title: Ca2+ signaling by plant Arabidopsis thaliana Pep peptides depends on AtPepR1, a receptor with guanylyl cyclase activity, and cGMP-activated Ca2+ channels.
abstract: A family of peptide signaling molecules (AtPeps) and their plasma membrane receptor AtPepR1 are known to act in pathogen-defense signaling cascades in plants. Little is currently known about the molecular mechanisms that link these signaling peptides and their receptor, a leucine-rich repeat receptor-like kinase, to downstream pathogen-defense responses. We identify some cellular activities of these molecules that provide the context for a model for their action in signaling cascades. AtPeps activate plasma membrane inwardly conducting Ca(2+) permeable channels in mesophyll cells, resulting in cytosolic Ca(2+) elevation. This activity is dependent on their receptor as well as a cyclic nucleotide-gated channel (CNGC2). We also show that the leucine-rich repeat receptor-like kinase receptor AtPepR1 has guanylyl cyclase activity, generating cGMP from GTP, and that cGMP can activate CNGC2-dependent cytosolic Ca(2+) elevation. AtPep-dependent expression of pathogen-defense genes (PDF1.2, MPK3, and WRKY33) is mediated by the Ca(2+) signaling pathway associated with AtPep peptides and their receptor. The work presented here indicates that extracellular AtPeps, which can act as danger-associated molecular patterns, signal by interaction with their receptor, AtPepR1, a plasma membrane protein that can generate cGMP. Downstream from AtPep and AtPepR1 in a signaling cascade, the cGMP-activated channel CNGC2 is involved in AtPep- and AtPepR1-dependent inward Ca(2+) conductance and resulting cytosolic Ca(2+) elevation. The signaling cascade initiated by AtPeps leads to expression of pathogen-defense genes in a Ca(2+)-dependent manner.
authors.affiliation: College of Life Science, Inner Mongolia University, Hohhot, Inner Mongolia 010021, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Qi
authors.forename: Rajeev
authors.initials: R
authors.lastname: Verma
authors.forename: Chris
authors.initials: C
authors.lastname: Gehring
authors.forename: Yube
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Yichen
authors.initials: Y
authors.lastname: Zhao
authors.forename: Clarence A
authors.initials: CA
authors.lastname: Ryan
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Berkowitz
mesh_terms: D017360:Arabidopsis / Q000276:immunology*; D029681:Arabidopsis Proteins / Q000276:immunology / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000276:immunology / Q000502:physiology*; D003600:Cytosol; D006162:Guanylate Cyclase / Q000378:metabolism; D007109:Immunity; D011956:Receptors, Cell Surface / Q000276:immunology / Q000502:physiology*; D015534:Trans-Activators / Q000276:immunology / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D002118:Calcium; D054815:Cyclic Nucleotide-Gated Cation Channels; D006162:Guanylate Cyclase; D011956:Receptors, Cell Surface; D015534:Trans-Activators; C518228:CNGC2 protein, Arabidopsis; C512592:PEPR1 protein, Arabidopsis; C512590:At5g64900 protein, Arabidopsis