title: Plasma membrane calcium ATPases are important components of receptor-mediated signaling in plant immune responses and development.
abstract: Plasma membrane-resident receptor kinases (RKs) initiate signaling pathways important for plant immunity and development. In Arabidopsis (Arabidopsis thaliana), the receptor for the elicitor-active peptide epitope of bacterial flagellin, flg22, is encoded by FLAGELLIN SENSING2 (FLS2), which promotes plant immunity. Despite its relevance, the molecular components regulating FLS2-mediated signaling remain largely unknown. We show that plasma membrane ARABIDOPSIS-AUTOINHIBITED Ca(2+)-ATPase (ACA8) forms a complex with FLS2 in planta. ACA8 and its closest homolog ACA10 are required for limiting the growth of virulent bacteria. One of the earliest flg22 responses is the transient increase of cytosolic Ca(2+) ions, which is crucial for many of the well-described downstream responses (e.g. generation of reactive oxygen species and the transcriptional activation of defense-associated genes). Mutant aca8 aca10 plants show decreased flg22-induced Ca(2+) and reactive oxygen species bursts and exhibit altered transcriptional reprogramming. In particular, mitogen-activated protein kinase-dependent flg22-induced gene expression is elevated, whereas calcium-dependent protein kinase-dependent flg22-induced gene expression is reduced. These results demonstrate that the fine regulation of Ca(2+) fluxes across the plasma membrane is critical for the coordination of the downstream microbe-associated molecular pattern responses and suggest a mechanistic link between the FLS2 receptor complex and signaling kinases via the secondary messenger Ca(2+). ACA8 also interacts with other RKs such as BRI1 and CLV1 known to regulate plant development, and both aca8 and aca10 mutants show morphological phenotypes, suggesting additional roles for ACA8 and ACA10 in developmental processes. Thus, Ca(2+) ATPases appear to represent general regulatory components of RK-mediated signaling pathways.
authors.affiliation: Max-Planck-Institute for Plant Breeding Research, 50829 Cologne, Germany.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Frei dit Frey
authors.forename: Malick
authors.initials: M
authors.lastname: Mbengue
authors.forename: Mark
authors.initials: M
authors.lastname: Kwaaitaal
authors.forename: Lisette
authors.initials: L
authors.lastname: Nitsch
authors.forename: Denise
authors.initials: D
authors.lastname: Altenbach
authors.forename: Heidrun
authors.initials: H
authors.lastname: Häweker
authors.forename: Rosa
authors.initials: R
authors.lastname: Lozano-Duran
authors.forename: Maria Fransiska
authors.initials: MF
authors.lastname: Njo
authors.forename: Tom
authors.initials: T
authors.lastname: Beeckman
authors.forename: Bruno
authors.initials: B
authors.lastname: Huettel
authors.forename: Jan Willem
authors.initials: JW
authors.lastname: Borst
authors.forename: Ralph
authors.initials: R
authors.lastname: Panstruga
authors.forename: Silke
authors.initials: S
authors.lastname: Robatzek
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D018506:Gene Expression Regulation, Plant; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D057865:Plant Immunity; D025941:Protein Interaction Mapping; D011494:Protein Kinases / Q000378:metabolism; D044224:Pseudomonas syringae / Q000276:immunology / Q000472:pathogenicity; D017382:Reactive Oxygen Species; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D017382:Reactive Oxygen Species; D011494:Protein Kinases; C411853:FLS2 protein, Arabidopsis; C529222:ACA10 protein, Arabidopsis; C508150:Aca8 protein, Arabidopsis; D000252:Calcium-Transporting ATPases; D002118:Calcium