Aziridine Formation by a Fe II /α‐Ketoglutarate Dependent Oxygenase and 2‐Aminoisobutyrate Biosynthesis in Fungi

Aziridine is a characteristically reactive molecule with increased bioactivity due to its strained ring structure. Here, we investigated the biosynthesis of 2‐aminoisobutyric acid (AIB) in Penicillium , and successfully reconstituted the three‐step biosynthesis from L‐Val to AIB in vitro. This previously unknown aziridine formation pathway proceeded with the non‐heme iron and α‐ketoglutarate‐dependent (Fe II /αKG) oxygenase TqaL, followed by aziridine ring opening by the haloalkanoic acid dehalogenase (HAD)‐type hydrolase TqaF, and subsequent oxidative decarboxylation by the NovR/CloR‐like non‐heme iron oxygenase TqaM. Furthermore, the X‐ray crystal structure of the C−N bond forming Fe II /αKG oxygenase TqaL was solved at 2.0 Å resolution. This work presents the first molecular basis for aziridine biogenesis, thereby expanding the catalytic repertoire of the Fe II /αKG oxygenases. We also report the unique aziridine ring opening by a HAD‐type hydrolase and the remarkable oxidative decarboxylation by a non‐heme iron oxygenase to produce AIB.