The global spread of methicillin-resistant Staphylococcus aureus (MRSA) underscores the urgent need for novel therapeutics. This study explores the anti-hemolytic activity and mechanism of MGS-3, a semi-synthetic xanthone derivative with potent anti-MRSA properties. Using a multi-tiered approach, we evaluated MGS-3's suppression of S. aureus α-hemolysin (Hla) through in vitro and in vivo models. Mechanistic studies combining gene editing, microscale thermophoresis (MST), and cellular thermal shift assays (CETSA) revealed that MGS-3 directly targets SarA, a key transcriptional regulator of hemolysin biosynthesis. MGS-3 exhibited dose-dependent inhibition of Hla virulence in strains ATCC29213, USA300, and NCTC8325 by repressing hla transcription and expression. Specifically, it downregulated sarA without affecting agrA, disrupting SarA's binding to the hla promoter and thereby reducing Hla-mediated cytotoxicity in A549 and A375 cells. In vivo, MGS-3 reduced skin abscess bacterial loads by 2.1-fold, comparable to ΔsarA (2.3-fold), while mitigating cytokine response and improving histopathology. These results establish SarA suppression as MGS-3's primary anti-virulence mechanism. Notably, MGS-3 maintained low hemolytic activity, highlighting its therapeutic potential. MGS-3 represents a promising candidate for anti-staphylococcal drug development, targeting virulence rather than bacterial viability to potentially curb resistance evolution. This study provides a pharmacodynamic foundation for novel anti-MRSA strategies. IMPORTANCE: The global spread of methicillin-resistant Staphylococcus aureus(MRSA) requires new treatments. The semi-synthetic xanthone derivative MGS-3 inhibits α-hemolysin production by targeting the SarA regulator, reducing virulence. In a murine skin abscess model, it significantly lowered bacterial load and mitigated inflammation. This anti-virulence strategy presents a promising approach to combat MRSA.
Han Bai, Yuehan Zhou, Wenchong Ye et al.· Microbial Pathogenesis· 0 citations
Avian pathogenic Escherichia coli (APEC) induces avian colibacillosis and brings huge economic losses to global poultry production. The small alarmone (p)ppGpp mediates the bacterial stringent response, a vital pathway modulating microbial stress adaptation and pathogenic capacity. The functions of the (p)ppGpp synthase gene relA in APEC pathogenesis remain poorly characterized. In this study, we constructed a relA deletion mutant (ΔrelA) and its complemented strain (CΔrelA). The phenotypic and pathogenic characteristics of these strains were investigated. The results showed that deletion of relA did not significantly affect bacterial growth or motility. However, the ΔrelA strain showed increased susceptibility to aminoglycoside antibiotics. Furthermore, the enhanced interbacterial competition of the mutant was associated with the upregulation of core genes in the type VI secretion system (T6SS). Importantly, relA was essential for APEC adhesion to and invasion of avian DF-1 cells, as well as for colonization and virulence in ducklings, where ΔrelA exhibited significantly attenuated infectivity and reduced bacterial loads in the liver and spleen. Furthermore, transcriptomic analysis revealed that RelA deletion downregulated genes involved in integral components of the membrane, and further assays confirmed compromised membrane integrity in the mutant strain. These findings suggest that RelA maintains membrane integrity, which underpins its contributions to antibiotic resistance and virulence. These findings indicate that relA plays a key role in APEC virulence, antibiotic resistance, and membrane homeostasis, and could provide a theoretical basis for targeting the stringent response as a potential strategy to control avian colibacillosis.
Jiangang Hu, Dossêh Jean Apôtre Afayibo, Chang Liu et al.· Microorganisms· 0 citations
Simulation results show that compared with standard PBFT, Q-PBFT, and APBFT, H-PBFT exhibits significant advantages in consensus latency, throughput, and view switching recovery time, and maintains high system robustness even in complex network environments with malicious nodes.
Zhenhua Wang, Jiangang Hu, Xinmeng Wang et al.· Future Internet· 0 citations