Design, Synthesis, and Antibacterial Properties of Dual-Ligand Inhibitors of Acetyl-CoA Carboxylase

There is an urgent demand for the development of new antibiotics due to the increase in drug-resistant pathogenic bacteria. A novel target is the multifunctional enzyme acetyl-CoA carboxylase (ACC), which catalyzes the first committed step in fatty acid synthesis and consists of two enzymes: biotin carboxylase and carboxyltransferase. Covalently attaching known inhibitors against these enzymes with saturated hydrocarbon linkers of different lengths generated dual-ligand inhibitors. Kinetic results revealed that the dual-ligands inhibited the ACC complex in the nanomolar range. Microbiology assays showed that the dual-ligand with a 15-carbon linker did not exhibit any antibacterial activity, while the dual-ligand with a 7-carbon linker displayed broad-spectrum antibacterial activity as well as a decreased susceptibility in the development of bacterial resistance. These results suggest that the properties of the linker are vital for antibacterial activity and show how inhibiting two different enzymes with the same compound increases the overall potency while also impeding the development of resistance

Crystal Structure of Carboxyltransferase from <i>Staphylococcus aureus</i> Bound to the Antibacterial Agent Moiramide B

The dramatic increase in the prevalence of antibiotic-resistant bacteria has necessitated a search for new antibacterial agents against novel targets. Moiramide B is a natural product, broad-spectrum antibiotic that inhibits the carboxyltransferase component of acetyl-CoA carboxylase, which catalyzes the first committed step in fatty acid synthesis. Herein, we report the 2.6 Å resolution crystal structure of moiramide B bound to carboxyltransferase. An unanticipated but significant finding was that moiramide B bound as the enol/enolate. Crystallographic studies demonstrate that the (4<i>S</i>)-methyl succinimide moiety interacts with the oxyanion holes of the enzyme, supporting the notion that an anionic enolate is the active form of the antibacterial agent. Structure–activity studies demonstrate that the unsaturated fatty acid tail of moiramide B is needed only for entry into the bacterial cell. These results will allow the design of new antibacterial agents against the bacterial form of carboxyltransferase