Shisong Jing,Li Wang,Tiedong Wang,Lianghai Fan,Lin Chen,Hua Xiang,Yan Shi,Dacheng Wang
Methicillin-resistant Staphylococcus aureus is one of the leading causes of community and nosocomial infections, which has created the urgent need for innovative anti-infective agents to control MRSA-associated infections. A conserved serine protease , caseinolytic peptidase P (ClpP) in Staphylococcus aureus is highly associated with pathogenicity and has been claimed to be a novel antimicrobial target. We aim to search suitable inhibitors of ClpP to attenuate the virulence of MRSA and combat their infections in vivo . Over 500 natural compounds were pre-screened via fluorescence resonance energy transfer using the Suc-LY-AMC substrate. The binding of myricetin to ClpP was determined and the mechanism of action was elucidated by thermal shift assay, surface plasmon resonance , and molecular dynamics simulations. The therapeutic effects of myricetin on S. aureus infection were further investigated using a S. aureus -induced pneumonia model. We revealed that myricetin could effectively block the activity of ClpP without disturbing the growth of the bacteria and the Gln-47 and Met-31 residues were necessary for myricetin binding to ClpP. Importantly, myricetin attenuated the pathogenicity of S. aureus in vivo , while improving the efficacy of the traditional antibiotic oxacillin against MRSA infection and protecting mice from fatal lung infections caused by MRSA. These findings indicate that myricetin has the potential to be applied in the pharmaceutical industry as a promising therapeutic agent.
IntroductionMethicillin resistant Staphylococcus aureus, MRSA, is a major cause of hospital acquired infections and poses a serious therapeutic challenge because of multidrug resistance and potent virulence. Targeting virulence rather than bacterial growth may provide an alternative strategy to combat MRSA infection. This study investigated polydatin, a stilbenoid glucoside from Polygonum cuspidatum, as a potential antivirulence agent targeting caseinolytic protease P, ClpP.MethodsClpP inhibitory activity was evaluated by enzymatic assay. The effects of polydatin on bacterial growth, hemolytic activity, virulence gene expression, adhesion to fibrinogen, and host cell invasion were assessed in vitro. Target engagement was examined by thermal shift assay, fluorescence quenching, and computational simulation. Therapeutic efficacy was evaluated in a murine pneumonia model.ResultsPolydatin showed limited antibacterial activity but significantly inhibited ClpP and reduced the expression of key virulence factors, including Hla, PVL, and RNAIII. It also impaired bacterial adhesion to fibrinogen and invasion of host cells. Binding studies supported the interaction between polydatin and ClpP. In vivo, polydatin markedly alleviated S. aureus induced pneumonia, as shown by reduced lung bacterial burden, lower inflammatory cytokine levels, and attenuated tissue injury.DiscussionPolydatin attenuates MRSA pathogenicity by targeting ClpP associated virulence regulation rather than bacterial viability. These findings identify polydatin as a promising antivirulence candidate and provide a basis for developing alternative therapeutic strategies against MRSA infections.
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