Arachidonic acid is important for efficient use of light by the microalga Lobosphaera incisa under chilling stress

Zorin, B.; Pal-Nath, D.; Lukyanov, A.; Smolskaya, S.; Kolusheva, S.; Didi-Cohen, S.; Boussiba, S.; Cohen, Z.; Khozin-Goldberg, I.; Solovchenko, A.

Авторы: Zorin B., Pal-Nath D., Lukyanov A., Smolskaya S., Kolusheva S., Didi-Cohen S., Boussiba S., Cohen Z., Khozin-Goldberg I., Solovchenko A.
Журнал: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Год издания: 2017
Издательство: Elsevier BV
Местоположение издательства: Netherlands
DOI: 10.1016/j.bbalip.2017.04.008
Аннотация: The oleaginous microalga Lobosphaera incisa (Trebouxiophyceae, Chlorophyta) contains arachidonic acid (ARA, 20:4 n-6) in all membrane glycerolipids and in the storage lipid triacylglycerol. The optimal growth temperature of the wild-type (WT) strain is 25 °C; chilling temperatures (≤ 15 °C) slow its growth. This effect is more pronounced in the delta-5-desaturase ARA-deficient mutant P127, in which ARA is replaced with dihomo-γ-linolenic acid (DGLA, 20:3 n-6). In nutrient-replete cells grown at 25 °C, the major chloroplast lipid monogalactosylglycerol (MGDG) were dominated by C18/C16 species in both strains. Yet ARA constituted over 10% of the total fatty acids in the WT MGDG as a component of C20/C18 and C20/C20 species, whereas DGLA was only a minor component of MGDG in P127. Both strains increased the percentage of 18:3 n-3 in membrane lipids under chilling temperatures. The temperature downshift led to a dramatic increase in triacylglycerol at the expense of chloroplast lipids. WT and P127 showed a similarly high photochemical quantum yield of photosystem II, whereas non-photochemical quenching (NPQ) and violaxanthin de-epoxidation were drastically higher in P127, especially at 15 °C. Fluorescence anisotropy measurements indicated that ARA-containing MGDG might contribute to sustaining chloroplast membrane fluidity upon dropping to the chilling temperature. We hypothesize that conformational changes in chloroplast membranes and increased rigidity of the ARA-deficient MGDG of P127 at chilling temperatures is not compensated by trienoic fatty acids. This might ‘lock’ violaxanthin de-epoxidase in the activated state causing high constitutive NPQ and alleviate the risk of photodamage under chilling conditions in the mutant.
Добавил в систему: Соловченко Алексей Евгеньевич

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Arachidonic acid is important for efficient use of light by the microalga Lobosphaera incisa under chilling stressстатья

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