Structural basis for prereceptor modulation of plant hormones by GH3 proteins.
Westfall, C.S., Zubieta, C., Herrmann, J., Kapp, U., Nanao, M.H., Jez, J.M.(2012) Science 336: 1708-1711
- PubMed: 22628555 
- DOI: https://doi.org/10.1126/science.1221863
- Primary Citation of Related Structures:  
4EPL, 4EPM, 4EQ4, 4EQL, 4EWV - PubMed Abstract: 
Acyl acid amido synthetases of the GH3 family act as critical prereceptor modulators of plant hormone action; however, the molecular basis for their hormone selectivity is unclear. Here, we report the crystal structures of benzoate-specific Arabidopsis thaliana AtGH3.12/PBS3 and jasmonic acid-specific AtGH3.11/JAR1. These structures, combined with biochemical analysis, define features for the conjugation of amino acids to diverse acyl acid substrates and highlight the importance of conformational changes in the carboxyl-terminal domain for catalysis. We also identify residues forming the acyl acid binding site across the GH3 family and residues critical for amino acid recognition. Our results demonstrate how a highly adaptable three-dimensional scaffold is used for the evolution of promiscuous activity across an enzyme family for modulation of plant signaling molecules.
Organizational Affiliation: 
Department of Biology, Washington University, St. Louis, MO 63130, USA.