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Constrained geometric dynamics of the Fenna–Matthews–Olson complex: the role of correlated motion in reducing uncertainty in excitation energy transfer

Lookup NU author(s): Dr Daniel ColeORCiD


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The trimeric Fenna–Mathews–Olson (FMO) complex of green sulphur bacteria is a well-studied example of a photosynthetic pigment–protein complex, in which the electronic properties of the pigments are modified by the protein environment to promote efficient excitonic energy transfer from antenna complexes to the reaction centres. By a range of simulation methods, many of the electronic properties of the FMO complex can be extracted from knowledge of the static crystal structure. However, the recent observation and analysis of long-lasting quantum dynamics in the FMO complex point to protein dynamics as a key factor in protecting and generating quantum coherence under laboratory conditions. While fast inter- and intra-molecular vibrations have been investigated extensively, the slow, conformational dynamics which effectively determine the optical inhomogeneous broadening of experimental ensembles has received less attention. The following study employs constrained geometric dynamics to study the flexibility in the protein network by efficiently generating the accessible conformational states from the published crystal structure. Statistical and principle component analyses reveal highly correlated low frequency motions between functionally relevant elements, including strong correlations between pigments that are excitonically coupled. Our analysis reveals a hierarchy of structural interactions which enforce these correlated motions, from the level of monomer-monomer interfaces right down to the α-helices, β-sheets and pigments. In addition to inducing strong spatial correlations across the conformational ensemble, we find that the overall rigidity of the FMO complex is exceptionally high. We suggest that these observations support the idea of highly correlated inhomogeneous disorder of the electronic excited states, which is further supported by the remarkably low variance (typically <5 %) of the excitonic couplings of the conformational ensemble.

Publication metadata

Author(s): Fokas AS, Cole DJ, Chin AW

Publication type: Article

Publication status: Published

Journal: Photosynthesis Research

Year: 2014

Volume: 122

Issue: 3

Pages: 275-292

Print publication date: 01/12/2014

Online publication date: 18/07/2014

Acceptance date: 18/07/2014

ISSN (print): 01668595

ISSN (electronic): 15735079

Publisher: Springer Netherlands


DOI: 10.1007/s11120-014-0027-3


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