LHCSR1 induces a fast and reversible pH-dependent fluorescence quenching in LHCII in Chlamydomonas reinhardtii cells

Emine Dinc, Lijin Tian, Laura M. Roy, Robyn Roth, Ursula Goodenough, Roberta Croce

Research output: Contribution to journalArticlepeer-review

70 Scopus citations

Abstract

To avoid photodamage, photosynthetic organisms are able to thermally dissipate the energy absorbed in excess in a process known as nonphotochemical quenching (NPQ). Although NPQ has been studied extensively, the major players and the mechanism of quenching remain debated. This is a result of the difficulty in extracting molecular information from in vivo experiments and the absence of a validation system for in vitro experiments. Here, we have created a minimal cell of the green alga Chlamydomonas reinhardtii that is able to undergo NPQ. We show that LHCII, the main light harvesting complex of algae, cannot switch to a quenched conformation in response to pH changes by itself. Instead, a small amount of the protein LHCSR1 (light-harvesting complex stress related 1) is able to induce a large, fast, and reversible pH-dependent quenching in an LHCII-containing membrane. These results strongly suggest that LHCSR1 acts as pH sensor and that it modulates the excited state lifetimes of a large array of LHCII, also explaining the NPQ observed in the LHCSR3-less mutant. The possible quenching mechanisms are discussed.

Original languageEnglish
Pages (from-to)7673-7678
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number27
DOIs
StatePublished - 5 Jul 2016
Externally publishedYes

Keywords

  • Green algae
  • Ight-harvesting
  • Nphotochemical quenching
  • Photosynthesis
  • Ylakoid membranes

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