Isonitrile biosynthesis by non-heme iron(II)-dependent oxidases/decarboxylases

The isonitrile group is a compact, electron-rich moiety coveted for its commonplace as a building block and bioorthogonal functionality in synthetic chemistry and chemical biology. Hundreds of natural products containing an isonitrile group with intriguing bioactive properties have been isolated from diverse organisms. Our recent discovery of a conserved biosynthetic gene cluster in some Actinobacteria species highlighted a novel enzymatic pathway to isonitrile formation involving a non-heme iron(II) and α-ketoglutarate-dependent dioxygenase. Here, we focus this chapter on recent advances in understanding and probing the biosynthetic machinery for isonitrile synthesis by non-heme iron(II) and α-ketoglutarate-dependent dioxygenases. We will begin by describing how to harness isonitrile enzymatic machinery through heterologous expression, purification, synthetic strategies, and in vitro biochemical/kinetic characterization. We will then describe a generalizable strategy to probe the mechanism for isonitrile formation by combining various spectroscopic methods. The chapter will also cover strategies to study other enzyme homologs by implementing coupled assays using biosynthetic pathway enzymes. We will conclude this chapter by addressing current challenges and future directions in understanding and engineering isonitrile synthesis.