Understanding the Energy Transfer Function of LHCII, the Major Light-Harvesting Complex of Green Plants

TLDR

LHCII is a chlorophyll‑rich trimeric membrane protein whose crystal structure was solved in 1994, containing 36–42 chlorophylls and 10–12 xanthophylls, and whose pigment–protein interactions have been extensively investigated. This review surveys key experimental findings from the past decade and links them to structural insights, highlighting pigment identities, spectroscopic traits, and pigment interactions that govern energy transfer dynamics. The authors analyze how pigment identities, their spectroscopic characteristics, and pigment–pigment interactions dictate both steady‑state polarized properties and singlet/triplet energy transfer pathways.

Abstract

Since the crystal structure of the major light-harvesting complex II (LHCII) of green plants was obtained by Kühlbrandt, Wang and Fujiyoshi (Nature 1994, 367, 614−621), this chlorophyll-containing trimeric membrane protein has been the subject of intensive investigation. The complex contains between 36 and 42 chlorophyll molecules per trimer (Chl a and Chl b) and 10 to 12 xanthophyll molecules (lutein, neoxanthin and violaxanthin). The protein displays a rich spectrum of interactions, both between pigments and between the pigments and the protein, and these interactions have been studied with a multitude of different techniques. In this article we present an overview of the most important experimental results that have become available over the past decade and relate these to the structural knowledge. Emphasis will be put on the pigment identities, their spectroscopic features, and the interactions between the pigments, which determine both steady-state (polarized) properties and singlet and triplet energy transfer dynamics. Remaining questions will be pinpointed and hopefully they can help direct research in the near future.