Poster: Plant Pathogen/Symbiont Interactions
Abs #
733: Lipid-binding form is a Key Conformation to Induce a Programmed Cell Death on Tobacco BY-2 Initiated by a Proteinaceous Elicitor of Cryptogein
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Presenter: |
Amano, Toyoki , sbtaman@ipc.shizuoka.ac.jp |
Authors | Amano, Toyoki (A) Hirasawa, Ken-ichi (A) Shioi, Yuzo (A) | | Affiliations: |
(A): Department of Biology and Geosciences, Faculty of Science, Shizuoka University
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Cryptogein, a proteinaceous elicitor secreted by Phytophthora cryptogea, induces a remarkable hypersensitive cell death in tobacco cells. This protein is a member of elicitin family. Elicitin is classified as two groups according to the strength of death induction properties, one is a weak elicitor of a-elicitin, and another is strong death inducer of b-elicitin. However, it has not been revealed what kinds of factor determine those death induction activities.
We analyzed two cryptogein mutants; one was a newly synthesized mutant of N93A whose 93rd Asn residue was exchanged to Ala, and K13V whose Lys at 13th was replaces to Val. We evaluated the effect of mutations in terms of extracellular alkalization, production of active oxygen species (AOS) and death progression. The mutation to N93A resulted in the reduction of activities to 71.0, 74.6 and 24.5% of original rates of extracellular alkalization, AOS production and death progression, respectively. In the case of K13V, mutation changed those rates to 114, 3.38 and 7.40%, respectively. Lipid binding activities of those mutants were analyzed by means of fluorogenic lipid of dehydroergosterol. The mutation to N93A and K13V changed its binding activity to 24.4% and 7.68%, respectively of wild type. These results indicate that the lipid-binding form was the only conformation to induce the AOS production and programmed cell death in plant. In addition to these findings, computer analysis revealed that those two conformations were significantly different in the surface structure. In this study, we discuss a mechanism of molecular recognition on the plant surface, and found that the lipid-binding form of cryptogein is a key conformation to induce a programmed cell death on plant cells.
