Dipeptide-Based Metabolic Labeling of Bacterial Cells for Endogenous Antibody Recruitment

[Image: see text] The number of antibiotic-resistant bacterial infections has increased dramatically over the past decade. To combat these pathogens, novel antimicrobial strategies must be explored and developed. We previously reported a strategy based on hapten-modified cell wall analogues to induce recruitment of endogenous antibodies to bacterial cell surfaces. Cell surface remodeling using unnatural single d-amino acid cell wall analogues led to modification at the C-terminus of the peptidoglycan stem peptide. During peptidoglycan processing, installed hapten-displaying amino acids can be subsequently removed by cell wall enzymes. Herein, we disclose a two-step dipeptide peptidoglycan remodeling strategy aimed at introducing haptens at an alternative site within the stem peptide to improve retention and diminish removal by cell wall enzymes. Through this redesigned strategy, we determined size constraints of peptidoglycan remodeling and applied these constraints to attain hapten–linker conjugates that produced high levels of antibody recruitment to bacterial cell surfaces.