Characterization of the cryptogein binding sites on plant plasma membranes

• Published in: The Journal of biological chemistry 1999-12, Vol.274 (49), p.34699-34705
• Main Authors: Bourque, S, Binet, M.N, Ponchet, M, Pugin, A, Lebrun-Garcia, A
• Format: Article
• Language: English
• Subjects: Acer pseudoplatanus; Algal Proteins; Arabidopsis - chemistry; Arabidopsis - metabolism; Arabidopsis thaliana; Bacterial Proteins; Bacterial Toxins - pharmacology; Binding Sites; Binding, Competitive; Cell Membrane - chemistry; Cell Membrane - metabolism; Cross-Linking Reagents - metabolism; defense mechanisms; Fungal Proteins - chemistry; Fungal Proteins - isolation & purification; glycoproteins; Glycoside Hydrolases - metabolism; Kinetics; Life Sciences; Membrane Proteins - chemistry; Membrane Proteins - metabolism; molecular weight; Nicotiana - metabolism; Nicotiana tabacum; Periodic Acid - metabolism; Phytophthora cryptogea; Plant Proteins - chemistry; Plant Proteins - metabolism; Plants, Toxic; plasma membrane; Protein Binding; proteins; receptors; Time Factors
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.49.34699

Cryptogein is a 98-amino acid proteinaceous elicitor of tobacco defense reactions. Specific binding of cryptogein to high affinity binding sites on tobacco plasma membranes has been previously reported ( K d = 2 n m ; number of binding sites: 220 fmol/mg of protein). In this study, biochemical characterization of cryptogein binding sites reveals that they correspond to a plasma membrane glycoprotein(s) with an N -linked carbohydrate moiety, which is involved in cryptogein binding. Radiation inactivation experiments performed on tobacco plasma membrane preparations indicated that cryptogein bound specifically to a plasma membrane component with an apparent functional molecular mass of 193 kDa. Moreover, using the homobifunctional cross-linking reagent disuccinimidyl suberate and tobacco plasma membranes incubated with 125 I-cryptogein, we identified, after SDS-polyacrylamide gel electrophoresis and autoradiography, two 125 I-cryptogein linked N -glycoproteins of about 162 and 50 kDa. Similar results were obtained using Arabidopsis thaliana and Acer pseudoplatanus plasma membrane preparations, whereas cryptogein did not induce any effects on the corresponding cell suspensions. These results suggest that either cryptogein binds to nonfunctional binding sites, homologues to those present in tobacco plasma membranes, or that a protein involved in signal transduction after cryptogein recognition is absent or inactive in both A. pseudoplatanus and A. thaliana .