Abstract
Cryptogein is known as a proteinaceous elicitor, which induces HR in tobacco cell. We generated cryptogein mutants (K13V and N93A) and compared the biological activities of external alkalization and death progression. The quantitative results exhibited that N93A declined both the external alkalization and death induction activity. In the case of K13V, the death progression was inhibited to less than 10% of original activity, although its external alkalization retained normal.
The cryptogein-sterol complex is a key component of death induction. Using a fluorescent probe, dehydroergosterol, we examined the sterol binding activity of these mutants. From the results, we found that K13V lost its binding ability, and N93A retained a half of the original ability. These results suggest that cryptogein requires a sterol binding to induce an efficient death reaction on plant cell, although the external alkalization does not require the sterol binding inside of cryptogein molecule.
