title: Tools and Strategies to Match Peptide-Ligand Receptor Pairs.
abstract: Peptide signals have emerged as an important class of regulators in cell-to-cell communication in plants. Several families of small, secreted proteins with a conserved C-terminal Pro-rich motif have been identified as functional peptide signals in Arabidopsis thaliana. These proteins are presumed to be trimmed proteolytically and undergo posttranslational modifications, such as hydroxylation of Pro residues and glycosylation, to form mature, bioactive signals. Identification and matching of such ligands with their respective receptors remains a major challenge since the genes encoding them often show redundancy and low expression restricted to a few cells or particular developmental stages. To overcome these difficulties, we propose the use of ectopic expression of receptor genes in suitable plant cells like Nicotiana benthamiana for testing ligand candidates in receptor output assays and in binding studies. As an example, we used the IDA peptide HAE/HSL2 receptor signaling system known to regulate floral organ abscission. We demonstrate that the oxidative burst response can be employed as readout for receptor activation by synthetic peptides and that a new, highly sensitive, nonradioactive labeling approach can be used to reveal a direct correlation between peptide activity and receptor affinity. We suggest that these approaches will be of broad value for the field of ligand-receptor studies in plants.
authors.affiliation: Department of Biosciences, University of Oslo, N-0316 Oslo, Norway m.a.butenko@ibv.uio.no.
authors.forename: Melinka A
authors.initials: MA
authors.lastname: Butenko
authors.affiliation: Department of Biosciences, University of Oslo, N-0316 Oslo, Norway.
authors.forename: Mari
authors.initials: M
authors.lastname: Wildhagen
authors.affiliation: Zentrum für Molekularbiologie der Pflanzen, University Tübingen, 72076 Tübingen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Albert
authors.affiliation: Zentrum für Molekularbiologie der Pflanzen, University Tübingen, 72076 Tübingen, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Jehle
authors.affiliation: Medizinisch-Naturwissenschaftliches Forschungszentrum, 72074 Tübingen, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Kalbacher
authors.affiliation: Department of Biosciences, University of Oslo, N-0316 Oslo, Norway.
authors.forename: Reidunn B
authors.initials: RB
authors.lastname: Aalen
authors.affiliation: Zentrum für Molekularbiologie der Pflanzen, University Tübingen, 72076 Tübingen, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Felix