Discovery and Biosynthesis of Persiathiacins: Unusual Polyglycosylated Thiopeptides Active against Multi-drug resistant Tuberculosis

Abstract

AbstractThiopeptides are ribosomally synthesized and posttranslationally modified peptides (RiPPs) that exhibit a range of useful biological activities. Herein, antimicrobial activity screens with a library of Actinobacteria extracts led to discovery of the novel thiopeptide antibiotics persiathiacins A and B, originating from Actinokineospora sp. UTMC 2475 and Actinokineospora sp. UTMC 2448. Persiathiacin A displayed potent activity against methicillin-resistant Staphylococcus aureus (MRSA) and several Mycobacterium tuberculosis strains, including drug-resistant and multidrug-resistant clinical isolates, but no significant toxicity towards an ovarian cancer cell line. On the basis of in vitro translation assays, the observed antibacterial activity could be attributed to inhibition of ribosomal protein biosynthesis. Philipimycin is the only other polyglycosylated thiopeptide reported and nothing is known about its biosynthesis. We therefore sequenced and analysed the genome of Actinokineospora sp. UTMC 2448 to identify the biosynthetic gene cluster responsible for persiathiacin production. Through in vitro and in vivo experiments, we confirmed the role of this gene cluster in persiathiacin biosynthesis and identified a cytochrome P450 enzyme that introduces a site for deoxysugar attachment via thiazole hydroxylation. On the basis of several promising characteristics, persiathiacins A and B are good candidates from which new therapeutics may be engineered.