Abstract
The multisubunit acetyl-CoA carboxylase, which catalyzes the first committed step in fatty acid biosynthesis, is broadly conserved among bacteria. Its rate-limiting role in formation of fatty acids makes this enzyme an attractive target for the design of novel broad-spectrum antibacterials. However, no potent inhibitors have been discovered so far. This report describes the identification and characterization of highly potent bacterial acetyl-CoA carboxylase inhibitors with antibacterial activity for the first time. We demonstrate that pseudopeptide pyrrolidine dione antibiotics such as moiramide B inhibit the Escherichia coli enzyme at nanomolar concentrations. Moiramide B targets the carboxyltransferase reaction of this enzyme with a competitive inhibition pattern versus malonyl-CoA (K(i) value = 5 nm). Inhibition at nanomolar concentrations of the pyrrolidine diones is also demonstrated using recombinantly expressed carboxyltransferases from other bacterial species (Staphylococcus aureus, Streptococcus pneumoniae, and Pseudomonas aeruginosa). We isolated pyrrolidine dione-resistant strains of E. coli, S. aureus, and Bacillus subtilis, which contain mutations within the carboxyltransferase subunits AccA or AccD. We demonstrate that such mutations confer resistance to pyrrolidine diones. Inhibition values (IC(50)) of >100 microm regarding an eukaryotic acetyl-CoA carboxylase from rat liver indicate high selectivity of pyrrolidine diones for the bacterial multisubunit enzyme. The natural product moiramide B and synthetic analogues show broad-spectrum antibacterial activity. The knowledge of the target and the availability of facile assays using carboxyltransferases from different pathogens will enable evaluation of the antibacterial potential of the pyrrolidine diones as a promising antibacterial compound class acting via a novel mode of action.
Highlights
The fatty acid synthesis (FAS)1 in living organisms comprises a repeated cycle of reactions involving the condensation, reduction, dehydration, and subsequent reduction of carboncarbon bonds
We demonstrate that pseudopeptide pyrrolidine dione antibiotics such as moiramide B inhibit the Escherichia coli enzyme at nanomolar concentrations
We show that the pseudopeptide pyrrolidine dione antibiotics moiramide B (CPD1) and andrimid (CPD5; Fig. 2) (26 –28) act by inhibiting the carboxyltransferases of bacterial acetyl-CoA carboxylase (ACC)
Summary
The fatty acid synthesis (FAS) in living organisms comprises a repeated cycle of reactions involving the condensation, reduction, dehydration, and subsequent reduction of carboncarbon bonds. Inhibitors of the enoylacyl carrier protein (enoyl-ACP) reductase FabI, such as triclosan [7, 8], or of the condensing enzyme isoforms FabF/ FabB, such as cerulenin [9, 10], raised the hope that bacterial FAS represents a novel yet under-explored target area for the discovery of novel antibiotics. Studies in Bacillus subtilis indicated that the product of the ACC-catalyzed reaction malonyl-CoA plays major roles in regulating the expression of other FAS enzymes [21]. These findings suggest that the bacterial acetyl-CoA carboxylase could be an appropriate target for the design of novel broad-spectrum antibacterials. Reaction intermediates and bisubstrate analogues without antibacterial activity have been published so far, representing moderate inhibitors of the two partial reactions of ACC [24, 25]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
