Structural basis of the Pseudomonas syringae effector HopBB1 targeting two Arabidopsis jasmonate repressors to activate the jasmonate-signaling pathway
L. WAN (1), L. Yang (1), P. Teixeira (1), F. Monteiro (1), J. Dangl (1) (1) University of North Carolina at Chapel Hill, U.S.A.

During infection, pathogens secret virulence effector proteins into plant cells to interfere with plant immunity through modifying or physically interacting with the host immunity components. Pathogen effectors in three life kingdoms (eubacteria, stramenopiles and fungi) have been shown to convergently target a host transcription factor TCP14 in Arabidopsis. Our lab recently found that TCP14 functions as a repressor in the plant phytohormone jasmonate (JA) signaling pathway. The Pseudomonas syringae effector HopBB1 targets at least two of the JA repressors, TCP14 and JAZ3, to activate the JA pathway and achieve its virulence function. Interaction with HopBB1 alleviates the repression of JAZ3 on MYC2, a transcriptional activator of the JA pathway. In addition, HopBB1 recruits TCP14 to the SCFCOI1-dependent JAZ3 degradation pathway by physically connecting the two JA repressors. The structural basis of how HopBB1 interacts TCP14 and JAZ3 remains to be defined. Recombinant proteins of HopBB1, JAZ3, MYC2 and TCP14 have been obtained from Escherichia coli expression systems. Biochemical essays demonstrated that these proteins interact in vitro and form complexes. Crystallization trials are currently underway to determine the structures of the complexes to help us understand the molecular basis of how HopBB1 disrupts the JAZ3-MYC2 interaction and connects TCP14 to JAZ3.

Abstract Number: P17-634
Session Type: Poster