9WTS

Structure of the EpHTT from Echinacea purpurea

Summary for 9WTS

• Entry DOI: 10.2210/pdb9wts/pdb
• Descriptor: Hydroxycinnamoyl-CoA: tartaric acid hydroxycinnamoyl transferase, GLYCEROL (3 entities in total)
• Functional Keywords: hydroxycinnamoyl-coa:tartaric acid hydroxycinnamoyl transferase, transferase
• Biological source: Echinacea purpurea
• Total number of polymer chains: 2
• Total formula weight: 96616.63

Authors

Tang, D.,Bao, H.,Jiang, D.,Huang, X.F. (deposition date: 2025-09-16, release date: 2025-10-29, Last modification date: 2026-01-07)

Primary citation

Bao, H.,Jiang, D.,Tang, C.,Yin, Z.,Huang, X.,Fu, R.,Zhang, Y.,Li, Z.,Qi, S.,Cai, H.,Tang, D.
The crystal structure of EpHTT, a hydroxycinnamoyl transferase from Echinacea purpurea.
Acta Crystallogr D Struct Biol, 82:43-52, 2026

PubMed Abstract: Echinacea purpurea hydroxycinnamoyl-CoA:tartaric acid hydroxycinnamoyl transferase (EpHTT) is a cytosolic BAHD acyltransferase that catalyzes the transfer of caffeoyl groups to tartaric acid, a key step in chicoric acid biosynthesis. Understanding the structure of EpHTT is essential to elucidate the molecular basis of substrate recognition and catalytic specificity. Here, we report the crystal structure of apo-form EpHTT at 2.38 Å resolution, revealing a compact, globular architecture typical of the BAHD superfamily. The enzyme adopts a two-domain fold with conserved HXXXD and DFGWG motifs, forming a V-shaped catalytic cleft characteristic of BAHD acyltransferases. Structural comparison with homologous hydroxycinnamoyl transferase enzymes shows high conservation of the overall fold, while EpHTT exhibits unique adaptations that confer specificity for tartaric acid. These results provide a molecular framework for understanding the function and substrate specificity of HTT, offering insights for the metabolic engineering of chicoric acid production.

PubMed: 41328548
DOI: 10.1107/S205979832501023X

Experimental method

X-RAY DIFFRACTION (2.29 Å)