Reversible inactivation of nitrogenase in Rhodobacter capsulatus strain W107I deleted in the draTG gene region

Upon addition of ammonium or removal of light, nitrogenase was reversibly i nactivated in a draTG gene deletion mutant of Rhodobacter capsulatus. Rever sible inactivation by exposure of the mutant to darkness followed the same kinetics as in control strains containing the draTG gene region. Reactivati on of nitrogenase by light was significantly Faster than removal of ADP-rib ose from component 2 of nitrogenase. The results show that, in R. capsulatu s, reversible inactivation of nitrogenase is independent of reversible ADP- ribosylation by the DRAT/DRAG enzyme system encoded by the draTG gene regio n. (C) 1999 Published by Elsevier Science B.V. All rights reserved.