Abstract
PsbQ, an extrinsic subunit of photosystem II, is a nuclear-encoded protein that optimaizes the water-splitting reaction. In addition to PsbQ, Arabidopsis has three PsbQ paralogs, the PsbQ-Like (PQL) proteins. Phylogenetic analysis suggested that PQL proteins specifically present in higher plants.
To estimate the function of PQL proteins, we investigated the expression profiles of Arabidpsis PQL genes using the microarray data from AtGenExpress using ATTED-II program.
Our in silico analysis showed that PQL genes were coexpressed with genes encoding subunits of the chloroplast NAD(P)H dehydrogenase(NDH) complex; NdhL, NdhN, NdhO, Ndf4, and PPL2. Consistent with co-expression profiles, the activity and protein level of the NDH complex in thylakoids were severely decreased in each of pql mutants. These results suggest that PQL proteins would be novel thylakoid lumenal proteins required for accumulation of the NDH complex in Arabidopsis.
