobacter vinelandii at amino acid levels of 82%, 77%, and 81%, respectively. Similarly, amino acid sequence of HupL is similar to that of R. capsulatus, B. japonicum, and A. vinelandii at amino acid levels of 63%, 65%, and 68%, respectively. Northern hybridization analysis showed that hupS and hupL were co-transcribed, and addition of fructose to the culture medium remarkably decreased the amount of mRNA transcribed from hupS and hupL.