Exciton Delocalization Promotes Far-Red Absorption in a Tetrameric Chlorophyll <i>a</i> Light-Harvesting Complex from <i>Trachydiscus minutus</i>.

ABSTRACT: Photosynthetic organisms employ light-harvesting complexes (LHCs) to optimize energy capture under variable light conditions. The freshwater eustigmatophyte Trachydiscus minutus accumulates a red-shifted violaxanthin-chlorophyll protein (rVCP) that contributes to far-red light harvesting using only chlorophyll (Chl) a molecules, without chemical modification or substitution of pigments. Based on high-resolution cryo-EM and multiscale quantum chemical calculations, we uncovered a heterodimer-based tetrameric architecture, representing a unique oligomerization mode among LHCs. Within each heterodimer, Chls a are distinctively arranged adjacent to the terminal emitter, forming an unprecedentedly extended chlorophyll cluster. Quantum chemical calculations reveal three stro

SUBMITTER: Seki S 

PROVIDER: S-EPMC12752460 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature