Robust light harvesting by a noisy antenna

Malý, P., Gardiner, A. T., Cogdell, R. J. , van Grondelle, R. and Mančal, T. (2018) Robust light harvesting by a noisy antenna. Physical Chemistry Chemical Physics, 20(6), pp. 4360-4372. (doi: 10.1039/c7cp06139k) (PMID:29368769)

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Photosynthetic light harvesting can be very efficient in solar energy conversion while taking place in a highly disordered and noisy physiological environment. This efficiency is achieved by the ultrafast speed of the primary photosynthetic processes, which is enabled by a delicate interplay of quantum effects, thermodynamics and environmental noise. The primary processes take place in light-harvesting antennas built from pigments bound to a fluctuating protein scaffold. Here, we employ ultrafast single-molecule spectroscopy to follow fluctuations of the femtosecond energy transfer times in individual LH2 antenna complexes of purple bacteria. By combining single molecule results with ensemble spectroscopy through a unified theoretical description of both, we show how the protein fluctuations alter the excitation energy transfer dynamics. We find that from the thirteen orders of magnitude of possible timescales from picoseconds to minutes, the relevant fluctuations occur predominantly on a biological timescale of seconds, i.e. in the domain of slow protein motion. The measured spectra and dynamics can be explained by the protein modulating pigment excitation energies only. Moreover, we find that the small spread of pigment mean energies allows for excitation delocalization between the coupled pigments to survive. These unique features provide fast energy transport even in the presence of disorder. We conclude that this is the mechanism that enables LH2 to operate as a robust light-harvester, in spite of its intrinsically noisy biological environment.

Item Type:Articles
Additional Information:P. M. and T. M. gratefully acknowledge the support by grant no. 17-22160S from the Czech Science Foundation (GACR). P. M. and R. v. G. were supported by the European Research Council (ERC) through an Advanced Investigator Grant (no. 267333, PHOTPROT) to R. v. G. and by the Canadian Institute for Advanced Research (CIFAR). R. v. G. was further supported by the EU FP7 project PAPETS (GA 323901). R. J. C. and A. T. G., were supported by the Photosynthetic Antenna Research Centre (PARC), an Energy Frontier Research Centre funded by the DOE, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC 0001035.
Glasgow Author(s) Enlighten ID:Cogdell, Professor Richard and Gardiner, Dr Alastair
Authors: Malý, P., Gardiner, A. T., Cogdell, R. J., van Grondelle, R., and Mančal, T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Physical Chemistry Chemical Physics
Publisher:Royal Society of Chemistry (RSC)
ISSN (Online):1463-9084
Published Online:25 January 2018
Copyright Holders:Copyright © 2018 the Owner Societies
First Published:First published in Physical Chemistry Chemical Physics 20(6): 4360-4372
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
502612Photosynthetic Antenna Research Center (PARC)Richard CogdellUS Department of Energy (USDOE)DE-SC0001035RI MOLECULAR CELL & SYSTEMS BIOLOGY