Effect of unsaturated bonds in the sn-2 acyl chain of phosphatidylcholine on the membrane-damaging action of Clostridium perfringens alpha-toxin toward liposomes

Biochim Biophys Acta. 2007 Nov;1768(11):2940-5. doi: 10.1016/j.bbamem.2007.08.016. Epub 2007 Aug 24.


Clostridium perfringens alpha-toxin degrades phosphatidylcholine (PC) in the bilayer of liposomes and destroys the membrane. The effect of the type and position of unsaturation in the fatty acyl chain of PC (18:0/18:1 PC) synthesized on the toxin-induced leakage of carboxyfluorescein (CF) from PC liposomes was examined. Differential scanning calorimetry showed that the phase transition temperature (T(m)) was minimal when the triple bond was positioned at C (9) in the sn-2 acyl chain. The toxin-induced CF leakage decreased with the migration of the bond from C (9) to either end of the acyl chain in PC. The PC containing the cis-double bond had a similar T(m) to that with the triple bond, but a lower value than the PC containing the trans-double bond. Furthermore, the toxin-induced leakage from liposomes composed of PC containing the cis-double bond resembled that with PC having the triple bond and was greater than that from liposomes with PC having the trans-double bond. The binding of a H148G mutant to PC liposomes showed a reciprocal relationship in terms of the T(m) value of PC containing the triple bond. These results indicate that the toxin-induced membrane damage is closely related to membrane fluidity in liposomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Toxins / toxicity*
  • Calcium-Binding Proteins / toxicity*
  • Cell Membrane / drug effects*
  • Cell Membrane / metabolism
  • Liposomes / chemistry*
  • Liposomes / metabolism
  • Membrane Fluidity
  • Phase Transition
  • Phosphatidylcholines / chemistry*
  • Phosphatidylcholines / metabolism
  • Temperature
  • Type C Phospholipases / toxicity*


  • Bacterial Toxins
  • Calcium-Binding Proteins
  • Liposomes
  • Phosphatidylcholines
  • Type C Phospholipases
  • alpha toxin, Clostridium perfringens