Characterization of molecular mechanisms regulating RPM1 protein function and localization

• Applicant: Dr. Farid El Kasmi
• Subject Area: Plant Cell and Developmental Biology
• Term: from 2013 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 234728771

Unlike animals plants are restricted to an innate immune system. So far we know relatively little about the basic molecular mechanisms leading to resistance. The long-term goal of the proposed project is to understand the mechanisms by which the intracellular innate immune receptors are activated and how they function, once active, to initiate successful disease resistance responses. The project will focus on an intracellular immune receptor of the NLR protein superfamily. NLRs are the key proteins for pathogen detection in the innate immune systems of both plants and animals. NLRs were originally discovered in plants where they are the basis for disease resistance. Not until later, NLRs were discovered in animals, where they play a major role in regulating innate immune signaling in infectious and autoimmune diseases. Once activated, NLRs induce a complex output response that ultimately leads to the restriction of pathogen growth. Despite the key role of NLRs in innate immunity in plants and animals, there is to date no generalizable model describing how NLRs transition from an inactive resting state to an active signaling state after recognition of microbial signals. Recent work on various NLR proteins demonstrates that not all NLRs are activated in, or function in, the same manner what suggests mechanistic differences. I intend to use biochemical and cell-biological techniques to dissect the molecular mechanism regulating the activation, confirmation and localization of the plant NLR protein RPM1. I will use both transient assays in N. benthamiana and detailed follow up transgenic Arabidopsis at native expression levels to understand the dedicated function of the distinct RPM1 domains in the initiation of a robust immune response. Additionally, I plan to identify new interactors of activated RPM1 using an elegant approach where I can freeze RPM1-associated proteins. Further, I will finish a genetic screen to isolate genes that are important for the regulation of active RPM1.Plant NLR receptors are used by essentially all land plants to sense and respond to pathogen attack. Similarly, the animal NLR receptors respond to microbial signals in hosts as diverse as sea urchins and humans. Therefore a mechanistic understanding of NLR function is not only a prerequisite for rational deployment of the plant immune system in crops but also for the development of treatments for various human diseases. Thus, it is vital to understand how signal competent receptors are organized before infection, the precise mechanisms by which they are activated, and how this activation is translated in an appropriate output response.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. Jeffrey Dangl