title: The calcium-dependent protein kinase CPK28 negatively regulates the BIK1-mediated PAMP-induced calcium burst.
abstract: Plants are protected from microbial infection by a robust immune system. Two of the earliest responses mediated by surface-localized immune receptors include an increase in cytosolic calcium (Ca(2+)) and a burst of apoplastic reactive oxygen species (ROS). The Arabidopsis plasma membrane-associated cytoplasmic kinase BIK1 is an immediate convergent substrate of multiple surface-localized immune receptors that is genetically required for the PAMP-induced Ca(2+) burst and directly regulates ROS production catalyzed by the NADPH oxidase RBOHD. We recently demonstrated that Arabidopsis plants maintain an optimal level of BIK1 through a process of continuous degradation regulated by the Ca(2+)-dependent protein kinase CPK28. cpk28 mutants accumulate more BIK1 protein and display enhanced immune signaling, while plants over-expressing CPK28 accumulate less BIK1 protein and display impaired immune signaling. Here, we show that CPK28 additionally contributes to the PAMP-induced Ca(2+) burst, supporting its role as a negative regulator of BIK1.
authors.affiliation: a The Sainsbury Laboratory; Norwich Research Park ; Norwich , United Kingdom.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Monaghan
authors.forename: Susanne
authors.initials: S
authors.lastname: Matschi
authors.forename: Tina
authors.initials: T
authors.lastname: Romeis
authors.forename: Cyril
authors.initials: C
authors.lastname: Zipfel
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000276:immunology; D029681:Arabidopsis Proteins / Q000378:metabolism*; D020013:Calcium Signaling; D000069452:Pathogen-Associated Molecular Pattern Molecules / Q000378:metabolism*; D057865:Plant Immunity; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D029681:Arabidopsis Proteins; D000069452:Pathogen-Associated Molecular Pattern Molecules; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C509522:BIK1 protein, Arabidopsis
keywords: BIK1; CPK28; PAMP-triggered immunity; arabidopsis; calcium; phosphorylation; signal transduction