Evidence for an Association of Ndh B, Ndh J Gene Products and Ferredoxin-NADP-reductase As Components of a Chloroplastic NAD(P)H Dehydrogenase Complex

Using non-denaturing gel electrophoresis and staining with nitro-blue tetrazolium, we reveal the presence of two NAD(P)H oxidoreductase activity bands within thylakoids membranes of Solanum tuberosum L. Second dimension SDS-PAGE and Western analysis show that one of the activity bands contains several polypeptides, two of them being recognized by antibodies directed against peptides corresponding to conserved domains of chloroplastic genes products NDH B and NDH J (at 32 and 18 kDa, respectively). Both activity bands also contain a polypeptide (around 36 kDa) recognized by an antibody directed against ferredoxin-NADP(+)-reductase (FNR). We conclude from these results that both chloroplastic ndh B and ndh J gene products are components of a thylakoid NAD(P)H dehydrogenase complex. The association with FNR is suggested to allow the complex to use NADPH instead of NADH as a preferential substrate.