Stability of water-soluble chlorophyll protein (WSCP) depends on phytyl conformation

Abstract

Water-soluble chlorophyll proteins (WSCP) from Brassicaceae form homotetrameric chlorophyll (Chl)–protein complexes binding one Chl per apoprotein and no carotenoids. Despite the lack of photoprotecting photoprotecting pigments, the complex-bound Chls displays a remarkable stability toward photodynamic photodynamic damage. On the basis of a mutational study, we show that not only the presence of the phytyls phytyls is necessary for photoprotection in WSCPs, as we previously demonstrated, but also is their correct correct conformation and localization. The extreme heat stability of WSCP also depends on the presence presence of the phytyl chains, confirming their relevance for the unusual stability of WSCP.