N-glycosylation shields Phytophthora sojae apoplastic effector PsXEG1 from a specific host aspartic protease (Proc. Natl. Acad. Sci. USA)

Physicists say “for every reaction there is an equal and opposite reaction,” an expression that applies to the interactions between plants and pathogens as well. Here, Xia et al. have uncovered another layer in the “arms race” between soybeans and the oomycete pathogen Phytophthora sojae. PsXEG1 is an oomycete-produced plant cell wall-degrading xyloglucan-specific endoglucanase. Previous studies have identified a specific inhibitor of PsXEG1 enzymatic activity, produced by the plant cell to suppress the pathogen. Here, the authors have identified another plant strategy, the secretion of a very specific protease that targets PsXEG1. Not to be outdone, the pathogen blocks the plant protease by post-translationally modifying PsXEG1 through addition of a glycosyl group to an Asn residue (N-glycosylation), and this modification is necessary for the pathogen’s full virulence. Evolution truly is a wonderous process. (Summary by Mary Williams @PlantTeaching) Proc. Natl. Acad. Sci. USA 10.1073/pnas.2012149117