A Cysteine-Reloading Process Initiating the Biosynthesis of the Bicyclic Scaffold of Dithiolopyrrolones

Dithiolopyrrolone antibiotics are well known for their outstanding biological activities, and their biosynthesis has been studied vigorously. However, the biosynthesis mechanism of the characteristic bicyclic scaffold is still unknown after years of research. To uncover this mechanism, a multi-domain non-ribosomal peptide synthase DtpB from the biosynthetic gene cluster of thiolutin was selected as an object to study. We discovered that its adenylation domain not only recognized and adenylated cysteine, but also played an essential role in the formation of the peptide bond. Notably, an eight-membered ring compound was also discovered as an intermediate during the formation of the bicyclic structure. Based on these findings, we propose a new mechanism for the biosynthesis of the bicyclic scaffold of dithiolopyrrolones, and unveil additional functions of the adenylation domain.

Automated summary

Dithiolopyrrolone antibiotics have well-known biological activities, but the biosynthesis mechanism of the characteristic bicyclic scaffold is still unknown. In this study, the adenylation domain of a multi-domain non-ribosomal peptide synthase DtpB from the biosynthetic gene cluster of thiolutin was found to not only recognize and adenylate cysteine, but also play a crucial role in peptide bond formation. Additionally, an eight-membered ring compound was discovered as an intermediate during the formation of the bicyclic structure. These findings propose a new biosynthesis mechanism for the bicyclic scaffold of dithiolopyrrolones and reveal additional functions of the adenylation domain.