Wrestling with pathogens: host SUMOylation and bacterial interference in the plant immune system

University Of Missouri-Columbia, Columbia MO

Investigators

Abstract

A fundamental "engineering" problem in signal processing consists of integrating trigger threshold and dynamic range into a beneficial balance between sensitivity and specificity. A good example is the immune system, which organisms need to carefully control so that it can be rapidly activated when faced with a threatening pathogen, but kept in check to prevent damaging side effects. In plants, one of the strongest immune responses is triggered when intracellular immune receptors detect the presence of intruding pathogen proteins deployed by the pathogen to manipulate the host cell, a process called effector-triggered immunity. This project aims to uncover principles by which living organisms calibrate the complex signaling modules that regulate the specificity and intensity of immune responses. On a practical level, detailed knowledge of the plant immune response may lead to crop plants with improved durability of innate pathogen resistance in the long term, with significant benefits to sustainable agricultural and biomass production and the environment. This project's broader impacts also include the training of undergraduate and graduate students and of a post-doctoral researcher. In addition, the project will support students in a campus-wide program called Freshman Research in Plant Sciences (FRIPS), and will further develop connections to middle and high school teachers in Sedalia, MO, through classroom visits and the organization of research modules at MU for teachers in the summer. The focus is on an immune regulator in the plant Arabidopsis thaliana called SRFR1. Current understanding of SRFR1 protein function suggests that SRFR1 is an immune adaptor protein that temporally and spatially regulates the presence and stability of protein complexes to fine-tune immune outputs. In this project, the mechanisms that regulate SRFR1 protein-protein interactions will be investigated. Specifically, the indication that SRFR1 binds SUMO, a small protein that is attached to other proteins to regulate their location in the cell, suggests a mechanism for regulating SRFR1 interactions with other proteins by SUMOylation. This will be tested using a combination of genetics, cell biology and proteomics to establish whether and when SUMOylation of SRFR1 client proteins occurs, and whether this determines the cellular location of protein complexes. In addition, the project will investigate if pathogens interfere with this process.