期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
卷 1837, 期 6, 页码 899-907出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbabio.2014.02.021
关键词
Photosynthesis; Non-photochemical quenching; Diatom; Light-harvesting complex; Xanthophyll cycle
资金
- HARVEST Marie Curie Research Training Network [PITN-GA-2009-238017]
- BioSolar Cells - Dutch Ministry of Economic Affairs
Diatoms, which are primary producers in the oceans, can rapidly switch on/off efficient photoprotection to respond to fast light-intensity changes in moving waters. The corresponding thermal dissipation of excess-absorbed-light energy can be observed as non-photochemical quenching (NPQ) of chlorophyll a fluorescence. Fluorescence-induction measurements on Cyclotella meneghiniana diatoms show two NPQ processes: qE(1) relaxes rapidly in the dark while qE(2) remains present upon switching to darkness and is related to the presence of the xanthophyll-cycle pigment diatoxanthin (Dtx). We performed picosecond fluorescence measurements on cells locked in different (quenching) states, revealing the following sequence of events during full development of NPQ At first, trimers of light-harvesting complexes (fucoxanthin-chlorophyll a/c proteins), or FCPa, become quenched, while being part of photosystem II (PSII), due to the induced pH gradient across the thylakoid membrane. This is followed by (partial) detachment of FCPa from PSII after which quenching persists. The pH gradient also causes the formation of Dtx which leads to further quenching of isolated PSII cores and some aggregated FCPa. In subsequent darkness, the pH gradient disappears but Dtx remains present and quenching partly pertains. Only in the presence of some light the system completely recovers to the unquenched state. (C) 2014 Elsevier B.V. All rights reserved.
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