Abstract
The light-independent protochlorophyllide (Pchlide) reductase (DPOR) is the determinant enzyme for the greening in darkness. In the previous study, we have reported the reconstitution of DPOR activity with the purified components, BchL and BchNB. In this report, we have constructed an over-expression system of each component of DPOR with a broad host range vector pJRD215 in Rhodobacter capsulatus to purify the components in an amount enough for further characterization. A pair of plasmids, pYCL10 and pYCNB111, was constructed on pJRD215 to over-express BchL and BchNB, respectively, under the control of the puc promoter. This expression system allowed purifying 100-300 μg of each component from a 500-ml culture. Interestingly, the purified BchNB component showed bright green color, with the absorption spectrum indicating the binding of Pchlide. This feature suggests that the BchNB component provides a binding site and a catalytic center in the DPOR complex.
