Deciphering the O-Carbamoylation Modification Mechanism in Venturicidin A Biosynthesis.

Herein, VtdB was identified as an essential O-carbamoyltransferase that catalyzes the conversion of venturicidin B (3) to venturicidin A (1). Notably, a 2.8 Å resolution crystal structure of the VtdB-substrate complex (VtdB/VTD-B) revealed that 3 occupies a specific hydrophobic pocket within the Kael-like domain, where His35 plays a critical deprotonation role during enzymatic catalysis. These biochemical and structural research provides the first mechanistic insight into d-olivose-glycosylated macrolide recognition by the carbamoyltransferase, enabling its future engineering.