Molecular dissection of photosystem I in higher plants: topology, structure and function

Photosystem I catalyses the light driven electron transfer from plastocyanin/cytochrome c(6) on the lumenal side of the thylakoid membrane to ferredoxin/flavodoxin at the stromal side. Photosystem I of higher plants consists of 18 different protein subunits. Fourteen of these make up the chlorophyll a-containing core, which also contains the cofactors involved in the electron transfer reactions, and four make up the peripheral chlorophyll a/b-containing antenna. Arabidopsis plants devoid of the nuclear-encoded photosystem I subunits have been obtained either by different suppression techniques or by insertional knock-out of the genes. This has allowed a detailed analysis of the role and function of the individual subunits. This review is focused on recent developments in the role of the individual subunit in the structure and function of photosystem I of higher plants.