title: Secondary metabolite from Nostoc XPORK14A inhibits  photosynthesis and growth of Synechocystis PCC 6803.
abstract: Screening of 55 different cyanobacterial strains revealed that an extract from Nostoc XPORK14A drastically modifies the amplitude and kinetics of chlorophyll a fluorescence induction of Synechocystis PCC6803 cells.After 2 d exposure to the Nostoc XPORK14A extract, Synechocystis PCC 6803 cells displayed reduced net photosynthetic activity and significantly modified electron transport properties of photosystem II under both light and dark conditions. However, the maximum oxidizable amount of P700 was not strongly affected. The extract also induced strong oxidative stress in Synechocystis PCC 6803 cells in both light and darkness. We identified the secondary metabolite of Nostoc XPORK14A causing these pronounced effects on Synechocystis cells. Mass spectrometry and nuclear magnetic resonance analyses revealed that this compound, designated as M22, has a non-peptide structure. We propose that M22 possesses a dualaction mechanism: firstly, by photogeneration of reactive oxygen species in the presence of light, which in turn affects the photosynthetic machinery of Synechocystis PCC 6803; and secondly, by altering the in vivo redox status of cells, possibly through inhibition of protein kinases.
authors.forename: Sumathy
authors.initials: S
authors.lastname: Shunmugam
authors.forename: Jouni
authors.initials: J
authors.lastname: Jokela
authors.forename: Matti
authors.initials: M
authors.lastname: Wahlsten
authors.forename: Natalia
authors.initials: N
authors.lastname: Battchikova
authors.lastname: Ateeq ur Rehman
authors.forename: Imre
authors.initials: I
authors.lastname: Vass
authors.forename: Maarit
authors.initials: M
authors.lastname: Karonen
authors.forename: Jari
authors.initials: J
authors.lastname: Sinkkonen
authors.forename: Perttu
authors.initials: P
authors.lastname: Permi
authors.forename: Kaarina
authors.initials: K
authors.lastname: Sivonen
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
authors.forename: Yagut
authors.initials: Y
authors.lastname: Allahverdiyeva
mesh_terms: D002457:Cell Extracts / Q000737:chemistry / Q000494:pharmacology; D002478:Cells, Cultured; D002734:Chlorophyll / Q000378:metabolism*; D000077194:Chlorophyll A; D004579:Electron Transport / Q000187:drug effects; D007700:Kinetics; D046937:Nostoc / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009792:Oceans and Seas; D018384:Oxidative Stress / Q000187:drug effects; D010788:Photosynthesis / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D046939:Synechocystis / Q000254:growth & development / Q000502:physiology*
chemical_list: D002457:Cell Extracts; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D000077194:Chlorophyll A