Hevea brasiliensis prohevein possesses a conserved C-terminal domain with amyloid-like properties in vitro

• Hevein and its precursor display a strong toxicity when expressed in E. coli.
• The C-terminal domain of prohevein has amyloid properties.
• Prohevein presents no interactions with hydrophobic interfaces.
• Prohevein has also agglutination and chitin-binding properties.
• Prohevein homologues are predicted to have amyloid propensity in their C-terminus.

Prohevein is a wound-induced protein and a main allergen from latex of Hevea brasiliensis (rubber tree). This 187 amino-acid protein is cleaved in two fragments: a N-terminal 43 amino-acids called hevein, a lectin bearing a chitin-binding motif with antifungal properties and a C-terminal domain (C-ter) far less characterized. We provide here new insights on the characteristics of prohevein, hevein and C-terminal domain. Using complementary biochemical (ThT/CR/chitin binding, agglutination) and structural (modeling, ATR-FTIR, TEM, WAXS) approaches, we show that this domain clearly displays all the characteristics of an amyloid-like proteins in vitro, that could confer agglutination activity in synergy with its chitin-binding activity. Additionally, this C-ter domain is highly conserved and present in numerous plant prohevein-like proteins or pathogenesis-related (PR and WIN) proteins. This could be the hallmark of the eventual presence of proteins with amyloid properties in plants, that could potentially play a role in defense through aggregation properties.

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