Characterization of the interaction of dinitrogenase reductase-activating glycohydrolase from Rhodospirillum rubrum with bacterial membranes.

The interaction of dinitrogenase reductase-activating glycohydrolase (DRAG) with bacterial membranes and the solubilization of DRAG in response to nucleotides were characterized. Purified DRAG from Rhodospirillum rubrum reversibly bound bacterial pellet fractions from Rsp. rubrum and other nitrogen-fixing bacteria. DRAG saturated the membrane fraction of Rsp. rubrum at a concentration of 0.2 mol DRAG/mol bacteriochlorophyll, suggesting that the DRAG-binding species is prevalent in the membrane. DRAG bound poorly to phospholipid vesicles, suggesting a protein requirement for DRAG interaction with the membrane. Guanosine and uridine tri- and di-nucleotides specifically dissociated DRAG from the pellet fractions of Rsp. rubrum and Azotobacter vinelandii, while adenosine nucleotides had no dissociative effect. Guanosine 5'-triphosphate dissociated DRAG from the membrane at a concentration causing 50% dissociation (EC50) of 5.0 +/- 0.5 mM; guanosine disphosphate had an EC50 of 15.0 +/- 2.0 mM. We propose that GTP is a potential participant in the regulation of DRAG, possibly controlling the extent of DRAG association with the membrane. Keywords Rhodospirillum rubrum. Membrane. association. Nitrogenase regulation. Nucleotide bindinghttp://link.springer-ny. com/link/service/journals/00203/bibs/172n1p51.html