Artesunate Perturbs GTP Binding of the Conserved GTPase Obg Thereby Alleviating Antibiotic Resistance in Methicillin-Resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen that causes various secondary infections among hospital-associated patients. The pathogen is challenging to treat due to its resistance to a wide spectrum of antibiotics, including the last-resort antibiotic vancomycin and newly developed drugs, such as linezolid and daptomycin. While the invention of entirely new drugs to combat MRSA infection seems almost impossible, potentiating the efficacy of conventional antibiotics is critical. Our article explores the novel application of the antimalarial drug artesunate, which enhances the efficacy of vancomycin and cefoxitin in treating MRSA infections. We focused on ObgSa, a conserved GTPase in MRSA, and found that artesunate selectively binds to its GTP-binding pocket. We further evaluated the GTP-binding activity and metal dependence (specifically, Mg2+) of this conserved GTPase. In silico analysis identified several threonine residues essential for GTP binding, which were subsequently mutated to assess their role in GTP binding. As shown in the analysis, these mutations significantly impacted both the GTP binding and hydrolysis functions of ObgSa. Notably, these threonine residues were also crucial for artesunate binding within the GTP-binding domain. When the effect of artesunate was assessed, the drug competitively inhibited GTP binding and hydrolysis of the GTPase. This result was manifested as reduced antibiotic tolerance, disruption of biofilms, and a decrease in persister cells─critical factors in chronic infections. In summary, our research presents an innovative strategy to combat antimicrobial resistance through artesunate, highlighting its potential effectiveness in eradicating infections.