Sequences of acidic and basic elicitin isoforms secreted by Phytophthora megasperma megasperma

Abstract

Elicitins are toxic proteins secreted by Phytophthora spp. responsible for the incompatible reaction and systemic leaf necroses on tobacco. We found that Phytophthora megasperma megasperma produces two elicitin isoforms, each belonging to a different physico-chemical class, although the β elicitin was less toxic than other β ones. These 98 residue proteins were purified, sequenced and compared with other known elicitins. In addition to the point mutation already known to correlate with the differences in necrotic activities between α and β isoforms, we found another region of the molecule likely to be involved in the regulation of the toxicity.