CLONING AND SEQUENCES OF THE STRUCTURAL (HUPSLC) AND ACCESSORY (HUPDHI) GENES FOR HYDROGENASE BIOSYNTHESIS IN THIOCAPSA-ROSEOPERSICINA

The first molecular biology study on the purple sulfur photosynthetic bacterium Thiocapsa roseopersicina is reported, namely, the constructi on of cosmid libraries and isolation of a hydrogenase gene cluster by hybridization with hydrogenase structural genes from the purple non-su lfur bacterium, Rhodobacter capsulatus. The sequenced gene cluster con tains six open reading frames, the products of which show significant degrees of identity (from 40 to 78%) with hydrogenase gene products ne cessary for biosynthesis of the group-I of [NiFe]hydrogenases. The str uctural hupSLC genes encode the small and large hydrogenase subunits a nd a hydrophobic protein shown to accept electrons from hydrogenase in R. capsulatus. They are followed downstream by three genes, hupDHI, w hich are similar to hydrogenase accessory genes found in other bacteri a.