AtlA modulator 4a (Anhui Medical University)

Novel benzothiazole aryl ureas were designed and synthesized as anti-MRSA agents targeting peptidoglycan (PG) hydrolases (autolysins). Structural simplification of prior benzothiazole-urea hybrids yielded compounds 4a, 7a and 11a bearing p-CF₃ on phenyl ring demonstrating narrow-spectrum activity against Gram-positive bacteria including clinical methicillin-resistant S. aureus (MRSA). The primary autolysin in S. aureus, AtlA, mediates peptidoglycan hydrolase activity critical for bacterial growth, division, and cell wall remodeling. Mechanistic studies revealed that 4a down-regulated autolysin-related genes RNAIII and walR, disrupting peptidoglycan homeostasis. Knockout of atlA (a key autolysin gene) impaired 4a's efficacy, confirming autolysins as critical targets. Docking indicated that 4a binds to AtlA via hydrogen bonds, Pi-Pi, and hydrophobic interactions. In vivo, 4a significantly reduced bacterial load in a murine abdominal infection model, outperforming vancomycin at 10 mg/kg with lower cytotoxicity. Additionally, 4a disrupted MRSA biofilms, suppressed hemolytic toxin production, and alleviated inflammation in infected mice. These findings underscore AtlA as a promising therapeutic target and highlight benzothiazole phenyl urea as a scaffold for developing innovative anti-staphylococcal agents.