Mechanistic basis for the emergence of EPS1 as a catalyst in salicylic acid biosynthesis of Brassicaceae.
Publication Type:
Journal ArticleSource:
Nat Commun, Volume 15, Issue 1, p.10356 (2024)Keywords:
Acyltransferases, Arabidopsis, Arabidopsis Proteins, Brassicaceae, Catalysis, Catalytic Domain, Crystallography, X-Ray, Glycine max, Molecular Dynamics Simulation, Plants, Genetically Modified, Saccharomyces cerevisiae, Salicylic AcidAbstract:
<p>Salicylic acid (SA) production in Brassicaceae plants is uniquely accelerated from isochorismate by EPS1, a newly identified enzyme in the BAHD acyltransferase family. We present crystal structures of EPS1 from Arabidopsis thaliana in both its apo and substrate-analog-bound forms. Integrating microsecond-scale molecular dynamics simulations with quantum mechanical cluster modeling, we propose a pericyclic rearrangement lyase mechanism for EPS1. We further reconstitute the isochorismate-derived SA biosynthesis pathway in Saccharomyces cerevisiae, establishing an in vivo platform to examine the impact of active-site residues on EPS1 functionality. Moreover, stable transgenic expression of EPS1 in soybean increases basal SA levels, highlighting the enzyme's potential to enhance defense mechanisms in non-Brassicaceae plants lacking an EPS1 ortholog. Our findings illustrate the evolutionary adaptation of an ancestral enzyme's active site to enable a novel catalytic mechanism that boosts SA production in Brassicaceae plants.</p>