Characterization of Enzymes Catalyzing the Initial Steps of the β-Lactam Tabtoxin Biosynthesis

Tabtoxin is a beta-lactam ring-containing phytotoxin produced by a plant pathogenic Pseudomonas species. Here, we describe the early stages of tabtoxin biosynthesis, involving a C-methylation reaction catalyzed by the S-adenosyl-L-methionine-dependent methyltransferase TblA as the initial step for the beta-lactam construction. Gene deletion and in vitro biochemical assays demonstrated that the Gcn5-related N-acetyltransferase domain of TblD catalyzes the acetylation of the alpha-amino group of 5-methyl-L-lysine. This establishment of the early reaction steps lays the foundation for characterizing unique beta-lactam biosynthesis.

Automated summary

This study describes the early stages of Tabtoxin biosynthesis and identifies the roles of TblA and TblD in the process through gene deletion and in vitro biochemical assays, providing insights into the progression of these reactions.