N-Glycosylation mediation of Plant Immunity in Arabidopsis Matt Borchardt and Jessica Allen

Max-Planck Society for the Advancement of Science Originally created as the Kaiser Wilhelm Society in 1911, changed in 1948 Boasts 32 Nobel Prizes awarded to their scientists Top Non-University Institution in Science by Times Higher Education Albert Einstein, Fritz Haber, and Peter Debye were named directors at some point in its history http://en.wikipedia.org/wiki/Max-Planck-Gesellschaft

Arabidopsis Brassicaceae family model organism ABC Plant Model First plant to have entire genome sequenced http://en.wikipedia.org/wiki/Arabidopsis

Signaling in Cells Cells are constantly being introduced to various signals inside and outside of the cell Signal receptors are signal-specific Causes a cellular response

Example of Cell Signaling 219.221.200.61/ywwy/zbsw(E)/edetail6.htm

Cell Signaling and Plants Cell signaling is important for Plant Immunity Provides feedback systems to promote cellular defense Growth inhibition Production of Reactive Oxygen Species (ROS) “oxidative burst” Apoptosis

Plant Receptors Pattern Recognition Receptors (PRRs) membrane-bound protein of the innate immune system recognize microbe-associated molecular patterns (MAMPs) on pathogens Contain membrane-bound polysaccharides

Arabidopsis has approximately 56 known RLPs EFR recognizes and responds to elf18 FLS2 recognizes and responds to flg22 MAMPs are recognized by N-glycans on PRRs

N-Glycans Attach to asparagine residues of plasma membrane Initial contact between plant cells and pathogens

N-glycosylation Occurs in eukaryotes during/after translation Linking of 14-sugar precursor to the asparagine in the polypeptide chain 12-52.Molecular Biology of the Cell, 4th Edition

Oligosaccharyltransferase Complex Transfers the 14-sugar oligosaccharide from dolichol to the protein The central step in N-linked glycosylation Located in the ER Post-translational modification http://www.ier.tokushima-u.ac.jp/bunshi-seiri/physiol/images/PfSTT3.jpg

N-Glycosylation Intermediates

Altered/Prevention of N-Glycosylation Creates unfolding of proteins Only correctly folded proteins are exported from the ER Causes a reduction in receptor accumulation Causes lack of receptor-signal induced pathways Leads to decreased immune response

In this study Mutated genes produce plants with modifications in the N-glycosylation steps stt3a Genes present in ER which encode for oligosaccharyltransferase complex

Tunicamycin Antibiotic Blocks glycoprotein synthesis in first step of glycosylation Causes arrest of cell cycle in G1 Produced by bacterium Streptomyces http://fermentek.co.il/tunicamycin.htm

Endoplasmic Reticulum Bacteria MAMP Bacteria MAMP PRR-EFR PRR-FLS2 Plasma Membrane Endoplasmic Reticulum Golgi Apparatus Seedling Growth ROS