Modulation of the Susceptibility of Human Erythrocytes to Snake Venom Myotoxic Phospholipases A2: Role of Negatively Charged Phospholipids as Potential Membrane Binding Sites

 

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Autores: Díaz Oreiro, Cecilia, León Montero, Guillermo, Rucavado Romero, Alexandra, Rojas Campos, Norman, Schroit, Alan J., Gutiérrez, José María
Formato: artículo original
Fecha de Publicación:2001
Descripción:Cerrophidion (Bothrops) godmani myotoxins I (CGMT-I) and II (CGMT-II), Asp-49 and Lys-49 phospholipases A(2) (PLA2s), which drastically differ in enzymatic activity, were devoid of direct hemolytic effects on erythrocytes (RBC) from different species despite the fact that enzymatically active CGMT-I was able to hydrolyze RBC membrane phospholipids and disrupt liposomes prepared from RBC lipids. Human RBC did not become susceptible to the toxins after treatment with neuraminidase or after altering membrane fluidity with cholesterol or sublytic concentrations of detergent. Unlike normal RBC, significant hemolysis was induced by CGMT-II and another similar Lys-49 isoform, B. asper MT-II (BAMT-II), in RBC enriched with phosphatidylserine (PS). Hemolysis was greater in RBC preincubated with pyridyldithioethylamine (PDA), a potent inhibitor of aminophospholipid transport. RBC enriched with phosphatidic acid (PA) also became susceptible to the myotoxins but was unaffected by PDA. Cells enriched with phosphatidylcholine (PC) remained resistant to the action of the toxins. BAMT-II also induced damage in black lipid membranes prepared with PS but not PC alone. When RBC binding of BAMT-II was measured by enzyme-linked immunosorbent assay, it was observed that PS- and PA-enriched erythrocytes were always able to capture more toxin than normal and PC-enriched RBC. This effect was significantly improved by PDA (in the case of PS) and it was observed either in the presence or in the absence of calcium in the medium. These data suggest that negatively charged lipids in the outer leaflet of cell membranes constitute myotoxic PLA2 binding sites. The scarcity of anionic phospholipids in the outer leaflet of RBC could explain their resistance to the action of these PLA2s.
País:Kérwá
Institución:Universidad de Costa Rica
Repositorio:Kérwá
OAI Identifier:oai:kerwa.ucr.ac.cr:10669/29479
Acceso en línea:http://www.sciencedirect.com/science/article/pii/S0003986101923860
https://hdl.handle.net/10669/29479
Palabra clave:Animals
Bothrops
Cell Membrane
Crotalid Venoms
Erythrocytes
Group II Phospholipases A2
Humans
Lipid Bilayers
Liposomes
Membrane Fluidity
Neuraminidase
Neurotoxins
Phospholipases A
Phospholipases A2
Phospholipids
Reptilian Proteins
Species Specificity