Chapter

Photoprotection, Photoinhibition, Gene Regulation, and Environment

Volume 21 of the series Advances in Photosynthesis and Respiration pp 145-153

A Protein Family Saga: From Photoprotection to Light-Harvesting (and Back?)

  • Stefan JanssonAffiliated withUmeå Plant Science Centre Department of Plant Physiology, Umeå University

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Summary

Photoprotection seems to be an intrinsic property of light-harvesting systems, and an interesting question to address is whether the light-harvesting or the photoprotection function was the “original” function, and which function evolved subsequently. It appears that the cyanobacterial one-helix proteins, the presumed ancestors to the LHC proteins, were not designed as antenna proteins but were involved in photoprotection and /or pigment metabolism. Some intermediate steps (two- and four-helix proteins) also seem to have photoprotective functions. The antenna function appeared later in evolution, and many different LHC proteins with somewhat diversified functions arose. To some extent, this happened before the lineages leading to Chlamydomonas and higher plants separated, but further diversification also took place following the split, and some of the proteins may have evolved in a direction away from optimizing light harvesting. When the evolution of feedback de-excitation is put into this evolutionary scheme, it is likely that xanthophyll conversions, that evolved previously to optimize photoprotection, were starting to be used as indicators of light stress and regulators of antenna function.