Abstract
We describe a molecular mechanism tuning the functional properties of chlorophyll a (Chl-a) molecules in photosynthetic antenna proteins. Light-harvesting complexes from photosystem II in higher plants – specifically LHCII purified with α- or β-dodecyl-maltoside, along with CP29 – were probed by low-temperature absorption and resonance Raman spectroscopies. We show that hydrogen bonding to the conjugated keto carbonyl group of protein-bound Chl-a tunes the energy of its Soret and Qy absorption transitions, inducing red-shifts that are proportional to the strength of the hydrogen bond involved. Chls-a with non-H-bonded keto C131 groups exhibit the blue-most absorption bands, while both transitions are progressively red-shifted with increasing hydrogen-bonding strength – by up 382 & 605 cm−1 in the Qy and Soret band, respectively. These hydrogen bonds thus tune the site energy of Chl-a in light-harvesting proteins, determining (at least in part) the cascade of energy transfer events in these complexes.
Original language | English |
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Article number | 148078 |
Pages (from-to) | 1-6 |
Number of pages | 6 |
Journal | Biochimica et Biophysica Acta - Bioenergetics |
Volume | 1861 |
Issue number | 4 |
Early online date | 30 Aug 2019 |
DOIs | |
Publication status | Published - 1 Apr 2020 |
Funding
This work was supported by the ERC funding agency (PHOTPROT project), the French Infrastructure for Integrated Structural Biology (FRISBI) ANR-10-INBS-05 (France) , the Dutch Organization for scientific research via TOP grant (No 84713002 (Netherlands), ) and the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 675006 (SE2B).
Funders | Funder number |
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Dutch Organization for Scientific Research | 84713002 |
European Union's Horizon 2020 research and innovation program | |
Horizon 2020 Framework Programme | |
H2020 Marie Skłodowska-Curie Actions | 675006 |
European Research Council | |
French Infrastructure for Integrated Structural Biology | ANR-10-INBS-05 |
Keywords
- Chl-a
- Energy regulation
- Hydrogen bonds
- Light-harvesting
- Oxygenic photosynthesis