Structural and functional insights into Jasmonate ZIM-domain 2 (GhJAZ2) interactions in cotton fiber development via Jasmonic acid signaling

Abstract

Cotton is one of the world's most vital fiber crops, and enhancing its fiber quality continues to be a major priority for the textile sector. The protein GhJAZ2, belonging to the Jasmonate ZIM-domain (JAZ) family, functions as a transcriptional repressor that influences fiber initiation by interacting with proteins such as GhMYB25-like, GhWD40, GhMYC2, GhGL1, and GhJI1, all of which participate in jasmonic acid (JA) signaling pathways. Despite their known involvement, detailed insights into their interactions and precise three-dimensional structures remain elusive.

In this research, we aimed to characterize the functional roles of GhJAZ2 and its interacting partners, and to model their structural interactions computationally. We utilized homology-based modeling to construct 3D models and applied HADDOCK software for protein-protein docking to accurately pinpoint interaction sites and assess binding affinities. Our findings indicated that the ZIM domain of GhJAZ2 serves as the central interaction region. Specifically, key residues within the TIFY motif, particularly ILE126 and TYR128, play a significant role in binding GhWD40, GhMYC2, GhGL1, and GhJI1 proteins. These results underscore the critical role of the TIFY motif in enabling GhJAZ2 to act as a repressor during fiber development.

This study provides valuable new insights into the molecular processes involved in JA-driven fiber development in cotton, identifying potential genetic targets that could be manipulated to significantly improve fiber quality.