No abstract

As a commercial antibiotic, bicyclomycin (BCM) is currently the only known natural product targeting the transcription termination factor rho. It belongs to a family of highly functionalized diketopiperazine (DKP) alkaloids and bears a unique O-bridged bicyclo[4.2.2]piperazinedione ring system, a C1 triol, and terminal exo-methylene groups. We have identified and characterized the BCM biosynthetic pathway by heterologous biotransformations, in vitro biochemical assays, and one-pot enzymatic synthesis. A tRNA-dependent cyclodipeptide synthase guides the heterodimerization of leucine and isoleucine to afford the DKP precursor; subsequently, six redox enzymes, including five α-ketoglutarate/Fe -dependent dioxygenases and one cytochrome P450 monooxygenase, regio- and stereoselectively install four hydroxy groups (primary, secondary, and two tertiary), an exo-methylene moiety, and a medium-sized bridged ring through the functionalization of eight unactivated C-H bonds.

As acommercial antibiotic,bicyclomycin (BCM) is currently the only knownn atural product targeting the transcription termination factor rho.Itbelongs to afamily of highly functionalizedd iketopiperazine (DKP) alkaloids and bears aunique O-bridged bicyclo[4.2.2]piperazinedione ring system, aC 1t riol, and terminal exo-methylene groups.W eh ave identified and characterized the BCM biosynthetic pathway by heterologous biotransformations,i nvitro biochemical assays, and one-pot enzymatic synthesis.AtRNA-dependent cyclodipeptide synthase guides the heterodimerization of leucine and isoleucine to affordthe DKP precursor;subsequently,six redox enzymes,i ncluding five a-ketoglutarate/Fe 2+ -dependent dioxygenases and one cytochrome P450 monooxygenase, regio-and stereoselectively install four hydroxy groups (primary,s econdary,a nd two tertiary), an exo-methylene moiety, and amedium-sized bridged ring through the functionalization of eight unactivated CÀHb onds.