From red to blue to far-red in Lhca4: how does the protein modulate the spectral properties of the pigments?
| Autor: | Emilie Wientjes, Gemma Roest, Roberta Croce |
|---|---|
| Přispěvatelé: | Biophysics Photosynthesis/Energy, LaserLaB - Energy, Electron Microscopy |
| Rok vydání: | 2012 |
| Předmět: |
DYNAMICS
LHCII Models Molecular Time Factors Light GREEN PLANTS Biophysics Arabidopsis Photochemistry Biochemistry Absorption Light-harvesting complex chemistry.chemical_compound ANTENNA COMPLEXES Charge-transfer state TIME-RESOLVED FLUORESCENCE CRYSTAL-STRUCTURE Emission spectrum Photosynthesis Absorption (electromagnetic radiation) Photosystem lhca4 Quenching (fluorescence) Photosystem I Protein Complex Chemistry Arabidopsis Proteins PLANT PHOTOSYSTEM-I Non-photochemical quenching Circular Dichroism Far-red Cell Biology Pigments Biological Ihca4 CHLOROPHYLL Kinetics Spectrometry Fluorescence Tuning of spectroscopic properties A/B-BINDING-PROTEIN Mutagenesis Light harvesting-complex Chlorophyll Mutation Quantum Theory sense organs Chlorophyll Binding Proteins |
| Zdroj: | Wientjes, I E, Roest, G J & Croce, R 2012, ' From blue to red to far-red in Lhca4: how does the protein modulate the spectral properties of the pigments? ', Biochimica et Biophysica Acta (BBA)-Bioenergetics, vol. 1817, pp. 711-717 . https://doi.org/10.1016/j.bbabio.2012.02.030 Biochimica et Biophysica Acta (BBA)-Bioenergetics, 1817, 711-717. Elsevier Biochimica et Biophysica Acta, 1817(5), 711-717 |
| ISSN: | 0006-3002 0005-2728 |
| DOI: | 10.1016/j.bbabio.2012.02.030 |
| Popis: | The first event of photosynthesis is the harvesting of solar energy by a large array of pigments. These pigments are coordinated to proteins that organize them to assure efficient excitation energy transfer. The protein plays an essential role in tuning the spectroscopic properties of the pigments, by determining their site energy and/or by favoring pigment-pigments interactions. Here we investigate how the protein modulates the pigment properties by using a single-point-mutation approach. We monitor changes in the low-energy absorption/emission band of Lhca4, which is well separated from the bulk absorption and thus represents an attractive model system. Moreover, it was recently shown that Lhca4 exists in at least two conformations, a dominating one emitting at 720 nm and a second one emitting at 685 nm (Kruger et al. PNAS 2011). Here we show that a single amino-acid substitution (from Asn to Gln, which are both chlorophyll-binding residues and only differ for one C-C bond), moves the equilibrium almost completely towards the 685-nm conformation. This indicates that small changes in the protein can have a large effect on the properties of the pigments. We show that His99, which was suggested to coordinate a red-absorbing chlorophyll (Melkozernov and Blankenship, JBC 2003), is not a chlorophyll ligand. We also show that single amino-acid substitutions nearby the chlorophylls allow to tune the emission spectrum of the pigments over a wide range of wavelengths and to modulate the excited-state lifetimes of the complex. These findings are discussed in the light of previously proposed non-photochemical quenching models. ispartof: Biochimica et Biophysica Acta. Bioenergetics vol:1817 issue:1817 pages:711-717 ispartof: location:Netherlands status: published |
| Databáze: | OpenAIRE |
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