title: Mechanism of photoprotection in the cyanobacterial ancestor of plant antenna proteins.
abstract: Plants collect light for photosynthesis using light-harvesting complexes (LHCs)-an array of chlorophyll proteins that are able to reversibly switch from harvesting to energy-dissipation mode to prevent damage of the photosynthetic apparatus. LHC antennae as well as other members of the LHC superfamily evolved from cyanobacterial ancestors called high light-inducible proteins (Hlips). Here, we characterized a purified Hlip family member HliD isolated from the cyanobacterium Synechocystis sp. PCC 6803. We found that the HliD binds chlorophyll-a (Chl-a) and β-carotene and exhibits an energy-dissipative conformation. Using femtosecond spectroscopy, we demonstrated that the energy dissipation is achieved via direct energy transfer from a Chl-a Qy state to the β-carotene S1 state. We did not detect any cation of β-carotene that would accompany Chl-a quenching. These results provide proof of principle that this quenching mechanism operates in the LHC superfamily and also shed light on the photoprotective role of Hlips and the evolution of LHC antennae.
authors.affiliation: Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
authors.forename: Hristina
authors.initials: H
authors.lastname: Staleva
authors.affiliation: 1] Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic. [2] Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň, Czech Republic.
authors.forename: Josef
authors.identifier: 0000000345880382
authors.initials: J
authors.lastname: Komenda
authors.affiliation: 1] Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic. [2] Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň, Czech Republic.
authors.forename: Mahendra K
authors.initials: MK
authors.lastname: Shukla
authors.affiliation: Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
authors.forename: Václav
authors.initials: V
authors.lastname: Šlouf
authors.affiliation: 1] Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic. [2] Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň, Czech Republic.
authors.forename: Radek
authors.identifier: 0000000157686902
authors.initials: R
authors.lastname: Kaňa
authors.affiliation: 1] Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic. [2] Biology Centre, Institute of Plant Molecular Biology, Academy of Sciences of the Czech Republic, České Budějovice, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Polívka
authors.affiliation: 1] Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic. [2] Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň, Czech Republic.
authors.forename: Roman
authors.initials: R
authors.lastname: Sobotka
mesh_terms: D002338:Carotenoids / Q000737:chemistry*; D002734:Chlorophyll / Q000737:chemistry*; D000077194:Chlorophyll A; D000458:Cyanobacteria / Q000378:metabolism*; D004583:Electrons; D004735:Energy Transfer; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism; D055668:Photochemical Processes; D010788:Photosynthesis; D010940:Plant Proteins / Q000737:chemistry*; D010944:Plants / Q000378:metabolism; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D046939:Synechocystis / Q000378:metabolism; D019207:beta Carotene / Q000737:chemistry*
chemical_list: D045342:Light-Harvesting Protein Complexes; D010940:Plant Proteins; D019207:beta Carotene; D002734:Chlorophyll; D002338:Carotenoids; C041635:alpha-carotene; D000077194:Chlorophyll A