Assembly of JAZ–JAZ and JAZ–NINJA complexes in jasmonate signaling

Abstract

Jasmonates (JAs) are plant hormones with crucial roles in development and stress37 resilience. They activate MYC transcription factors by mediating the proteolysis of MYC38 inhibitors called JAZ. In the absence of JA, JAZ proteins bind and inhibit MYC through39 the assembly of MYC–JAZ–NINJA–TPL repressor complexes. However, JAZ and NINJA40 are predicted to be largely intrinsically unstructured, which precluded their experimental41 structure determination. Through a combination of biochemical, mutational, and42 biophysical analyses and AlphaFold-derived ColabFold modeling, we characterized JAZ–43 JAZ and JAZ–NINJA interactions and generated models with detailed, high confidence44 domain interfaces. We demonstrate that JAZ, NINJA, and MYC interface domains are45 dynamic in isolation and become stabilized in a stepwise order upon complex assembly. In46 contrast, most JAZ and NINJA regions outside of the interfaces remain highly dynamic47 and cannot be modeled in a single conformation. Our data indicate that the small JAZ ZIM48 motif mediates JAZ–JAZ and JAZ–NINJA interactions through separate surfaces, and49 further suggest that NINJA modulates JAZ dimerization. This study advances knowledge50 of JA signaling by providing insight into dynamics, interactions, and structure of the JAZ–51 NINJA core of the JA repressor complex.