Dataset Information

Carotenoid-Chlorophyll Interactions in a Photosynthetic Antenna Protein: A Supramolecular QM/MM Approach.

ABSTRACT: Multichromophoric interactions control the initial events of energy capture and transfer in the light harvesting peridinin-chlorophyll a protein (PCP) from marine algae dinoflagellates. Due to the van der Waals association of the carotenoid peridinin (Per) with chlorophyll a in a unique 4:1 stoichiometric ratio, supramolecular quantum mechanical/molecular mechanical (QM/MM) calculations are essential to accurately describe structure, spectroscopy, and electronic coupling. We show that, by enabling inter-chromophore electronic coupling, substantial effects arise in the nature of the transition dipole moment and the absorption spectrum. We further hypothesize that inter-protein domain Per-Per interactions are not negligible, and are needed to explain the experimental reconstruction features of the spectrum in wild-type PCP.

SUBMITTER: Guberman-Pfeffer MJ

PROVIDER: S-EPMC6222738 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Carotenoid-Chlorophyll Interactions in a Photosynthetic Antenna Protein: A Supramolecular QM/MM Approach.

Guberman-Pfeffer Matthew J MJ Gascón José A JA

Molecules (Basel, Switzerland) 20181010 10

Multichromophoric interactions control the initial events of energy capture and transfer in the light harvesting peridinin-chlorophyll <i>a</i> protein (PCP) from marine algae dinoflagellates. Due to the van der Waals association of the carotenoid peridinin (Per) with chlorophyll <i>a</i> in a unique 4:1 stoichiometric ratio, supramolecular quantum mechanical/molecular mechanical (QM/MM) calculations are essential to accurately describe structure, spectroscopy, and electronic coupling. We show t ...[more]

PMID: 30308965

Similar Datasets

Project description:Plants possess an essential ability to rapidly down-regulate light-harvesting in response to high light. This photoprotective process involves the formation of energy-quenching interactions between the chlorophyll and carotenoid pigments within the antenna of Photosystem II (PSII). The nature of these interactions is currently debated, with, among others, 'incoherent' or 'coherent' quenching models (or a combination of the two) suggested by a range of time-resolved spectroscopic measurements. In 'incoherent quenching', energy is transferred from a chlorophyll to a carotenoid and is dissipated due to the intrinsically short excitation lifetime of the latter. 'Coherent quenching' would arise from the quantum mechanical mixing of chlorophyll and carotenoid excited state properties, leading to a reduction in chlorophyll excitation lifetime. The key parameters are the energy gap, [Formula: see text] and the resonance coupling, J, between the two excited states. Coherent quenching will be the dominant process when [Formula: see text] i.e., when the two molecules are resonant, while the quenching will be largely incoherent when [Formula: see text] One would expect quenching to be energetically unfavorable for [Formula: see text] The actual dynamics of quenching lie somewhere between these limiting regimes and have non-trivial dependencies of both J and [Formula: see text] Using the Hierarchical Equation of Motion (HEOM) formalism we present a detailed theoretical examination of these excitation dynamics and their dependence on slow variations in J and [Formula: see text] We first consider an isolated chlorophyll-carotenoid dimer before embedding it within a PSII antenna sub-unit (LHCII). We show that neither energy transfer, nor the mixing of excited state lifetimes represent unique or necessary pathways for quenching and in fact discussing them as distinct quenching mechanisms is misleading. However, we do show that quenching cannot be switched 'on' and 'off' by fine tuning of [Formula: see text] around the resonance point, [Formula: see text] Due to the large reorganization energy of the carotenoid excited state, we find that the presence (or absence) of coherent interactions have almost no impact of the dynamics of quenching. Counter-intuitively significant quenching is present even when the carotenoid excited state lies above that of the chlorophyll. We also show that, above a rather small threshold value of [Formula: see text]quenching becomes less and less sensitive to J (since in the window [Formula: see text] the overall lifetime is independent of it). The requirement for quenching appear to be only that [Formula: see text] Although the coherent/incoherent character of the quenching can vary, the overall kinetics are likely robust with respect to fluctuations in J and [Formula: see text] This may be the basis for previous observations of NPQ with both coherent and incoherent features.

Dataset Information

Carotenoid-Chlorophyll Interactions in a Photosynthetic Antenna Protein: A Supramolecular QM/MM Approach.

Publications

Carotenoid-Chlorophyll Interactions in a Photosynthetic Antenna Protein: A Supramolecular QM/MM Approach.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets