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Title: Identification and characterization of a phospholipase A2 from the venom of the Saw-scaled viper: Novel bactericidal and membrane damaging activities
Authors: Perumal Samy, R. 
Gopalakrishnakone, P.
Bow, H.
Puspharaj, P.N.
Chow, V.T.K.
Keywords: Bactericidal activity
Echis carinatus
Phospholipase A2
Snake venom
Issue Date: Dec-2010
Citation: Perumal Samy, R., Gopalakrishnakone, P., Bow, H., Puspharaj, P.N., Chow, V.T.K. (2010-12). Identification and characterization of a phospholipase A2 from the venom of the Saw-scaled viper: Novel bactericidal and membrane damaging activities. Biochimie 92 (12) : 1854-1866. ScholarBank@NUS Repository.
Abstract: Phospholipase A2 (PLA2), a common toxic component of snake venom, has been implicated in various pharmacological effects. In this study, a basic myotoxic PLA2, named EcTx-I was isolated from Echis carinatus snake venom by using gel filtration on Superdex G-75, and reverse phase HPLC on C18 and C8 Sepharose columns. PLA2, EcTx-I was 13,861.72 molecular weight as estimated by MALDI-TOF (15 kD by SDS-PAGE), and consisted of 121 amino acid residues cross-linked by seven disulfide bonds. The N-terminal sequences revealed significant homology with basic myotoxic PLA 2s from other snake venoms. The purified PLA2 EcTx-I was evaluated (250 μg/ml) for bactericidal activity of a wide variety of human pathogens against Burkholderia pseudomallei (KHW&TES), Enterobacter aerogenes, Escherichia coli, Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa and Staphylococcus aureus. EcTx-I showed strong antibacterial activity against B. pseudomallei (KHW) and E. aerogenes among the tested bacteria. Other Gram-negative and Gram-positive bacteria showed only a moderate effect. However, the Gram-positive bacterium E. aerogenes failed to show any effect on EcTx-I protein at tested doses. The most significant bacteriostatic and bactericidal effect of EcTx-I was observed at MICs of >15 μg/ml against (B. pseudomallei, KHW) and MICs >30 μg/ml against E. aerogenes. Mechanisms of bactericidal and membrane damaging effects were proved by ultra-structural analysis. EcTx-I was able to induce cytotoxicity on THP-1 cells in vitro as well as lethality in BALB/c mice. EcTx-I also induced mild myotoxic effects on mouse skin, but was devoid of hemolytic effects on human erythrocytes up to 500 μg/ml. It is shown that the toxic effect induced by E. carinatus venom is due to the presence of myotoxic PLA2 (EcTx-I). The result also corroborates the hypothesis of an association between toxic and enzymatic domains. In conclusion, EcTx-I displays a heparin binding C-terminal region, which is probably responsible for the cytotoxic and bactericidal effects. © 2010 Elsevier Masson SAS. All rights reserved.
Source Title: Biochimie
ISSN: 03009084
DOI: 10.1016/j.biochi.2010.07.012
Appears in Collections:Staff Publications

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