title: Host-induced bacterial cell wall decomposition mediates pattern-triggered immunity in Arabidopsis.
abstract: Peptidoglycans (PGNs) are immunogenic bacterial surface patterns that trigger immune activation in metazoans and plants. It is generally unknown how complex bacterial structures such as PGNs are perceived by plant pattern recognition receptors (PRRs) and whether host hydrolytic activities facilitate decomposition of bacterial matrices and generation of soluble PRR ligands. Here we show that Arabidopsis thaliana, upon bacterial infection or exposure to microbial patterns, produces a metazoan lysozyme-like hydrolase (lysozyme 1, LYS1). LYS1 activity releases soluble PGN fragments from insoluble bacterial cell walls and cleavage products are able to trigger responses typically associated with plant immunity. Importantly, LYS1 mutant genotypes exhibit super-susceptibility to bacterial infections similar to that observed on PGN receptor mutants. We propose that plants employ hydrolytic activities for the decomposition of complex bacterial structures, and that soluble pattern generation might aid PRR-mediated immune activation in cell layers adjacent to infection sites.
authors: Department of Plant Biochemistry, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
authors: Xiaokun
authors: X
authors: Liu
authors: Department of Plant Biochemistry, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
authors: Heini M
authors: HM
authors: Grabherr
authors: Department of Plant Biochemistry, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
authors: Roland
authors: R
authors: Willmann
authors: Department of Plant Biochemistry, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
authors: Dagmar
authors: D
authors: Kolb
authors: Department of Plant Biochemistry, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
authors: Frédéric
authors: F
authors: Brunner
authors: Department of Microbial Genetics, University of Tübingen, Tübingen, Germany.
authors: Ute
authors: U
authors: Bertsche
authors: Department of Microbial Genetics, University of Tübingen, Tübingen, Germany.
authors: Daniel
authors: D
authors: Kühner
authors: Proteome Center Tübingen, University of Tübingen, Tübingen, Germany.
authors: Mirita
authors: M
authors: Franz-Wachtel
authors: Medical and Natural Sciences Research Centre, University of Tübingen, Tübingen, Germany.
authors: Bushra
authors: B
authors: Amin
authors: Department of Plant Biochemistry, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
authors: Georg
authors: G
authors: Felix
authors: Wallon Centre for Industrial Biology, University of Liege-Gembloux Agro-Bio Tech, Gembloux, Belgium.
authors: Marc
authors: M
authors: Ongena
authors: Department of Plant Biochemistry, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
authors: Thorsten
authors: T
authors: Nürnberger
authors: Department of Plant Biochemistry, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
authors: Andrea A
authors: AA
authors: Gust
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D001419:Bacteria / Q000378:metabolism*; D001483:Base Sequence; D002473:Cell Wall / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006868:Hydrolysis; D008024:Ligands; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D010457:Peptidoglycan / Q000737:chemistry; D057865:Plant Immunity; D030821:Plants, Genetically Modified / Q000276:immunology / Q000382:microbiology; D012689:Sequence Homology, Nucleic Acid; D014026:Nicotiana / Q000235:genetics / Q000382:microbiology
chemical_list: D008024:Ligands; D010455:Peptides; D010457:Peptidoglycan; D009113:Muramidase
keywords: arabidopsis; glycan hydrolase; innate immunity; pattern-triggered immunity; peptidoglycan; plant biology; plant lysozyme