title: A bestrophin-like protein modulates the proton motive force across the thylakoid membrane in Arabidopsis.
abstract: During photosynthesis, photosynthetic electron transport generates a proton motive force (pmf) across the thylakoid membrane, which is used for ATP biosynthesis via ATP synthase in the chloroplast. The pmf is composed of an electric potential (ΔΨ) and an osmotic component (ΔpH). Partitioning between these components in chloroplasts is strictly regulated in response to fluctuating environments. However, our knowledge of the molecular mechanisms that regulate pmf partitioning is limited. Here, we report a bestrophin-like protein (AtBest), which is critical for pmf partitioning. While the ΔpH component was slightly reduced in atbest, the ΔΨ component was much greater in this mutant than in the wild type, resulting in less efficient activation of nonphotochemical quenching (NPQ) upon both illumination and a shift from low light to high light. Although no visible phenotype was observed in the atbest mutant in the greenhouse, this mutant exhibited stronger photoinhibition than the wild type when grown in the field. AtBest belongs to the bestrophin family proteins, which are believed to function as chloride (Cl-) channels. Thus, our findings reveal an important Cl-channel required for ion transport and homeostasis across the thylakoid membrane in higher plants. These processes are essential for fine-tuning photosynthesis under fluctuating environmental conditions.
authors.affiliation: Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhikun
authors.initials: Z
authors.lastname: Duan
authors.affiliation: Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Fanna
authors.initials: F
authors.lastname: Kong
authors.affiliation: Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Li
authors.affiliation: Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. penglianwei@ibcas.ac.cn.
authors.forename: Lianwei
authors.initials: L
authors.lastname: Peng
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D010788:Photosynthesis / Q000502:physiology; D018892:Proton-Motive Force / Q000502:physiology; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins
keywords: Bestrophin; Cl− channel; photoprotection; photosynthesis; proton motive force