Zhang, XiaoXiaoFarah, NadyaRolston, LauraEricsson, Daniel J.Catanzariti, Ann-MareeBernoux, MaudVe, ThomasBendak, KaterinaChen, ChunhongMackay, Joel P.Lawrence, Gregory J.Hardham, AdrienneEllis, Jeffrey G.Williams, SimonDodds, Peter N.Jones, DavidKobe, Bostjan2021-05-122021-05-121464-6722http://hdl.handle.net/1885/232677The effector protein AvrP is secreted by the flax rust fungal pathogen (Melampsora lini) and recognized specifically by the flax (Linum usitatissimum) P disease resistance protein, leading to effector‐triggered immunity. To investigate the biological function of this effector and the mechanisms of specific recognition by the P resistance protein, we determined the crystal structure of AvrP. The structure reveals an elongated zinc‐finger‐like structure with a novel interleaved zinc‐binding topology. The residues responsible for zinc binding are conserved in AvrP effector variants and mutations of these motifs result in a loss of P‐mediated recognition. The first zinc‐coordinating region of the structure displays a positively charged surface and shows some limited similarities to nucleic acid‐binding and chromatin‐associated proteins. We show that the majority of the AvrP protein accumulates in the plant nucleus when transiently expressed in Nicotiana benthamiana cells, suggesting a nuclear pathogenic function. Polymorphic residues in AvrP and its allelic variants map to the protein surface and could be associated with differences in recognition specificity. Several point mutations of residues on the non‐conserved surface patch result in a loss of recognition by P, suggesting that these residues are required for recognition.This research was supported by Australian Research Council (ARC) Discovery Projects DP120100685, DP130104098 and DP160102244. XZ was a recipient of an ANZ Trustees PhD Scholarship for Medical Research in Queensland. BK is a National Health and Medical Research Council (NHMRC) Principal Research Fellow (1003325 and 1110971). MB was a recipient of an ARC Discovery Early Career Research Award (DE130101292).application/pdfen-AU© 2017 BSPP and John Wiley & Songs Ltdhttps://creativecommons.org/licenses/by-nc-nd/4.0/crystal structureeffector-triggered immunityflax rust (Melampsora lini) effectorNLR [nucleotide-binding and oligomerization domain (NOD)-like receptor, nucleotide-binding/ leucine-rich repeat receptor]nuclear localizationplant disease resistancezinc finger2017-11-1610.1111/mpp.125972022-08-07Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)