title: Interfacial surface charge and free accessibility to the PLA2-active site-like region are essential requirements for the activity of Lys49 PLA2 homologues.
abstract: Lys49 phospholipase A2 homologues are highly myotoxic and cause extensive tissue damage but do not display hydrolytic activity towards natural phospholipids. The binding of heparin, heparin derivatives and polyanionic compounds such as suramin result in partial inhibition (up to 60%) of the myotoxic effects due to a change in the overall charge of the interfacial surface. In vivo experiments demonstrate that polyethylene glycol inhibits more than 90% of the myotoxic effects without exhibiting secondary toxic effects. The crystal structure of bothropstoxin-I complexed with polyethylene glycol reveals that this inhibition is due to steric hindrance of the access to the PLA2-active site-like region. These two inhibitory pathways indicate the roles of the overall surface charge and free accessibility to the PLA2-active site-like region in the functioning of Lys49 phospholipases A2 homologues. Molecular dynamics simulations, small angle X-ray scattering and structural analysis indicate that the oligomeric states both in solution and in the crystalline states of Lys49 phospholipases A2 are principally mediated by hydrophobic contacts formed between the interfacial surfaces. These results provide the framework for the potential application of both clinically approved drugs for the treatment of Viperidae snakebites.
authors.affiliation: Department of Physics, IBILCE/UNESP, Cristovão Colombo 2265, São José do Rio Preto, SP 15054-000, Brazil.
authors.forename: Mário T
authors.initials: MT
authors.lastname: Murakami
authors.forename: Magno M
authors.initials: MM
authors.lastname: Viçoti
authors.forename: José R B
authors.initials: JR
authors.lastname: Abrego
authors.forename: Marco R
authors.initials: MR
authors.lastname: Lourenzoni
authors.forename: Adélia C O
authors.initials: AC
authors.lastname: Cintra
authors.forename: Emerson Z
authors.initials: EZ
authors.lastname: Arruda
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Tomaz
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Melo
authors.forename: Raghuvir K
authors.initials: RK
authors.lastname: Arni
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D017837:Bothrops; D003402:Creatine Kinase / Q000378:metabolism; D003435:Crotalid Venoms / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D003460:Crystallization; D004305:Dose-Response Relationship, Drug; D004336:Drug Antagonism; D054501:Group II Phospholipases A2; D008958:Models, Molecular; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009336:Necrosis / Q000139:chemically induced; D009498:Neurotoxins / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D010741:Phospholipases A / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D054467:Phospholipases A2; D011092:Polyethylene Glycols / Q000494:pharmacology; D017433:Protein Structure, Secondary; D030162:Reptilian Proteins; D053838:Scattering, Small Angle; D013498:Suramin / Q000494:pharmacology; D013499:Surface Properties / Q000187:drug effects; D014965:X-Rays
chemical_list: D003435:Crotalid Venoms; D009498:Neurotoxins; D030162:Reptilian Proteins; D011092:Polyethylene Glycols; D013498:Suramin; D003402:Creatine Kinase; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054467:Phospholipases A2; C061056:myotoxin II, Bothrops asper