β-Methyltryptamine Provoking the Crucial Role of Strictosidine Synthase Tyr151-OH for Its Stereoselective Pictet-Spengler Reactions to Tryptoline-type Alkaloids

Haicheng Liu, Santosh Panjikar, Xiang Sheng, Yushi Futamura, Chenghua Zhang, Nana Shao, Hiroyuki Osada, Hongbin Zou

Research output: Contribution to journalArticleResearchpeer-review

3 Citations (Scopus)

Abstract

Strictosidine synthase (STR), the gate enzyme for monoterpenoid indole alkaloid biosynthesis, catalyzes the Pictet-Spengler reaction (PSR) of various tryptamine derivatives with secologanin assisted by "indole sandwich"stabilization. Continuous exploration with β-methyltryptamine (IPA) stereoselectively delivered the C6-methylstrictosidines and C6-methylvincosides by enzymatic and nonenzymatic PSR, respectively. Unexpectedly, the first "nonindole sandwich"binding mode was witnessed by the X-ray structures of STR1-ligand complexes. Site-directed mutagenesis revealed the critical cryptic role of the hydroxyl group of Tyr151 in IPA biotransformation. Further computational calculations demonstrated the adjustable IPA position in STR1 upon the binding of secologanin, and Tyr151-OH facilitates the productive PSR binding mode via an advantageous hydrogen-bond network. Further chemo-enzymatic manipulation of C6-methylvincosides successfully resulted in the discovered antimalarial framework (IC50 = 0.92 μM).

Original languageEnglish
Pages (from-to)187-197
Number of pages11
JournalACS Chemical Biology
Volume17
Issue number1
DOIs
Publication statusPublished - 21 Jan 2022

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