title: Light Modulates the Biosynthesis and Organization of Cyanobacterial Carbon Fixation Machinery through Photosynthetic Electron Flow.
abstract: Cyanobacteria have evolved effective adaptive mechanisms to improve photosynthesis and CO2 fixation. The central CO2-fixing machinery is the carboxysome, which is composed of an icosahedral proteinaceous shell encapsulating the key carbon fixation enzyme, Rubisco, in the interior. Controlled biosynthesis and ordered organization of carboxysomes are vital to the CO2-fixing activity of cyanobacterial cells. However, little is known about how carboxysome biosynthesis and spatial positioning are physiologically regulated to adjust to dynamic changes in the environment. Here, we used fluorescence tagging and live-cell confocal fluorescence imaging to explore the biosynthesis and subcellular localization of β-carboxysomes within a model cyanobacterium, Synechococcus elongatus PCC7942, in response to light variation. We demonstrated that β-carboxysome biosynthesis is accelerated in response to increasing light intensity, thereby enhancing the carbon fixation activity of the cell. Inhibition of photosynthetic electron flow impairs the accumulation of carboxysomes, indicating a close coordination between β-carboxysome biogenesis and photosynthetic electron transport. Likewise, the spatial organization of carboxysomes in the cell correlates with the redox state of photosynthetic electron transport chain. This study provides essential knowledge for us to modulate the β-carboxysome biosynthesis and function in cyanobacteria. In translational terms, the knowledge is instrumental for design and synthetic engineering of functional carboxysomes into higher plants to improve photosynthesis performance and CO2 fixation.
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom (Y.S., S.C., Y.F., F.H., M.F., L.-N.L.); and Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom (S.B.).
authors.forename: Yaqi
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom (Y.S., S.C., Y.F., F.H., M.F., L.-N.L.); and Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom (S.B.).
authors.forename: Selene
authors.initials: S
authors.lastname: Casella
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom (Y.S., S.C., Y.F., F.H., M.F., L.-N.L.); and Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom (S.B.).
authors.forename: Yi
authors.identifier: 0000-0001-7944-3717
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom (Y.S., S.C., Y.F., F.H., M.F., L.-N.L.); and Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom (S.B.).
authors.forename: Fang
authors.identifier: 0000-0002-6618-3386
authors.initials: F
authors.lastname: Huang
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom (Y.S., S.C., Y.F., F.H., M.F., L.-N.L.); and Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom (S.B.).
authors.forename: Matthew
authors.identifier: 0000-0002-0578-388X
authors.initials: M
authors.lastname: Faulkner
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom (Y.S., S.C., Y.F., F.H., M.F., L.-N.L.); and Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom (S.B.).
authors.forename: Steve
authors.identifier: 0000-0003-2960-3334
authors.initials: S
authors.lastname: Barrett
authors.affiliation: Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom (Y.S., S.C., Y.F., F.H., M.F., L.-N.L.); and Department of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom (S.B.) luning.liu@liverpool.ac.uk.
authors.forename: Lu-Ning
authors.identifier: 0000-0002-8884-4819
authors.initials: LN
authors.lastname: Liu
mesh_terms: D057486:Carbon Cycle / Q000502:physiology*; D004237:Diuron / Q000494:pharmacology; D004579:Electron Transport; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008027:Light; D008856:Microscopy, Fluorescence / Q000379:methods; D030781:Organisms, Genetically Modified; D010788:Photosynthesis / Q000502:physiology*; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism; D046940:Synechococcus / Q000187:drug effects / Q000502:physiology*
chemical_list: D049452:Green Fluorescent Proteins; D004237:Diuron; D012273:Ribulose-Bisphosphate Carboxylase