LOCALIZATION OF HYDROGENASE IN THE PURPLE SULFUR BACTERIUM THIOCAPSA-ROSEOPERSICINA

The localization of hydrogenase in the phototrophic bacterium Thiocaps a roseopersicina was investigated by subcellular fractionations, and t ransmission electron microscopic immunocytochemistry. By using sonicat ed cells and measuring in vitro hydrogenase activities in soluble and membrane fractions, respectively, a weak hydrophobic interaction betwe en the hydrogenase enzyme and the T. roseopersicina membranes was obse rved. Polyclonal antisera directed against the purified hydrogenase we re raised in rabbits and exhibited one band in native-PAGE/Western imm unoblot analysis. Native-PAGE/activity stain confirmed the identity of this band as being hydrogenase. Immunocytolocalization experiments us ing ultrathin sections showed an internal localization of the hydrogen ase enzyme. A higher specific labeling was associated with chromatopho res, indicating a possible coupling of hydrogenase with the photosynth etic membranes in the T roseopersicina cells.