Abstract
In higher plants, the chloroplast NDH complex interacts with PSI to form the unique NDH-PSI supercomplex. Although it is well known that NDH mediates PSI cyclic and chlororespiratory electron transport, the nature of its electron input module is a long-standing mystery. To reveal the structure of NDH, we separated the NDH-PSI supercomplex by using BN-PAGE and analyzed it by LC/MS/MS. In addition to the NDH and PSI subunits, many proteins with unknown function were identified. Lhca5 and Lhca6 are required for the NDH-PSI formation. We also identified many proteins which are essential for the accumulation of NDH. Furthermore, we discovered three assembly intermediates of one NDH subcomplex (Subcomplex A) present in the chloroplast stroma. These complexes were immunoaffinity purified and analyzed by LC/MS/MS. On the basis of the results from proteomic and genetic analyses, we propose a working model of the NDH subcomplex A assembly.
