title: Photosystem II Subunit PsbS Is Involved in the Induction of LHCSR Protein-dependent Energy Dissipation in Chlamydomonas reinhardtii.
abstract: Non-photochemical quenching of excess excitation energy is an important photoprotective mechanism in photosynthetic organisms. In Arabidopsis thaliana, a high quenching capacity is constitutively present and depends on the PsbS protein. In the green alga Chlamydomonas reinhardtii, non-photochemical quenching becomes activated upon high light acclimation and requires the accumulation of light harvesting complex stress-related (LHCSR) proteins. Expression of the PsbS protein in C. reinhardtii has not been reported yet. Here, we show that PsbS is a light-induced protein in C. reinhardtii, whose accumulation under high light is further controlled by CO2 availability. PsbS accumulated after several hours of high light illumination at low CO2 At high CO2, however, PsbS was only transiently expressed under high light and was degraded after 1 h of high light exposure. PsbS accumulation correlated with an enhanced non-photochemical quenching capacity in high light-acclimated cells grown at low CO2 However, PsbS could not compensate for the function of LHCSR in an LHCSR-deficient mutant. Knockdown of PsbS accumulation led to reduction of both non-photochemical quenching capacity and LHCSR3 accumulation. Our data suggest that PsbS is essential for the activation of non-photochemical quenching in C. reinhardtii, possibly by promoting conformational changes required for activation of LHCSR3-dependent quenching in the antenna of photosystem II.
authors.affiliation: From the Plant Biochemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Viviana
authors.initials: V
authors.lastname: Correa-Galvis
authors.affiliation: From the Plant Biochemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Redekop
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, and.
authors.forename: Katharine
authors.initials: K
authors.lastname: Guan
authors.affiliation: From the Plant Biochemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Griess
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, and.
authors.forename: Thuy B
authors.initials: TB
authors.lastname: Truong
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, and.
authors.forename: Setsuko
authors.initials: S
authors.lastname: Wakao
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, and Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Niyogi
authors.affiliation: From the Plant Biochemistry, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany, pjahns@hhu.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Jahns
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000235:genetics; D055785:Gene Knockdown Techniques; D008027:Light; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; D002245:Carbon Dioxide
keywords: Chlamydomonas; NPQ; Photoprotection; PsbS; light acclimation; light-harvesting complex (antenna complex); pH regulation; photosynthesis; photosystem II