{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,25]],"date-time":"2026-02-25T10:18:01Z","timestamp":1772014681781,"version":"3.50.1"},"reference-count":47,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,2,15]],"date-time":"2026-02-15T00:00:00Z","timestamp":1771113600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Qingyang City Science and Technology Bureau of Gansu Province","award":["GSAU-JSKF-2025-04"],"award-info":[{"award-number":["GSAU-JSKF-2025-04"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Background\/Objectives: Staphylococcus aureus virulence is tightly regulated by the agr (accessory gene regulator) quorum-sensing system. Targeting AgrC, the histidine kinase receptor that serves as a core regulator of agr signaling, represents a promising antivirulence strategy that circumvents conventional bactericidal pressure. Methods: In this study, structure-based virtual screening using AutoDock Vina was performed, followed by molecular dynamics simulations, to identify potent analogs of known AgrC inhibitors. Results: A cyclo[Ala-Phe-OLeu-Phe-D-Leu] exhibiting high binding affinity and stable receptor interaction was selected for further evaluation. Antimicrobial susceptibility testing confirmed that the compound did not inhibit bacterial growth. However, at a concentration of 16 \u00b5g\/mL, it significantly inhibited hemolytic activity with high reproducibility, and the inhibition rate reached 77.60%. Quantitative reverse transcription PCR (RT-qPCR) demonstrated that the compound decreased some key AgrC-mediated genes, including agrC, agrA, saeS, hla, spa, fnbA, and lukS. Conclusions: These findings identify a promising cyclic pentapeptide inhibitor of AgrC that effectively attenuates S. aureus virulence without exerting bactericidal pressure. This work provides a valuable lead compound and offers novel insights for the development of advanced, safe, and effective antivirulence therapeutics.<\/jats:p>","DOI":"10.3390\/antibiotics15020213","type":"journal-article","created":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T11:11:28Z","timestamp":1771240288000},"page":"213","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Cyclic Pentapeptide Inhibits AgrC as a Quorum-Sensing Quenching Agent in Staphylococcus aureus"],"prefix":"10.3390","volume":"15","author":[{"given":"Duiyuan","family":"Ai","sequence":"first","affiliation":[{"name":"College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Huanhuan","family":"Duan","sequence":"additional","affiliation":[{"name":"College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiahao","family":"Yao","sequence":"additional","affiliation":[{"name":"College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Mai, Z., Li, J., Zhan, Z., Tian, X., Hou, W., He, M., and Shi, C. (2025). Metabolic Master Switch: Pyruvate Carboxylase Fuels Antimicrobial Resistance and Virulence in Foodborne Staphylococcus aureus. Foods, 14.","DOI":"10.3390\/foods14152566"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1038\/s41579-018-0147-4","article-title":"Methicillin-resistant Staphylococcus aureus: An overview of basic and clinical research","volume":"17","author":"Turner","year":"2019","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1016\/S0966-842X(01)02175-8","article-title":"The emergence and evolution of methicillin-resistant Staphylococcus aureus","volume":"9","author":"Hiramatsu","year":"2001","journal-title":"Trends Microbiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"658","DOI":"10.1016\/j.eururo.2022.08.023","article-title":"Re: Global Burden of Bacterial Antimicrobial Resistance in 2019: A Systematic Analysis","volume":"82","author":"Wagenlehner","year":"2022","journal-title":"Eur. Urol."},{"key":"ref_5","unstructured":"GBD 2019 Antimicrobial Resistance Collaborators (2022). Global mortality associated with 33 bacterial pathogens in 2019: A systematic analysis for the Global Burden of Disease Study 2019. Lancet, 400, 2221\u20132248."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1128\/CMR.00134-14","article-title":"Staphylococcus aureus infections: Epidemiology, pathophysiology, clinical manifestations, and management","volume":"28","author":"Tong","year":"2015","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Foster, T.J. (2019). Surface Proteins of Staphylococcus aureus. Microbiol. Spectr., 7.","DOI":"10.1128\/microbiolspec.GPP3-0046-2018"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Wang, Y., Yin, T., Qian, M., Ismail, B.B., Zou, Z., Zhang, X., He, Q., and Guo, M. (2025). Integrated Phenotypic and Transcriptomic Analyses Unveil the Antibacterial Mechanism of Punicalagin Against Methicillin-Resistant Staphylococcus aureus (MRSA). Foods, 14.","DOI":"10.3390\/foods14213589"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4206","DOI":"10.1128\/IAI.71.7.4206-4211.2003","article-title":"Mutation of sarA in Staphylococcus aureus limits biofilm formation","volume":"71","author":"Beenken","year":"2003","journal-title":"Infect. Immun."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Prince, A., and Wong, F.L.T. (2020). Consequences of Metabolic Interactions during Staphylococcus aureus Infection. Toxins, 12.","DOI":"10.3390\/toxins12090581"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1088","DOI":"10.1099\/mic.0.000983","article-title":"The general stress response of Staphylococcus aureus promotes tolerance of antibiotics and survival in whole human blood","volume":"166","author":"Ranganathan","year":"2020","journal-title":"Microbiology"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"318","DOI":"10.1016\/S1473-3099(17)30753-3","article-title":"Discovery, research, and development of new antibiotics: The WHO priority list of antibiotic-resistant bacteria and tuberculosis","volume":"18","author":"Tacconelli","year":"2018","journal-title":"Lancet Infect. Dis."