Required for both formation and activity of the chloroplast NAD(P)H dehydrogenase (NDH) complex of the photosynthetic electron transport chain (PubMed:22274627). Functions in assembly or stabilization of the NDH complex; probably involved, together with NdhO and NdhH, in the formation of an NDH subcomplex A assembly intermediate (NAI500) (PubMed:22274627). Biogenesis factor component of the plastidial NDH subcomplex A. Specifically defective in the accumulation of subcomplex A, a stroma-protruding arm of the chloroplast NADH dehydrogenase-like complex (NDH).