title: Molecular modeling reveals the novel inhibition mechanism and binding mode of three natural compounds to staphylococcal α-hemolysin.
abstract: α-Hemolysin (α-HL) is a self-assembling, channel-forming toxin that is produced as a soluble monomer by Staphylococcus aureus strains. Until now, α-HL has been a significant virulence target for the treatment of S. aureus infection. In our previous report, we demonstrated that some natural compounds could bind to α-HL. Due to the binding of those compounds, the conformational transition of α-HL from the monomer to the oligomer was blocked, which resulted in inhibition of the hemolytic activity of α-HL. However, these results have not indicated how the binding of the α-HL inhibitors influence the conformational transition of the whole protein during the oligomerization process. In this study, we found that three natural compounds, Oroxylin A 7-O-glucuronide (OLG), Oroxin A (ORA), and Oroxin B (ORB), when inhibiting the hemolytic activity of α-HL, could bind to the "stem" region of α-HL. This was completed using conventional Molecular Dynamics (MD) simulations. By interacting with the novel binding sites of α-HL, the ligands could form strong interactions with both sides of the binding cavity. The results of the principal component analysis (PCA) indicated that because of the inhibitors that bind to the "stem" region of α-HL, the conformational transition of α-HL from the monomer to the oligomer was restricted. This caused the inhibition of the hemolytic activity of α-HL. This novel inhibition mechanism has been confirmed by both the steered MD simulations and the experimental data obtained from a deoxycholate-induced oligomerization assay. This study can facilitate the design of new antibacterial drugs against S. aureus.
authors: Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, China.
authors: Jiazhang
authors: J
authors: Qiu
authors: Dacheng
authors: D
authors: Wang
authors: Yu
authors: Y
authors: Zhang
authors: Jing
authors: J
authors: Dong
authors: Jianfeng
authors: J
authors: Wang
authors: Xiaodi
authors: X
authors: Niu
mesh_terms: D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D001665:Binding Sites; D001688:Biological Products / Q000737:chemistry* / Q000494:pharmacology; D004187:Disaccharides / Q000737:chemistry / Q000494:pharmacology; D047309:Flavones / Q000737:chemistry / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology; D006460:Hemolysin Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D055503:Protein Multimerization / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D001427:Bacterial Toxins; D001688:Biological Products; D004187:Disaccharides; D047309:Flavones; D005419:Flavonoids; D006460:Hemolysin Proteins; C000604116:oroxin B; C021091:staphylococcal alpha-toxin; C080669:5,7-dihydroxy-6-methoxy-2-phenylchromen-4-one