[대학원 생명과학과 세미나 안내]
연사 : 정의환 교수 (고려대학교 생명공학과)
연제 : Differential host protein modifications by bacterial effector proteins and plant immunity
일시 : 2020년 11월 6일 (금) 오후 5시
장소 : 온라인 화상 강의로 진행됩니다.
초청교수 : 최해웅 교수
Abstract
Plants employ a family of intracellular receptors called Nucleotide-binding leucine-rich repeat (NLR) proteins to defend themselves against disease. Most NLRs function by monitoring the modification of other plant proteins targeted by secreted pathogen proteins. When an NLR protein recognizes the change of these target proteins, the plant mounts immune responses. In Arabidopsis, the NLR protein RPM1 can detect the presence of two completely different bacterial proteins, AvrB and AvrRpm1. Both bacterial proteins target the same plant protein, RIN4. While it has been known that AvrB and AvrRpm1 target RIN4 since 2002, what they do to RIN4 has remained unclear.
Large amounts of modified RIN4 protein were able to be purified by heterologous expression in Nicotiana behtmiana, followed by mass spectrometry analysis. AvrRpm1 catalyzes the addition of ADP-ribose on two specific amino acids of RIN4, both of which reside within so-called ‘nitrate-induced (NOI) domains’. RIN4 contains two NOI domains, and prior work had shown that phosphorylation of threonine 166 within the C-terminal NOI domain of Arabidopsis RIN4 can activate RPM1 NLR protein. This study revealed that the addition of ADP-ribose on aspartate 153 (D153) promotes phosphorylation on T166, thus explaining how AvrRpm1 activates RPM1. Additionally, it was revealed that the C-terminal NOI domain mediates the association of RIN4 with EXO70 protein family, proteins involved in secretion. In the absence of RPM1, we speculate that ADP-ribosylation of RIN4 enhances its association with EXO70 to inhibit secretion of defense compounds.