Amino acid sequence of the alpha-elicitin secreted by Phytophthora cactorum.

Elicitins are toxic, signalling proteins secreted by Phytophthora spp. responsible for the incompatible reaction and systemic leaf necroses. We have sequenced the least toxic known elicitin, which is secreted by Phytophthora cactorum and belongs to the alpha-elicitin class. This 98 residue sequence was compared to eight other known elicitins. In addition to the point mutation already observed to correlate with the differences in necrotic activities, we confirmed the existence of amino acid changes in the central region of the molecule, comparable to those already shown in one of the Phytophthora megasperma megasperma elicitins, to be correlated with toxicity.