RXLR Effector-Plant Protein Interaction Network

Oomycete plant pathogens deliver RXLR effectors inside plant cells to alter host processes to their advantage. Effectors interact with plant proteins including their cognate targets and helpers to achieve their functions. This study aims to identify the plant proteins interacting with RXLR effectors and ultimately the function of the effectors in planta. We transiently expressed 66 FLAG-tagged Phytophthora infestans RXLR effectors in Nicotiana benthamiana using the high-expression vector pTRBO. Effector fusions and associated host proteins were co-immunoprecipitated (coIP) and identified by LC-MS/MS spectrum matching against N. benthamiana proteome database. Out of 66 effectors, 59 were expressed to sufficient levels for co-IP and identification by mass spectrometry. GO annotation of associated plant proteins revealed 35 plant processes that might be targeted by the effectors. We classified the candidate interacters with a scoring system. So far, we confirmed more than 20 effector-plant protein associations. Notably, we found that the PexRD12/31 effectors associated and co-localized with components of vesicle trafficking machinery including VAMPs, VAC14, coatomers, vesicle fusing ATPase, syntaxin, exocyst, and Ras-related proteins. PexRD31 increased the number of FYVE-labelled endosomal membrane compartments in plant cells, suggesting that the effector modulates a process related to endosomal trafficking.