Recent Advancements in Bottromycin Biosynthesis

Bottromycin is a structurally complex cyclic peptidic compound isolated from Streptomyces bottropensis and related organisms and belongs to the RiPP family of natural products (ribosomally synthesized and post-translationally modified peptides). It exhibits potent antibacterial properties against gram-positive pathogens (including drug resistant strains such as MRSA, MIC 1 mu g/mL and VRE, MIC 0.5 mu g/mL) and mycoplasma. Bottromycin blocks the binding of the aminoacyltRNA to the A-site on the 50S ribosome and hence inhibits protein synthesis. Bottromycins contain structurally diverse post-translational modifications (PTMs) on a small peptide (GPVVVFDC) including a unique macrocyclic amidine, rare.-methylation, terminal thiazole heterocycle, oxidative decarboxylation, and Asp epimerization, among others. It exhibits a precursor peptide organization with a C-terminal follower peptide and a N-terminal core peptide. There are several new studies reported recently which gave detailed insights into the bottromycin biosynthesis pathway. This Account highlights the current advancements in understanding the biosynthetic pathway of bottromycin focusing mainly on the biochemically and structurally characterized enzymes and intricate details of the peptide-protein biophysical interactions. These studies have provided a strong foundation for conducting combinatorial biosynthesis and synthetic biological studies to create novel bottromycin variants for therapeutic applications. 1 Introduction 2 Biosynthetic Pathway for Bottromycin 3 Enzymology of Bottromycin Biosynthesis 3.1 Cleavage of Methionine (BotP) 3.2 Radical SAM Methyltransferases (BotRMT1, BotRMT2, BotRMT3) 3.3 ATP-Dependent YcaO Enzymes 3.3.1 Thiazoline Formation by BotC 3.3.2 Macrolactamidine Formation by BotCD 3.4 Follower Peptide Hydrolysis (BotAH) 3.5 Aspartate Epimerization (BotH) 3.6 Oxidative Decarboxylation (BotCYP) 3.7 O-Methyltransferase (BotOMT) 4 Heterologous Bottromycin Production and Analogue Preparation 5 Summary and Outlook