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"22684","DOI":"10.1021\/acsomega.0c02294","article-title":"Mechanisms and Control Measures of Mature Biofilm Resistance to Antimicrobial Agents in the Clinical Context","volume":"5","author":"Li","year":"2020","journal-title":"ACS Omega"},{"key":"ref_14","first-page":"147","article-title":"Anti-virulence Strategies to Target Bacterial Infections","volume":"Volume 398","author":"Dersch","year":"2016","journal-title":"How to Overcome the Antibiotic Crisis; Current Topics in Microbiology and Immunology"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Selvarajan, R., Obize, C., Sibanda, T., Abia, A.L.K., and Long, H. (2022). Evolution and Emergence of Antibiotic Resistance in Given Ecosystems: Possible Strategies for Addressing the Challenge of Antibiotic Resistance. Antibiotics, 12.","DOI":"10.3390\/antibiotics12010028"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1038\/nrmicro2974","article-title":"The gut microbiota\u2014Masters of host development and physiology","volume":"11","author":"Sommer","year":"2013","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"RP89098","DOI":"10.7554\/eLife.89098","article-title":"Quorum-sensing agr system of Staphylococcus aureus primes gene expression for protection from lethal oxidative stress","volume":"12","author":"Podkowik","year":"2024","journal-title":"Elife"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2027","DOI":"10.1126\/science.276.5321.2027","article-title":"Bacterial interference caused by autoinducing peptide variants","volume":"276","author":"Ji","year":"1997","journal-title":"Science"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1146\/annurev-micro-102215-095708","article-title":"Staphylococcus aureus RNAIII and Its Regulon Link Quorum Sensing, Stress Responses, Metabolic Adaptation, and Regulation of Virulence Gene Expression","volume":"70","author":"Bronesky","year":"2016","journal-title":"Annu. Rev. Microbiol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2561827","DOI":"10.1080\/21505594.2025.2561827","article-title":"The global regulator SpoVG modulates Staphylococcus aureus virulence through Agr-dependent pathways","volume":"16","author":"Ma","year":"2025","journal-title":"Virulence"},{"key":"ref_21","first-page":"5","article-title":"Polysaccharide intercellular adhesin in biofilm: Structural and regulatory aspects","volume":"10","author":"Arciola","year":"2015","journal-title":"Front. Cell Infect. Microbiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"107670","DOI":"10.1016\/j.fbio.2025.107670","article-title":"Targeting the two-component Agr system in Staphylococcus aureus: Molecular docking and dynamics insights into natural compound inhibition","volume":"73","author":"Praisy","year":"2025","journal-title":"Food Biosci."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Ma, X., Ma, J., Liu, J., Hao, H., Hou, H., and Zhang, G. (2024). Inhibitory Effect of Phenethyl Isothiocyanate on the Adhesion and Biofilm Formation of Staphylococcus aureus and Application on Beef. Foods, 13.","DOI":"10.3390\/foods13213362"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"7869","DOI":"10.1021\/ja3112115","article-title":"Highly potent inhibitors of quorum sensing in Staphylococcus aureus revealed through a systematic synthetic study of the group-III autoinducing peptide","volume":"135","author":"Stacy","year":"2013","journal-title":"J. Am. Chem. Soc."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"712","DOI":"10.1111\/cbdd.13497","article-title":"Proteoliposome-based model for screening inhibitors targeting histidine kinase AgrC","volume":"93","author":"Zhang","year":"2019","journal-title":"Chem. Biol. Drug Des."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"4385","DOI":"10.1016\/j.bmcl.2008.06.066","article-title":"Synthesis and antitumor activity of cyclodepsipeptide zygosporamide and its analogues","volume":"18","author":"Wang","year":"2008","journal-title":"Bioorg Med. Chem. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1982","DOI":"10.1021\/acschembio.6b00120","article-title":"Structure-Function Analyses of a Staphylococcus epidermidis Autoinducing Peptide Reveals Motifs Critical for AgrC-type Receptor Modulation","volume":"11","author":"Yang","year":"2016","journal-title":"ACS Chem. Biol."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Nielsen, A., M\u00e5nsson, M., Bojer, M.S., Gram, L., Larsen, T.O., Novick, R.P., Frees, D., Fr\u00f8ki\u00e6r, H., and Ingmer, H. (2014). Solonamide B inhibits quorum sensing and reduces Staphylococcus aureus mediated killing of human neutrophils. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0084992"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"484","DOI":"10.1021\/acsinfecdis.9b00002","article-title":"Simplified Autoinducing Peptide Mimetics with Single-Nanomolar Activity Against the Staphylococcus aureus AgrC Quorum Sensing Receptor","volume":"5","author":"Vasquez","year":"2019","journal-title":"ACS Infect. Dis."