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

Torrens-Spence, M. P.; Li, T.; Wang, Z.; Glinkerman, C. M.; Matos, J. O.; Wang, Y.; Weng, J.-K.

doi:10.1101/2021.08.21.457228

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bioRxiv · 10.1101/2021.08.21.457228

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

Torrens-Spence, M. P.·Li, T.·Wang, Z.·Glinkerman, C. M.·Matos, J. O.·Wang, Y.·Weng, J.-K.

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Abstract

Unique to plants in the Brassicaceae family, the production of the plant defense hormone salicylic acid (SA) from isochorismate is accelerated by an evolutionarily young isochorismoyl-glutamate pyruvoyl-glutamate lyase, EPS1, which belongs to the BAHD acyltransferase protein family. Here, we report the crystal structures of apo and substrate-analog-bound EPS1 from Arabidopsis thaliana. Assisted by microsecond molecular dynamics simulations, we uncover a unique pericyclic rearrangement lyase mechanism facilitated by the active site of EPS1. We reconstitute the isochorismate-derived pathway of SA biosynthesis in Saccharomyces cerevisiae, which serves as an in vivo platform that helps identify active-site residues critical for EPS1 activity. This study describes the birth of a new catalyst in plant phytohormone biosynthesis by reconfiguring the ancestral active site of a progenitor enzyme to catalyze alternative reaction. One sentence summaryBy reconfiguring the active site of a progenitor acyltransferase-fold, EPS1 acquired the unique, evolutionarily new lyase activity that accelerates phytohormone salicylic acid production in Brassicaceae plants.

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Torrens-Spence, M. P., Li, T., Wang, Z., Glinkerman, C. M., Matos, J. O., Wang, Y., Weng, J.-K.. 2021-08-22. Mechanistic basis for the emergence of EPS1 as a catalyst in plant salicylic acid biosynthesis. https://doi.org/10.1101/2021.08.21.457228

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