Exploiting effector - host interactions using TurboID-based proximity labeling

Abstract

AbstractPlant pathogens secrete effectors, which target host proteins to facilitate infection. TheUstilago maydiseffector UmSee1 is required for tumor formation in the leaf during infection of maize. UmSee1 interacts with maize SGT1 and blocks its phosphorylationin-vivo. In the absence of UmSee1,U. maydiscannot trigger tumor formation in the bundle sheath. However, it remains unclear which host processes are manipulated by UmSee1 and the UmSee1-SGT1 interaction to cause the observed phenotype. Proximity-dependent protein labeling involving the turbo biotin ligase tag (TurboID) for proximal labeling of proteins is a powerful tool for identifying the protein interactome. We have generated transgenicU. maydisthat secretes biotin ligase-fused See1 effector (UmSee1-TurboID-3HA) directly into maize cells. This approach, in combination with conventional co-immunoprecipitation allowed to identify additional UmSee1 interactors in maize cells. Collectively, our data identified three ubiquitin-proteasome pathway-related proteins (ZmSIP1, ZmSIP2, ZmSIP3) that either interact with or are close to UmSee1 during host infection of maize withU. maydis.ZmSIP3 represents a cell cycle regulator which degradation appears to be promoted in the presence of UmSee1. Our data provide a possible explanation for the requirement of UmSee1 in tumor formation duringU. maydis-Zea maysinteraction.