Phytophtora infestans AVR2 effector escapes R2 recognition through effector disordering.

Intrinsic disorder is a common structural characteristic of proteins and a central player in the biochemical processes of species. However, the role of intrinsic disorder in the evolution of plant-pathogen interactions is rarely investigated. Here we explored the role of intrinsic disorder in the development of the pathogenicity in the RXLR AVR2 effector of Phytophthora infestans. We found AVR2 exhibited high nucleotide diversity generated by point mutation, early-termination, altered start codon, deletion/insertion and intragenic recombination and is predicted to be an intrinsically disordered protein. AVR2 amino acid sequences conferring a virulent phenotype had a higher disorder tendency in both the N-terminal and C-terminal regions compared to sequences conferring an avirulent phenotype. In addition, we also found virulent AVR2 mutants gained 1-2 short linear interaction motifs (SLiMs), the critical components of disordered proteins required for protein-protein interactions. Furthermore, virulent AVR2 mutants were predicted to be unstable and have a short protein half-life. Taken together, these results support the notion that intrinsic disorder is important for the effector function of pathogens and demonstrate that SLiM mediated protein-protein interaction in C-terminal effector domain might contribute greatly to the evasion of R protein detection in P. infestans.