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Vuki\u0107, D., Lon\u010dar, B., Pezo, L., and Vuki\u0107, V. (2025). Application of Predictive Modeling and Molecular Simulations to Elucidate the Mechanisms Underlying the Antimicrobial Activity of Sage (Salvia officinalis L.) Components in Fresh Cheese Production. Foods, 14.","DOI":"10.3390\/foods14132164"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1157","DOI":"10.1080\/07391102.2023.2201863","article-title":"Structure-based virtual screening and molecular dynamics approaches to identify new inhibitors of Staphylococcus aureus sortase A","volume":"42","author":"Mahmood","year":"2024","journal-title":"J. Biomol. Struct. Dyn."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1007\/978-1-0716-1767-0_9","article-title":"Computational Methods for Structure-Based Drug Design Through System Biology","volume":"2385","author":"Kaushik","year":"2022","journal-title":"Methods Mol. Biol."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Khayat, M.T., Abbas, H.A., Ibrahim, T.S., Khayyat, A.N., Alharbi, M., Darwish, K.M., Elhady, S.S., Khafagy, E.S., Safo, M.K., and Hegazy, W.A.H. (2022). Anti-Quorum Sensing Activities of Gliptins against Pseudomonas aeruginosa and Staphylococcus aureus. Biomedicines, 10.","DOI":"10.3390\/biomedicines10051169"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1556","DOI":"10.1055\/s-0032-1315042","article-title":"Quorum quenching and antimicrobial activity of goldenseal (Hydrastis canadensis) against methicillin-resistant Staphylococcus aureus (MRSA)","volume":"78","author":"Cech","year":"2012","journal-title":"Planta Med."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"127071","DOI":"10.1016\/j.micres.2022.127071","article-title":"Natural flavone hispidulin protects mice from Staphylococcus aureus pneumonia by inhibition of alpha-hemolysin production via targeting AgrA(C)","volume":"261","author":"Ren","year":"2022","journal-title":"Microbiol. Res."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Pant, N., Miranda-Hernandez, S., Rush, C., Warner, J., and Eisen, D.P. (2022). Effect of savirin in the prevention of biofilm-related Staphylococcus aureus prosthetic joint infection. Front. Pharmacol., 13.","DOI":"10.3389\/fphar.2022.989417"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1009","DOI":"10.1093\/infdis\/jiy259","article-title":"Application of an agr-Specific Antivirulence Compound as Therapy for Staphylococcus aureus-Induced Inflammatory Skin Disease","volume":"218","author":"Baldry","year":"2018","journal-title":"J. Infect. Dis."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Otto, M. (2023). Critical Assessment of the Prospects of Quorum-Quenching Therapy for Staphylococcus aureus Infection. Int. J. Mol. Sci., 24.","DOI":"10.3390\/ijms24044025"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"107465","DOI":"10.1016\/j.bioorg.2024.107465","article-title":"A review of chemical signaling mechanisms underlying quorum sensing and its inhibition in Staphylococcus aureus","volume":"148","author":"Vadakkan","year":"2024","journal-title":"Bioorganic Chem."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1218","DOI":"10.1073\/pnas.96.4.1218","article-title":"Structure-activity analysis of synthetic autoinducing thiolactone peptides from Staphylococcus aureus responsible for virulence","volume":"96","author":"Mayville","year":"1999","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"e2202661119","DOI":"10.1073\/pnas.2202661119","article-title":"Reconstitution of the S. aureus agr quorum sensing pathway reveals a direct role for the integral membrane protease MroQ in pheromone biosynthesis","volume":"119","author":"Zhao","year":"2022","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Liu, J., Wu, H., Ao, X., Hao, H., Bi, J., Hou, H., and Zhang, G. (2022). Characterization of the Inclusion Complexes of Isothiocyanates with \u03b3-Cyclodextrin for Improvement of Antibacterial Activities against Staphylococcus aureus. Foods, 11.","DOI":"10.3390\/foods11010060"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1950","DOI":"10.1002\/prot.22711","article-title":"Improved side-chain torsion potentials for the Amber ff99SB protein force field","volume":"78","author":"Piana","year":"2010","journal-title":"Proteins"},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Tam, K., and Torres, V.J. (2019). Staphylococcus aureus Secreted Toxins and Extracellular Enzymes. Microbiol. Spectr., 7.","DOI":"10.1128\/microbiolspec.GPP3-0039-2018"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"e202200096","DOI":"10.1002\/ijch.202200096","article-title":"Chemical and biomolecular insights into the Staphylococcus aureus agr quorum sensing system: Current progress and ongoing challenges","volume":"63","author":"Polaske","year":"2023","journal-title":"Isr. J. Chem."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"2705","DOI":"10.1021\/acs.jmedchem.9b00798","article-title":"Structure-Activity Relationship Studies of Small Molecule Modulators of the Staphylococcal Accessory Gene Regulator","volume":"63","author":"Horswill","year":"2020","journal-title":"J. Med. Chem."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1007\/s10822-016-0005-2","article-title":"Exploring the stability of ligand binding modes to proteins by molecular dynamics simulations","volume":"31","author":"Liu","year":"2017","journal-title":"J. Comput. Aided Mol. 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