Isolation and amino acid sequence of two new PR-4 proteins from wheat

We have purified and characterized two new pathogenesis-related (PR) protei ns from wheat belonging to the PR-4 family. We named the proteins wheatwin3 and wheatwin4 in analogy with the previously characterized wheatwin1 and w heatwin2. Their isoelectric points were 7.1 and 8.4, respectively, We deter mined the complete amino acid sequence of both proteins by a rapid approach based on the knowledge of the primary structures of the homologous wheatwi n1 and wheatwin2. Wheatwin3 differs from wheatwin1 in one substitution at p osition 88, while wheatwin4 differs from wheatwin2 in one substitution at p osition 78. The secondary structure and solvent accessibility of these resi dues were determined on the three-dimensional model of wheatwin1. Residue 8 8 was very accessible and was located in a flexible region. Preliminary res ults indicate that, like wheatwin1 and wheatwin2, wheatwin3 and wheatwin4 h ave antifungal activity.