A radical carboxyl migration

Biochemistry The antibiotic nosiheptide, produced by Streptomyces actuosus , has high activity against multidrug-resistant pathogens. The enzymes involved in its biosynthesis include NosL, which cannibalizes tryptophan and forms a methylindolic acid precursor. Although NosL is included in a growing family of remarkable radical SAM enzymes, the mechanism by which it functions has been difficult to identify. Using spectroscopic and theoretical approaches, Sicoli et al. show that an unexpected radical intermediate forms during the course of the reaction (see the Perspective by Bridwell-Rabb and Drennan). Unlike similar known enzymes, NosL cleaves a Cα-C bond, which results in the migration of tryptophan's carboxyl group to its side-chain indole. Science , this issue p. [1320][1]; see also p. [1266][2] [1]: /lookup/doi/10.1126/science.aad8995 [2]: /lookup/doi/10.1126/science.aaf4942