Bactericidal activity of Lys49 and Asp49 myotoxic phospholipases A2 from Bothrops asper snake venom--synthetic Lys49 myotoxin II-(115-129)-peptide identifies its bactericidal region

Eur J Biochem. 1998 Apr 15;253(2):452-61. doi: 10.1046/j.1432-1327.1998.2530452.x.


Mammalian group-II phospholipases A2 (PLA2) of inflammatory fluids display bactericidal properties, which are dependent on their enzymatic activity. This study shows that myotoxins II (Lys49) and III (Asp49), two group-II PLA2 isoforms from the venom of Bothrops asper, are lethal to a broad spectrum of bacteria. Since the catalytically inactive Lys49 myotoxin II isoform has similar bactericidal effects to its catalytically active Asp49 counterpart, a bactericidal mechanism that is independent of an intrinsic PLA2 activity is demonstrated. Moreover, a synthetic 13-residue peptide of myotoxin II, comprising residues 115-129 (common numbering system) near the C-terminal loop, reproduced the bactericidal effect of the intact protein. Following exposure to the peptide or the protein, accelerated uptake of the hydrophobic probe N-phenyl-N-naphthylamine was observed in susceptible but not in resistant bacteria, indicating that the lethal effect was initiated on the bacterial membrane. The outer membrane, isolated lipopolysaccharide (LPS), and lipid A of susceptible bacteria showed higher binding to the myotoxin II-(115-129)-peptide than the corresponding moieties of resistant strains. Bacterial LPS chimeras indicated that LPS is a relevant target for myotoxin II-(115-129)-peptide. When heterologous LPS of the resistant strain was present in the context of susceptible bacteria, the chimera became resistant, and vice versa. Myotoxin II represents a group-II PLA2 with a direct bactericidal effect that is independent of an intrinsic enzymatic activity, but adscribed to the presence of a short cluster of basic/hydrophobic amino acids near its C-terminal loop.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bothrops*
  • Brucella / drug effects*
  • Brucella / ultrastructure
  • Crotalid Venoms / enzymology*
  • Diphtheria Toxoid / chemistry
  • Escherichia / drug effects
  • Escherichia / ultrastructure
  • Fluorometry
  • Group II Phospholipases A2
  • Isoenzymes / pharmacology*
  • Microbial Sensitivity Tests
  • Microscopy, Electron
  • Neurotoxins / pharmacology
  • Peptide Fragments / pharmacology
  • Phospholipases A / pharmacology*
  • Phospholipases A2
  • Reptilian Proteins
  • Salmonella / drug effects
  • Vibrio cholerae / drug effects
  • Vibrio cholerae / ultrastructure


  • Crotalid Venoms
  • Diphtheria Toxoid
  • Isoenzymes
  • Neurotoxins
  • Peptide Fragments
  • Reptilian Proteins
  • Phospholipases A
  • Group II Phospholipases A2
  • Phospholipases A2
  • myotoxin II, Bothrops asper