期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 116, 期 17, 页码 8320-8325出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1817796116
关键词
photosynthesis; low pH; photosystem II; fluorescence; ultrafast spectroscopy
资金
- European Commission Marie Curie Actions Individual Fellowship [799083]
- European Research Council via an ERC consolidator grant [214113]
- Dutch Organization for Scientific Research (NWO) via a Vici grant
- Marie Curie Actions (MSCA) [799083] Funding Source: Marie Curie Actions (MSCA)
Sunlight drives photosynthesis but can also cause photodamage. To protect themselves, photosynthetic organisms dissipate the excess absorbed energy as heat, in a process known as nonphotochemical quenching (NPQ). In green algae, diatoms, and mosses, NPQ depends on the light-harvesting complex stress-related (LHCSR) proteins. Here we investigated NPQ in Chlamydomonas reinhardtii using an approach that maintains the cells in a stable quenched state. We show that in the presence of LHCSR3, all of the photosystem (PS) II complexes are quenched and the LHCs are the site of quenching, which occurs at a rate of similar to 150 ps(-1) and is not induced by LHCII aggregation. The effective light-harvesting capacity of PSII decreases upon NPQ, and the NPQ rate is independent of the redox state of the reaction center. Finally, we could measure the pH dependence of NPQ, showing that the luminal pH is always above 5.5 in vivo and highlighting the role of LHCSR3 as an ultrasensitive pH sensor.
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