title: Deletion of the gene family of small chlorophyll-binding proteins (ScpABCDE) offsets C/N homeostasis in Synechocystis PCC 6803.
abstract: In the family of chlorophyll binding proteins, single helix small CAB-like proteins (SCPs) are found in all organisms performing oxygenic photosynthesis. Here, we investigated the function of these stress-inducible proteins in the cyanobacterium Synechocystis sp. PCC 6803. We compared physiological, proteome and transcriptome traits of a Photosystem I (PSI) deletion strain, which constitutively induces SCPs, and a PSI-less/ScpABCDE(-) without SCPs. The SCP mutant cells were larger in size, showed irregular thylakoid structure and differed in cell-surface morphology. Deletion of scp genes strongly affected the carbon (C) and nitrogen (N) balance, resulting in accumulation of carbohydrates and a decrease in N-rich compounds (proteins and chlorophyll). Data from transcriptomic and metabolomic experiments revealed a role of SCPs in the control of chlorophyll biosynthesis. Additionally, SCPs diminished formation of reactive oxygen species, thereby preventing damage within Photosystem II. We conclude that the lack of SCP-function to remove free chlorophyll under stress conditions has a large impact on the metabolism of the entire cell.
authors.affiliation: Department of Chemistry, Umeå University, SE 90187 Umeå, Sweden.
authors.forename: Tania
authors.initials: T
authors.lastname: Tibiletti
authors.affiliation: Department of Chemistry, Umeå University, SE 90187 Umeå, Sweden.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Hernández-Prieto
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, Netherlands.
authors.forename: Hans C P
authors.initials: HC
authors.lastname: Matthijs
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-3102, USA.
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Niyogi
authors.affiliation: Department of Chemistry, Umeå University, SE 90187 Umeå, Sweden. Electronic address: Christiane.Funk@chem.umu.se.
authors.forename: Christiane
authors.initials: C
authors.lastname: Funk
mesh_terms: D002244:Carbon / Q000378:metabolism*; D061146:Chlorophyll Binding Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D006706:Homeostasis; D055432:Metabolomics; D009584:Nitrogen / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D046939:Synechocystis / Q000378:metabolism*
chemical_list: D061146:Chlorophyll Binding Proteins; D017382:Reactive Oxygen Species; D002244:Carbon; D009584:Nitrogen
keywords: C/N metabolism; Cyanobacterium (Synechocystis sp. strain PCC 6803); High light protection; Pleiotropic effects; Small chlorophyll-proteins