Mechanistic basis for the emergence of EPS1 as a catalyst in salicylic acid biosynthesis of Brassicaceae.

Publication Type:

Journal Article

Source:

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 Acid

Abstract:

<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&#39;s potential to enhance defense mechanisms in non-Brassicaceae plants lacking an EPS1 ortholog. Our findings illustrate the evolutionary adaptation of an ancestral enzyme&#39;s active site to enable a novel catalytic mechanism that boosts SA production in Brassicaceae plants.</p>

PDB: 
6WCS (AtEPS1 Apo), and 6WAO (AtEPS1+CAG)
Detector: 
EIGER
Beamline: 
24-ID-E