PBS3 and EPS1 Complete Salicylic Acid Biosynthesis from Isochorismate in Arabidopsis

作     者：Michael P.Torrens-Spence Anastassia Bobokalonova Valentina Carballo Christopher MGlinkerman Toma(s)Pluskal Amber Shen Jing-Ke Weng 

作者机构：Whitehead Institute for Biomedical Research455 Main StreetCambridgeMA 02142USA Department of BiologyMassachusetts Institute of TechnologyCambridgeMA 02139USA 

出 版 物：《Molecular Plant》 (分子植物（英文版）)

年 卷 期：2019年第12卷第12期

页      面：1577-1586页

核心收录：

学科分类：0710[理学-生物学] 081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070305[理学-高分子化学与物理] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0901[农学-作物学] 0703[理学-化学] 0902[农学-园艺学] 

基　　金：This work was supported by the Pew Scholar Program in the Biomedical Sciences the Searle Scholars Program and the National Science Foundation(CHE-1709616) 

主　　题：salicylic acid PBS1 EPS1 isochorismic acid plant defense plant hormone 

摘      要：Salicylic acid(SA)is an important phytohormone mediating both local and systemic defense responses in *** over half a century of research,how plants biosynthesize SA remains *** Arabidop-sis,a major part of SA is derived from isochorismate,a key intermediate produced by the isochorismate syn-thase,which is reminiscent of SA biosynthesis in *** bacteria employ an isochorismate pyru-vate lyase(IPL)that catalyzes the turnover of isochorismate to pyruvate and SA,plants do not contain an IPL ortholog and generate SA from isochorismate through an unknown *** genetic and biochemical approaches,we delineated the SA biosynthetic pathway downstream of isochorismate in *** found that PBS3,a GH3 acyl adenylase-family enzyme important for SA accumulation,catalyzes ATP-and Mg2+-dependent conjugation of L-glutamate primarily to the 8-carboxyl of isochorismate and yields the key SA biosynthetic intermediate,isochorismoyl-glutamate ***,we discovered that EPS1,a BAHD acyltransferase-family protein with a previously implicated role in SA accumulation upon pathogen attack,harbors a noncanonical active site and an unprecedented isochorismoyl-glutamate A pyruvoyl-glutamate lyase activity that produces SA from the isochorismoyl-glutamate A ***,PBS3 and EPS1 form a two-step metabolic pathway to produce SA from isochorismate in Arabidopsis,which is distinct from how SA is biosynthesized in *** study closes a major knowledge gap in plant SA meta-bolism and would help develop new strategies for engineering disease resistance in crop plants.