Molecular basis of enzymaticnitrogen-nitrogen formation by a family of zinc-binding cupin enzymes

 Abstract

Molecules with anitrogen-nitrogen (N-N) bond in their structures exhibit various biologicalactivities and other unique properties. A few microbial proteins are recentlyemerging as dedicated N-N bond forming enzymes in natural product biosynthesis.However, the details of these biochemical processes remain largely unknown.Here, through in vitro biochemical characterization and computational studies,we report the molecular basis of hydrazine bond formation by a family ofdi-domain enzymes. These enzymes are widespread in bacteria and sometimesnaturally exist as two standalone enzymes. We reveal that the methionyl-tRNAsynthase-like domain/protein catalyzes ATP-dependent condensation of two aminoacids substrates to form a highly unstable ester intermediate, which issubsequently captured by the zinc-binding cupin domain/protein and undergoesredox-neutral intramolecular rearrangement to give the N-N bond containingproduct. These results provide important mechanistic insights into enzymaticN-N bond formation and should facilitate future development of novel N-Nforming biocatalyst. Enzymes involved in the synthesis of nitrogen-nitrogenbond containing molecules have been identified but the processes remain largelyunknown. Here, the authors use biochemical characterisation and computermodelling to study the molecular basis of hydrazine bond formation by a familyof di-domain enzymes.