Sustained photoprotection involves enhanced fluorescence intermittency in a subpopulation of LHCII

Crepin, A.; Hoffmann, M. P.; Ilioaia, C.; Cunill-Semanat, E.; pascal, a.; Robert, B.; Romero, E.; Schlau-Cohen, G. S.; Malnoë, A.

doi:10.64898/2026.08.24.746725

bioRxiv · 10.64898/2026.08.24.746725

Sustained photoprotection involves enhanced fluorescence intermittency in a subpopulation of LHCII

Crepin, A.·Hoffmann, M. P.·Ilioaia, C.·Cunill-Semanat, E.·pascal, a.·Robert, B.·Romero, E.·Schlau-Cohen, G. S.·Malnoë, A.

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Abstract

Photoprotection against excess energy is essential for the survival of photosynthetic organisms under adverse conditions. In plants, excess energy can be dissipated as heat through non-photochemical quenching (NPQ) of chlorophyll fluorescence, involving the trimeric light-harvesting complex II (LHCII), the major antenna of photosystem II. How NPQ affects antenna proteins remains debated, especially as most studies focus on short-lived components artificially induced in vitro. Here, we characterize the effects of qH, a long-lived NPQ component, on the fluorescence properties of natively quenched LHCII. Single-molecule fluorescence measurements, combined with biochemical and biophysical ensemble approaches, reveal a larger and more quenched subpopulation of LHCII trimers exhibiting fluorescence intermittency in samples with qH compared to those without. This behavior is linked to a small conformational change that stabilizes a quenched state, enhancing photoprotection at the antenna level. These findings provide new insights into sustained NPQ and its role in regulating energy dissipation under natural light conditions.

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Crepin, A., Hoffmann, M. P., Ilioaia, C., Cunill-Semanat, E., pascal, a., Robert, B., Romero, E., Schlau-Cohen, G. S., Malnoë, A.. 2026-08-25. Sustained photoprotection involves enhanced fluorescence intermittency in a subpopulation of LHCII. https://doi.org/10.64898/2026.08.24.746725

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