State transitions in Chlamydomonas reinhardtii strongly modulate the functional size of photosystem II but not of photosystem I

C. Ünlü, B. Drop, R. Croce, H. van Amerongen

Research output: Contribution to journalArticleAcademicpeer-review

122 Citations (Scopus)

Abstract

Plants and green algae optimize photosynthesis in changing light conditions by balancing the amount of light absorbed by photosystems I and II. These photosystems work in series to extract electrons from water and reduce NADP+ to NADPH. Light-harvesting complexes (LHCs) are held responsible for maintaining the balance by moving from one photosystem to the other in a process called state transitions. In the green alga Chlamydomonas reinhardtii, a photosynthetic model organism, state transitions are thought to involve 80% of the LHCs. Here, we demonstrate with picosecond-fluorescence spectroscopy on C. reinhardtii cells that, although LHCs indeed detach from photosystem II in state 2 conditions, only a fraction attaches to photosystem I. The detached antenna complexes become protected against photodamage via shortening of the excited-state lifetime. It is discussed how the transition from state 1 to state 2 can protect C. reinhardtii in high-light conditions and how this differs from the situation in plants.
Original languageEnglish
Pages (from-to)3460-3465
JournalProceedings of the National Academy of Sciences of the United States of America
Volume111
Issue number9
DOIs
Publication statusPublished - 2014

Keywords

  • light-harvesting-complex
  • excitation-energy transfer
  • resolved chlorophyll fluorescence
  • alga scenedesmus-obliquus
  • protein-phosphorylation
  • thylakoid membrane
  • charge separation
  • supramolecular organization
  • arabidopsis-thaliana
  • angstrom resolution

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