Flexible loops of thread-like micelles are formed upon interaction of l-α-dimyristoyl-phosphatidylcholine with the biosurfactant surfactin as revealed by cryo-electron tomography
2010; Elsevier BV; Volume: 149; Issue: 1-2 Linguagem: Inglês
10.1016/j.bpc.2010.03.006
ISSN1873-4200
AutoresChristoph Boettcher, Henny Kell, Josef F. Holzwarth, Joachim Vater,
Tópico(s)Protein Structure and Dynamics
ResumoVesicles of l-α-dimyristoyl-phosphatidylcholine (DMPC) are known to disintegrate upon treatment with surfactin, a lipoheptapeptide biosurfactant from Bacillus subtilis OKB 105, as was observed by static light scattering (SLS) and cryo-transmission electron microscopy (cryo-TEM) recently. The lysis of DMPC bilayers occurs strongly dependent on the surfactin concentration according to a three-stage model. Unilamellar DMPC vesicles are disrupted to form sheet-like lamellar intermediates at a moderate surfactant concentration, but undergo a transition towards smaller particles of unknown structure at a higher surfactant concentration according to earlier neutron scattering experiments. Here we present direct structural evidence from cryo-electron tomography data that thread-like micelles with a uniform diameter of 6.5 nm are organized into loops of different sizes at a surfactin concentration of > 15 mol%.
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