Phasor Analysis Reveals Multicomponent Fluorescence Kinetics in the LH2 Complex from Marichromatium purpuratum

0565868 - MBÚ 2023 RIV US eng J - Článek v odborném periodiku
Elvers, I. - Nguyen-Phan, T. C. - Gardiner, Alastair T. - Hunter, C. N. - Cogdell, R. J. - Köhler, J.
Phasor Analysis Reveals Multicomponent Fluorescence Kinetics in the LH2 Complex from Marichromatium purpuratum.
Journal of Physical Chemistry B. Roč. 126, č. 49 (2022), s. 10335-10346. ISSN 1520-6106. E-ISSN 1520-5207
Institucionální podpora: RVO:61388971
Klíčová slova: Phasor Analysis * Fluorescence * LH2 Complex * Marichromatium purpuratum
Obor OECD: Microbiology
Impakt faktor: 3.3, rok: 2022
Způsob publikování: Omezený přístup
https://pubs.acs.org/doi/10.1021/acs.jpcb.2c04983

We investigated the fluorescence kinetics of LH2 complexes from Marichromatium purpuratum, the cryo-EM structure of which has been recently elucidated with 2.4 Å resolution. The experiments have been carried out as a function of the excitation density by varying both the excitation fluence and the repetition rate of the laser excitation. Instead of the usual multiexponential fitting procedure, we applied the less common phasor formalism for evaluating the transients because this allows for a model-free analysis of the data without a priori knowledge about the number of processes that contribute to a particular decay. For the various excitation conditions, this analysis reproduces consistently three lifetime components with decay times below 100 ps, 500 ps, and 730 ps, which were associated with the quenched state, singlet-triplet annihilation, and fluorescence decay, respectively. Moreover, it reveals that the number of decay components that contribute to the transients depends on whether the excitation wavelength is in resonance with the B800 BChl a molecules or with the carotenoids. Based on the mutual arrangement of the chromophores in their binding pockets, this leads us to conclude that the energy transfer pathways within the LH2 complex of this species differ significantly from each other for exciting either the B800 BChl molecules or the carotenoids. Finally, we speculate whether the illumination with strong laser light converts the LH2 complexes studied here into a quenched conformation that might be related to the development of the non-photochemical quenching mechanism that occurs in higher plants.
Trvalý link: https://hdl.handle.net/11104/0337359