8HBT

AmAT7-3 mutant A310G

Summary for 8HBT

• Entry DOI: 10.2210/pdb8hbt/pdb
• Descriptor: AmAT7-3-A310G, Astragaloside IV (3 entities in total)
• Functional Keywords: acetyltransferase, triterpene saponin, mutant, biosynthetic protein
• Biological source: Astragalus membranaceus
• Total number of polymer chains: 1
• Total formula weight: 50759.44

Authors

Wang, L.L. (deposition date: 2022-10-31, release date: 2023-09-13, Last modification date: 2024-02-14)

Primary citation

Wang, L.,Jiang, Z.,Zhang, J.,Chen, K.,Zhang, M.,Wang, Z.,Wang, B.,Ye, M.,Qiao, X.
Characterization and structure-based protein engineering of a regiospecific saponin acetyltransferase from Astragalus membranaceus.
Nat Commun, 14:5969-5969, 2023

PubMed Abstract: Acetylation contributes to the bioactivity of numerous medicinally important natural products. However, little is known about the acetylation on sugar moieties. Here we report a saponin acetyltransferase from Astragalus membranaceus. AmAT7-3 is discovered through a stepwise gene mining approach and characterized as the xylose C3'/C4'-O-acetyltransferse of astragaloside IV (1). To elucidate its catalytic mechanism, complex crystal structures of AmAT7-3/1 and AmAT7-3/1 are obtained, which reveal a large active pocket decided by a specific sequence AADAG. Combining with QM/MM computation, the regiospecificity of AmAT7-3 is determined by sugar positioning modulated by surrounding amino acids including #A310 and #L290. Furthermore, a small mutant library is built using semi-rational design, where variants A310G and A310W are found to catalyze specific C3'-O and C4'-O acetylation, respectively. AmAT7-3 and its variants are also employed to acetylate other bioactive saponins. This work expands the understanding of saponin acetyltransferases, and provide efficient catalytic tools for saponin acetylation.

PubMed: 37749089
DOI: 10.1038/s41467-023-41599-7

Experimental method

X-RAY DIFFRACTION (1.96 Å)