Design principles of natural light harvesting as revealed by single molecule spectroscopy

TL;DR

This paper reviews recent insights from single molecule spectroscopy on how natural light-harvesting complexes in plants are optimized through specific design principles to efficiently capture and transfer solar energy while avoiding damage.

Contribution

It identifies and explains three key design principles of plant light-harvesting complexes revealed by single molecule spectroscopy studies.

Findings

Control of protein disorder for thermal energy dissipation

Design of protein environment for chromophore absorption

Efficient energy funneling to the emitter cluster

Abstract

Biology offers a boundless source of adaptation, innovation, and inspiration. A wide range of photosynthetic organisms exist that are capable of harvesting solar light in an exceptionally efficient way, using abundant and low-cost materials. These natural light-harvesting complexes consist of proteins that strongly bind a high density of chromophores to capture solar photons and rapidly transfer the excitation energy to the photochemical reaction centre. The amount of harvested light is also delicately tuned to the level of solar radiation to maintain a constant energy throughput at the reaction centre and avoid the accumulation of the products of charge separation. In this Review, recent developments in the understanding of light harvesting by plants will be discussed, based on results obtained from single molecule spectroscopy studies. Three design principles of the main light-harvesting antenna of plants will be highlighted: (a) fine, photoactive control over the intrinsic protein disorder to efficiently use intrinsically available thermal energy dissipation mechanisms; (b) the design of the protein microenvironment of a low-energy chromophore dimer to control the amount of shade absorption; (c) the design of the exciton manifold to ensure efficient funneling of the harvested light to the terminal emitter cluster.