title: Low-carbon acclimation in carboxysome-less and photorespiratory mutants of the cyanobacterium Synechocystis sp. strain PCC 6803.
abstract: Using metabolic and transcriptomic phenotyping, we studied acclimation of cyanobacteria to low inorganic carbon (LC) conditions and the requirements for coordinated alteration of metabolism and gene expression. To analyse possible metabolic signals for LC sensing and compensating reactions, the carboxysome-less mutant ΔccmM and the photorespiratory mutant ΔglcD1/D2 were compared with wild-type (WT) Synechocystis. Metabolic phenotyping revealed accumulation of 2-phosphoglycolate (2PG) in ΔccmM and of glycolate in ΔglcD1/D2 in LC- but also in high inorganic carbon (HC)-grown mutant cells. The accumulation of photorespiratory metabolites provided evidence for the oxygenase activity of RubisCO at HC. The global gene expression patterns of HC-grown ΔccmM and ΔglcD1/D2 showed differential expression of many genes involved in photosynthesis, high-light stress and N assimilation. In contrast, the transcripts of LC-specific genes, such as those for inorganic carbon transporters and components of the carbon-concentrating mechanism (CCM), remained unchanged in HC cells. After a shift to LC, ΔglcD1/D2 and WT cells displayed induction of many of the LC-inducible genes, whereas ΔccmM lacked similar changes in expression. From the coincidence of the presence of 2PG in ΔccmM without CCM induction and of glycolate in ΔglcD1/D2 with CCM induction, we regard a direct role for 2PG as a metabolic signal for the induction of CCM during LC acclimation as less likely. Instead, our data suggest a potential role for glycolate as a signal molecule for enhanced expression of CCM genes.
authors.affiliation: Universität Rostock, Institut für Biowissenschaften, Pflanzenphysiologie, Albert-Einstein-Str. 3, D-18059 Rostock, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Hackenberg
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Golm, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Huege
authors.affiliation: Universität Rostock, Institut für Biowissenschaften, Pflanzenphysiologie, Albert-Einstein-Str. 3, D-18059 Rostock, Germany.
authors.forename: Annerose
authors.initials: A
authors.lastname: Engelhardt
authors.affiliation: Microarray Department, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands.
authors.forename: Floyd
authors.initials: F
authors.lastname: Wittink
authors.affiliation: Universität Rostock, Institut für Pathologie, Elektronenmikroskopisches Zentrum, Strempelstr. 14, D-18055 Rostock, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Laue
authors.affiliation: Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands.
authors.forename: Hans C P
authors.initials: HCP
authors.lastname: Matthijs
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Golm, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Kopka
authors.affiliation: Universität Rostock, Institut für Biowissenschaften, Pflanzenphysiologie, Albert-Einstein-Str. 3, D-18059 Rostock, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Bauwe
authors.affiliation: Universität Rostock, Institut für Biowissenschaften, Pflanzenphysiologie, Albert-Einstein-Str. 3, D-18059 Rostock, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Hagemann
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002244:Carbon / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects; D008027:Light; D009154:Mutation; D010788:Photosynthesis / Q000528:radiation effects; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D001426:Bacterial Proteins; D002244:Carbon