Structure and Function of the Antenna System in Photosystem I

Abstract

Photosystem I (PS I) is a large, membrane protein complex, consisting of 12--15 proteins and more than 100 bound cofactors, that catalyzes light-driven electron transfer across the photosynthetic membrane in cyanobacteria, green algae and plants. Photosystem I is unique compared to other photosynthetic systems because the majority of the antenna pigments and the cofactors of the electron transport system are bound to the same protein subunits. Photosystem I can therefore be regarded as a joint reaction center-core antenna system. In this chapter, PS I is described with respect to both structure and function. The kinetics of energy transfer and trapping are discussed in the light of the structural information. We also discuss models for the interaction of PS I with the external antenna complexes in cyanobacteria and plants.