Abstract
Daptomycin is a cyclic lipodepsipeptide antibiotic used to treat infections caused by Gram-positive pathogens, including multi-drug resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). The emergence of daptomycin-resistant bacterial strains has renewed interest in generating daptomycin analogs. Previous studies have shown that replacing the tryptophan of daptomycin with aromatic groups can generate analogs with enhanced potency. Additionally, we have demonstrated that aromatic prenyltransferases can attach diverse groups to the tryptophan of daptomycin. Here, we report the use of the prenyltransferase CdpNPT to derivatize the tryptophan of daptomycin with a library of benzylic and heterocyclic pyrophosphates. An analytical-scale study revealed that CdpNPT can transfer various aromatic groups onto daptomycin. Subsequent scaled-up and purified reactions indicated that the enzyme can attach aromatic groups to N1, C2, C5 and C6 positions of Trp1 of daptomycin. In vitro antibacterial activity assays using six of these purified compounds identified aromatic substituted daptomycin analogs show potency against both daptomycin-susceptible and resistant strains of Gram-positive bacteria. These findings suggest that installing aromatic groups on the Trp1 of daptomycin can lead to the generation of potent daptomycin analogs.