Photosystem II and the evolution of the light-harvesting antennae in vascular plants: a new concept

摘要

Cryo-electron crystallography of grana membranes has led to a new concept of the positioning of photosystem II (PSII) relative to its peripheral light-harvesting complex (LHCII). In projection, structural data reveals small domains surrounding the central PSII core which are compatible with the size and expected stoichiometry of the LHCII proteins. When viewed in 3D, however, these small domains are shown to occupy a membrane separate from the membrane plane that houses the PSII core region. This observation fits with the known morphology of the grana membrane preparation that consists of paired, tightly appressed membranes. The structural data has been confirmed by separate biochemical experiments where LHCII-enriched and core PSII-enriched membrane fractions havebeen isolated.