Membrane curvature stress controls the maximal conversion of violaxanthin to zeaxanthin in the violaxanthin cycle—influence of α-tocopherol, cetylethers, linolenic acid, and temperature
| Autor: | Hans-Erik Åkerlund, Anna Szilágyi, Marianne Sommarin |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Inverted hexagonal phase (HII)
Zeaxanthin Membrane Fluidity Metabolic Clearance Rate Linolenic acid alpha-Tocopherol Biophysics Xanthophylls Xanthophyll cycle Photochemistry Mechanotransduction Cellular Thylakoids Biochemistry Thylakoid membrane chemistry.chemical_compound Membrane curvature stress Zeaxanthins Violaxanthin de-epoxidase (VDE) Lipid bilayer chemistry.chemical_classification biology Chemistry Temperature alpha-Linolenic Acid food and beverages Cell Biology biology.organism_classification Lipids Kinetics Membrane curvature Thylakoid Xanthophyll Spinach Stress Mechanical Ethers Signal Transduction Violaxanthin |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. 1768:2310-2318 |
| ISSN: | 0005-2736 |
| Popis: | Zeaxanthin, an important component in protection against overexcitation in higher plants, is formed from violaxanthin by the enzyme violaxanthin de-epoxidase. We have investigated factors that may control the maximal degree of conversion in the violaxanthin cycle. The conversion of violaxanthin to zeaxanthin in isolated spinach thylakoids was followed at different temperatures and in the presence of lipid packing modifiers. The maximum degree of conversion was found to be 35%, 70% and 80% at 4 degrees C, 25 degrees C and 37 degrees C respectively. In the presence of membrane modifying agents, known to promote non-lamellar structures (H(II)), such as linolenic acid the conversion increased, and the maximal level of violaxanthin de-epoxidation obtained was close to 100%. In contrast, substances promoting lamellar phases (L(alpha)), such as alpha-tocopherol and 8-cetylether (C(16)EO(8)), only 55% and 35% of the violaxanthin was converted at 25 degrees C, respectively. The results are interpreted in light of the lipid composition of the thylakoid membrane, and we propose a model where a negative curvature elastic stress in the thylakoid lipid bilayer is required for violaxanthin de-epoxidase activity. In this model zeaxanthin with its longer hydrophobic stretch is proposed to promote lamellar arrangements of the membrane. As a result, zeaxanthin relieves the curvature elastic stress, which in turn leads to inactivation of violaxanthin de-epoxidase. |
| Databáze: | OpenAIRE |
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