Enzyme Complexes of Ptr4CL and PtrHCT Modulate Co-enzyme A Ligation of Hydroxycinnamic Acids for Monolignol Biosynthesis in Populus trichocarpa

• DOI: 10.3389/fpls.2021.727932
• Publication Date: 2021-10-07T13:56:19Z
• Authors: Chien-Yuan Lin; Yi Sun; Jina Song; Hsi-Chuan Chen; Rui Shi; Chenmin Yang; Jie Liu; Sermsawat Tunlaya...; Baoguang Liu; Philip L. Loziuk; Cranos M. Williams; David C. Muddiman; Ying-Chung Jimmy Lin; Ronald R. Sederoff; Jack P. Wang; Vincent L. Chiang
• Keywords: Monolignol; Populus trichocarpa; Hydroxycinnamic acid; Bimolecular fluorescence complementation; Phenylpropanoid

Co-enzyme A (CoA) ligation of hydroxycinnamic acids by 4-coumaric acid:CoA ligase (4CL) is a critical step in the biosynthesis monolignols. Perturbation 4CL activity significantly impacts lignin content diverse plant species. In Populus trichocarpa , two well-studied xylem-specific Ptr4CLs (Ptr4CL3 and Ptr4CL5) catalyze CoA acid to 4-coumaroyl-CoA caffeic caffeoyl-CoA. Subsequently, 4-hydroxycinnamoyl-CoA:shikimic hydroxycinnamoyl transferases (PtrHCT1 PtrHCT6) mediate conversion Here, we show that modulated Ptr4CL/PtrHCT protein complexes. Downregulation PtrHCTs reduced Ptr4CL activities stem-differentiating xylem (SDX) transgenic P. . The interactions were then validated vivo using biomolecular fluorescence complementation (BiFC) pull-down assays SDX extracts. Enzyme recombinant proteins PtrHCT showed elevated for when supplemented with PtrHCT. Numerical analyses based on an evolutionary computation estimated stoichiometry complex consist one PtrHCTs, which was experimentally confirmed chemical cross-linking extracts proteins. Based these results, propose complexes modulate metabolic flux monolignol during wood formation