A critical role of two positively charged amino acids in the Jas motif of Arabidopsis JAZ proteins in mediating coronatine- and jasmonoyl isoleucine-dependent interactions with the COI1 F-box protein

Authors

Maeli Melotto, Michigan State University
Christy Mecey, Michigan State University
Yajie Niu, Washington State University, Pullman, WA
Hoo Sun Chung, Michigan State University
Leron Katsir, Michigan State University
Jian Yao, Michigan State University
Weiqing Zeng, Michigan State University
Bryan Thines, Washington State University, Pullman, WA
Paul E. Staswick, University of Nebraska-LincolnFollow
John Browse, Washington State University, Pullman, WA
Gregg A. Howe, Michigan State University
Sheng Yang He, Michigan State University

Date of this Version

July 2008

Comments

Published in The Plant Journal (2008).

Abstract

Coronatine is an important virulence factor produced by several pathovars of the bacterial pathogen Pseudomonas syringae. The structure of coronatine is similar to that of a class of plant hormones called jasmonates (JAs). An important step in JA signaling is the SCF^COI1 E3 ubiquitin ligase-dependent degradation of JAZ repressor proteins. We have recently shown that jasmonoyl isoleucine (JA-Ile) promotes physical interaction between Arabidopsis JAZ1 and COI1 (the F-box component of SCF^COI1) proteins, and that the JAIle- dependent COI1–JAZ1 interaction could be reconstituted in yeast cells (i.e. in the absence of other plant proteins). Here we show that coronatine, but not its two biosynthetic precursors, also promotes interaction between Arabidopsis COI1 and multiple JAZ proteins. The C-terminal Jas motif, but not the N-terminal (NT) domain or central ZIM domain of JAZ proteins, is critical for JA-Ile/coronatine-dependent interaction with COI1. Two positively charged amino acid residues in the Jas domain were identified as essential for coronatinedependent COI1–JAZ interactions. Mutations of these two residues did not affect the ability of JAZ1 and JAZ9 to interact with the transcription factor AtMYC2. Importantly, transgenic Arabidopsis plants expressing JAZ1 carrying these two mutations exhibited JA-insensitive phenotypes, including male sterility and enhanced resistance to P. syringae infection. These results not only suggest that coronatine and JA-Ile target the physical interaction between COI1 and the Jas domain of JAZ repressors, but also illustrate the critical role of positively charged amino acids in the Jas domain in mediating the JA-Ile/coronatine-dependent JAZ interaction with COI1.