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Publications - Stress and Develop Biology

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Publications

Nennstiel, D.; Scheel, D.; Nürnberger, T.; Characterization and partial purification of an oligopeptide elicitor receptor from parsley (Petroselinum crispum) FEBS Lett. 431, 405-410, (1998) DOI: 10.1016/S0014-5793(98)00800-X

Parsley cells recognize the fungal phytopathogen Phytophthora sojae through a plasma membrane receptor. A 13 amino acid oligopeptide fragment (Pep-13) of a 42 kDa fungal cell wall glycoprotein was shown to bind to the receptor and stimulate a complex defense response in cultured parsley cells. The Pep-13 binding site solubilized from parsley microsomal membranes by non-ionic detergents exhibited the same ligand affinity and ligand specificity as the membrane-bound receptor. Chemical crosslinking and photoaffinity labeling assays with [125I]Pep-13 revealed that a monomeric 100 kDa integral plasma membrane protein is sufficient for ligand binding and may thus constitute the ligand binding domain of the receptor. Ligand affinity chromatography of solubilized microsomal membrane protein on immobilized Pep-13 yielded a 5000-fold enrichment of specific receptor activity.
Publications

Nürnberger, T.; Nennstiel, D.; Hahlbrock, K.; Scheel, D.; Covalent cross-linking of the Phytophthora megasperma oligopeptide elicitor to its receptor in parsley membranes. Proc. Natl. Acad. Sci. U.S.A. 92, 2338-2342, (1995) DOI: 10.1073/pnas.92.6.2338

An oligopeptide elicitor from Phytophthora megasperma f.sp. glycinea (Pep-13) that induces phytoalexin accumulation in cultured parsley cells was radioiodinated and chemically cross-linked to its binding site in microsomal and plasma membrane preparations with each of three homobifunctional reagents. Analysis by SDS/PAGE and autoradiography of solubilized membrane proteins demonstrated labeling of a 91-kDa protein, regardless of which reagent was used. Cross-linking of this protein was prevented by addition of excess unlabeled Pep-13. The competitor concentration found to half-maximally reduce the intensity of the cross-linked band was 6 nM, which is in good agreement with the IC50 value of 4.7 nM, obtained from ligand binding assays. No crosslinking of 125I-labeled Pep-13 was observed by using microsomal membranes from three other plant species, indicating species-specific occurrence of the binding site. Coupling of 125I-Pep-13 to the parsley 91-kDa protein required the same structural elements within the ligand as was recently reported for binding of 125I-Pep-13 to parsley microsomes, elicitor-induced stimulation of ion fluxes across the plasma membrane, the oxidative burst, the expression of defense-related genes, and phytoalexin production. These findings suggest that the 91-kDa protein identified in parsley membranes is the oligopeptide elicitor receptor mediating activation of a multicomponent defense response.
Publications

Nürnberger, T.; Nennstiel, D.; Jabs, T.; Sacks, W. R.; Hahlbrock, K.; Scheel, D.; High affinity binding of a fungal oligopeptide elicitor to parsley plasma membranes triggers multiple defense responses Cell 78, 449-460, (1994) DOI: 10.1016/0092-8674(94)90423-5

An oligopeptide of 13 amino acids (Pep-13) identified within a 42 kDa glycoprotein elicitor from P. megasperma was shown to be necessary and sufficient to stimulate a complex defense response in parsley cells comprising H+/Ca2+ influxes, K+/Cl− effluxes, an oxidative burst, defense-related gene activation, and phytoalexin formation. Binding of radiolabeled Pep-13 to parsley microsomes and protoplasts was specific, reversible, and saturable. Identical structural features of Pep-13 were found to be responsible for specific binding and initiation of all plant responses analyzed. The high affinity binding site recognizing the peptide ligand (KD = 2.4 nM) may therefore represent a novel class of receptors in plants, and the rapidly induced ion fluxes may constitute elements of the signal transduction cascade triggering pathogen defense in plants.
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