Does the Phospho-state of AZI1’s Proline-Rich Region Affect Its Localization to Chloroplasts?
Session Number
Project ID: BIO 12
Advisor(s)
DeQuantarius J Speed; University of Chicago
Dr. Jean Greenberg; University of Chicago
Discipline
Biology
Start Date
22-4-2020 9:10 AM
End Date
22-4-2020 9:25 AM
Abstract
Recognition of microbes or microbial products by plant receptors induces signaling cascades that prime broad-spectrum defense responses to suppress subsequent infections. In the primed state, plants are prepared to activate stronger defense responses more quickly than unprimed plants when challenged by pathogens and other stresses. An essential component of systemic priming is the protein AZI1, a member of the lipid transfer protein superfamily. Like AZI1, the regulatory kinase MPK3 is essential for priming. During infection, AZI1 accumulates in chloroplast outer envelope membranes via a mechanism that depends on MPK3, which suggests AZI1’s localization to chloroplasts is essential for priming defense responses. AZI1’s chloroplast association requires a novel bipartite targeting signal that consists of an N-terminal hydrophobic region and an internal proline-rich region (PRR). To better understand the molecular basis of priming, I am making unphosphorylatable and phosphomimetic mutations within the PRR of AZI1. Using Arabidopsis thaliana and Nicotiana benthamiana, I will assess how these mutations affect AZI1’s subcellular localization with an emphasis on localization to the chloroplasts.
Does the Phospho-state of AZI1’s Proline-Rich Region Affect Its Localization to Chloroplasts?
Recognition of microbes or microbial products by plant receptors induces signaling cascades that prime broad-spectrum defense responses to suppress subsequent infections. In the primed state, plants are prepared to activate stronger defense responses more quickly than unprimed plants when challenged by pathogens and other stresses. An essential component of systemic priming is the protein AZI1, a member of the lipid transfer protein superfamily. Like AZI1, the regulatory kinase MPK3 is essential for priming. During infection, AZI1 accumulates in chloroplast outer envelope membranes via a mechanism that depends on MPK3, which suggests AZI1’s localization to chloroplasts is essential for priming defense responses. AZI1’s chloroplast association requires a novel bipartite targeting signal that consists of an N-terminal hydrophobic region and an internal proline-rich region (PRR). To better understand the molecular basis of priming, I am making unphosphorylatable and phosphomimetic mutations within the PRR of AZI1. Using Arabidopsis thaliana and Nicotiana benthamiana, I will assess how these mutations affect AZI1’s subcellular localization with an emphasis on localization to the chloroplasts.