title: LSU network hubs integrate abiotic and biotic stress responses via interaction with the superoxide dismutase FSD2.
abstract: In natural environments, plants often experience different stresses simultaneously, and adverse abiotic conditions can weaken the plant immune system. Interactome mapping revealed that the LOW SULPHUR UPREGULATED (LSU) proteins are hubs in an Arabidopsis protein interaction network that are targeted by virulence effectors from evolutionarily diverse pathogens. Here we show that LSU proteins are up-regulated in several abiotic and biotic stress conditions, such as nutrient depletion or salt stress, by both transcriptional and post-translational mechanisms. Interference with LSU expression prevents chloroplastic reactive oxygen species (ROS) production and proper stomatal closure during sulphur stress. We demonstrate that LSU1 interacts with the chloroplastic superoxide dismutase FSD2 and stimulates its enzymatic activity in vivo and in vitro. Pseudomonas syringae virulence effectors interfere with this interaction and preclude re-localization of LSU1 to chloroplasts. We demonstrate that reduced LSU levels cause a moderately enhanced disease susceptibility in plants exposed to abiotic stresses such as nutrient deficiency, high salinity, or heavy metal toxicity, whereas LSU1 overexpression confers significant disease resistance in several of these conditions. Our data suggest that the network hub LSU1 plays an important role in co-ordinating plant immune responses across a spectrum of abiotic stress conditions.
authors.affiliation: Technische Universität München (TUM), School for Life Sciences Weihenstephan (WZW), Plant Systems Biology, Emil-Ramann-Straße, 4, D-85354 Freising, Germany.
authors.forename: Antoni
authors.initials: A
authors.lastname: Garcia-Molina
authors.affiliation: Technische Universität München (TUM), School for Life Sciences Weihenstephan (WZW), Plant Systems Biology, Emil-Ramann-Straße, 4, D-85354 Freising, Germany.
authors.forename: Melina
authors.initials: M
authors.lastname: Altmann
authors.affiliation: Technische Universität München (TUM), School for Life Sciences Weihenstephan (WZW), Plant Systems Biology, Emil-Ramann-Straße, 4, D-85354 Freising, Germany.
authors.forename: Angela
authors.initials: A
authors.lastname: Alkofer
authors.affiliation: Howard Hughes Medical Institute and Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Petra M
authors.initials: PM
authors.lastname: Epple
authors.affiliation: BASF Plant Science LP, Research Triangle Park, NC 27709, USA.
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Dangl
authors.affiliation: Institute of Network Biology (INET), Helmholtz Zentrum München (HMGU), German Research Center for Environmental Health, 85764 Neuherberg, Germany.|Department of Microbe-Host Interactions, Ludwig-Maximilians-Universität München (LMU Munich), Planegg-Martinsried, Germany.
authors.forename: Pascal
authors.initials: P
authors.lastname: Falter-Braun
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060467:Disease Resistance / Q000276:immunology; D018506:Gene Expression Regulation, Plant; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D044224:Pseudomonas syringae / Q000502:physiology*; D013312:Stress, Physiological; D013455:Sulfur / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C000624494:LSU1 protein, Arabidopsis; D009687:Nuclear Proteins; D013455:Sulfur; D013482:Superoxide Dismutase
keywords: Abiotic stress; Arabidopsis thaliana; LOW SULPHUR UPREGULATED; LSU1; biotic stress; combinatorial stress