Basic phospholipase A2 homolog BnSP-7

UniProtKB accession:  Q9IAT9

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UniProtKB description:  Snake venom phospholipase A2 (PLA2) that lacks enzymatic activity (PubMed:10860537). Is myotoxic and displays edema-inducing activity (PubMed:10860537, PubMed:9972319). Displays bactericidal activity and promotes the blockage of the neuromuscular contraction of the chick biventer cervicis muscle (PubMed:10860537, PubMed:9972319). Also disrupts artificial membranes, and provokes tissue damages characterized by edema, necrosis and inflammation (PubMed:10860537, PubMed:9972319). May act as pro-inflammatory mediators, inducing metalloproteinase and cytokine production from the inflammatory and satellite cells (PubMed:19673103). A model of myotoxic mechanism has been proposed: an apo Lys49-PLA2 is activated by the entrance of a hydrophobic molecule (e.g. fatty acid) at the hydrophobic channel of the protein leading to a reorientation of a monomer (By similarity). This reorientation causes a transition between 'inactive' to 'active' states, causing alignment of C-terminal and membrane-docking sites (MDoS) side-by-side and putting the membrane-disruption sites (MDiS) in the same plane, exposed to solvent and in a symmetric position for both monomers (By similarity). The MDoS region stabilizes the toxin on membrane by the interaction of charged residues with phospholipid head groups (By similarity). Subsequently, the MDiS region destabilizes the membrane with penetration of hydrophobic residues (By similarity). This insertion causes a disorganization of the membrane, allowing an uncontrolled influx of ions (i.e. calcium and sodium), and eventually triggering irreversible intracellular alterations and cell death (By similarity).