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Red-shifted chlorophyll a absorption in Light-Harvesting Complexes - The case of Trachydiscus minutus

ABSTRACT: Photosynthetic organisms harvest light for energy. Some eukaryotic algae have specialized in harvesting far-red light by tuning chlorophyll a absorption through a mechanism still to be elucidated. Here, we combined optically detected magnetic resonance and pulsed electron paramagnetic resonance measurements on red-adapted light-harvesting complexes, rVCP, isolated from the freshwater eustigmatophyte alga Trachydiscus minutus to identify the location of the pigments responsible for this remarkable adaptation. The pigments have been found to belong to an excitonic cluster of chlorophylls a at the core of the complex, close to the central carotenoids in L1/L2 sites. A pair of structural features of the Chl a403/a603 binding site, namely the histidine-to-asparagine substitution in the magnesium-ligation residue and the small size of the amino acid at the i-4 position, resulting in a [A/G]xxxN motif, are proposed to be the origin of this trait. Phylogenetic analysis of various eukaryotic red antennae identified several potential LHCs that could share this tuning mechanism.

INSTRUMENT(S): timsTOF Pro

ORGANISM(S): Trachydiscus Minutus

SUBMITTER: Alessandro Agostini Radek Litvin

PROVIDER: MSV000096023 | MassIVE | Fri Oct 04 07:17:00 BST 2024

SECONDARY ACCESSION(S): PXD056502

REPOSITORIES: MassIVE

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