Lhcx proteins provide photoprotection via thermal dissipation of absorbed light in the diatom Phaeodactylum tricornutum

• Published in: Nature communications Vol. 10; no. 1; pp. 4167 - 12
• Main Authors: Buck, Jochen M, Sherman, Jonathan, Bártulos, Carolina Río, Serif, Manuel, Halder, Marc, Henkel, Jan, Falciatore, Angela, Lavaud, Johann, Gorbunov, Maxim Y, Kroth, Peter G, Falkowski, Paul G, Lepetit, Bernard
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 13.09.2019; Nature Publishing Group UK; Nature Portfolio
• Subjects: Absorption; Absorption cross sections; Diatoms - metabolism; Diatoms - physiology; Energy dissipation; Environmental conditions; Life Sciences; Light; Microbiology and Parasitology; Mutants; Phaeodactylum tricornutum; Photosynthesis - physiology; Photosystem II; Photosystem II Protein Complex - metabolism; Photosystem II Protein Complex - physiology; Plankton; Proteins; Thermal energy; Xanthophylls; Xanthophylls - metabolism; Molecular biology; Non-photochemical quenching; Physiology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-12043-6

Diatoms possess an impressive capacity for rapidly inducible thermal dissipation of excess absorbed energy (qE), provided by the xanthophyll diatoxanthin and Lhcx proteins. By knocking out the Lhcx1 and Lhcx2 genes individually in Phaeodactylum tricornutum strain 4 and complementing the knockout lines with different Lhcx proteins, multiple mutants with varying qE capacities are obtained, ranging from zero to high values. We demonstrate that qE is entirely dependent on the concerted action of diatoxanthin and Lhcx proteins, with Lhcx1, Lhcx2 and Lhcx3 having similar functions. Moreover, we establish a clear link between Lhcx1/2/3 mediated inducible thermal energy dissipation and a reduction in the functional absorption cross-section of photosystem II. This regulation of the functional absorption cross-section can be tuned by altered Lhcx protein expression in response to environmental conditions. Our results provide a holistic understanding of the rapidly inducible thermal energy dissipation process and its mechanistic implications in diatoms.