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Updated: May 26, 2026

Split Green Fluorescent Protein System to Visualize Effectors Delivered from Bacteria During Infection
Published on: May 24, 2018
A bacterial cysteine protease effector protein interferes with photosynthesis to suppress plant innate immune
José J Rodríguez-Herva1, Pablo González-Melendi, Raquel Cuartas-Lanza
1Centro de Biotecnología y Genómica de Plantas (CBGP). Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria., Parque Científico y Tecnológico de la UPM. Campus de Montegancedo. 28223 Pozuelo de Alarcón, Madrid, Spain.
Abstract:
The bacterial pathogen Pseudomonas syringae pv tomato DC3000 suppresses plant innate immunity with effector proteins injected by a type III secretion system (T3SS). The cysteine protease effector HopN1, which reduces the ability of DC3000 to elicit programmed cell death in non-host tobacco, was found to also suppress the production of defence-associated reactive oxygen species (ROS) and callose when delivered by Pseudomonas fluorescens heterologously expressing a P. syringae T3SS. Purified His(6) -tagged HopN1 was used to identify tomato PsbQ, a member of the oxygen evolving complex of photosystem II (PSII), as an interacting protein. HopN1 localized to chloroplasts and both degraded PsbQ and inhibited PSII activity in chloroplast preparations, whereas a HopN1(D299A) non-catalytic mutant lost these abilities. Gene silencing of NtPsbQ in tobacco compromised ROS production and programmed cell death by DC3000. Our data reveal PsbQ as a contributor to plant immunity responses and a target for pathogen suppression.
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