Thiazoline-Specific Amidohydrolase PurAH Is the Gatekeeper of Bottromycin Biosynthesis.
Sikandar, A., Franz, L., Melse, O., Antes, I., Koehnke, J.(2019) J Am Chem Soc 141: 9748-9752
- PubMed: 31192589 
- DOI: https://doi.org/10.1021/jacs.8b12231
- Primary Citation of Related Structures:  
6I5S - PubMed Abstract: 
The ribosomally synthesized and post-translationally modified peptide (RiPP) bottromycin A2 possesses potent antimicrobial activity. Its biosynthesis involves the enzymatic formation of a macroamidine, a process previously suggested to require the concerted efforts of a YcaO enzyme (PurCD) and an amidohydrolase (PurAH) in vivo. In vitro, PurCD alone is sufficient to catalyze formation of the macroamidine, but the process is reversible. We set out to probe the role of PurAH in macroamidine formation in vitro. We demonstrate that PurAH is highly selective for macroamidine-containing precursor peptides and cleaves C-terminal of a thiazoline, thus removing the follower peptide. After follower cleavage, macroamidine formation is irreversible, indicating PurAH as the gatekeeper of bottromycin biosynthesis. The structure of PurAH suggests residues involved in catalysis, which were probed through mutagenesis.
Organizational Affiliation: 
Workgroup Structural Biology of Biosynthetic Enzymes, Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research , Saarland University, Campus Geb. E8.1, 66123 Saarbrücken , Germany.