Abstract
We have used high resolution AFM based dynamic force spectroscopy to investigate peptide-lipid membrane interactions by measuring the detachment (last-rupture) force distribution, P(F), and the corresponding force dependent rupture rate, k(F), for two different peptides and lipid bilayers. The measured quantities, which differed considerably for different peptides, lipid-membranes, AFM tips (prepared under identical conditions), and retraction speeds of the AFM cantilever, could not be described in terms of the standard theory, according to which detachment occurs along a single pathway, corresponding to a diffusive escape process across a free energy barrier. In particular, the prominent retraction speed dependence of k(F) was a clear indication that peptide-lipid membrane dissociation occurs stochastically along several detachment pathways. Thereby, we have formulated a general theoretical approach for describing P(F) and k(F), by assuming that peptide detachment from lipid membranes occurs, with certain probability, along a few dominant diffusive pathways. This new method was validated through a consistent interpretation of the experimental data. Furthermore, we have found that for moderate retraction speeds at intermediate force values, k(F) exhibits catch-bond behavior (i.e. decreasing detachment rate with increasing force). According to the proposed model this behavior is due to the stochastic mixing of individual detachment pathways which do not convert or cross during rupture. To our knowledge, such catch-bond mechanism has not been proposed and demonstrated before for a peptide-lipid interaction.
Highlights
2252-Plat The Small Heat Shock Proteins, HSPB1 and HSPB6, Have the Ability to Get Inserted into Lipid Membranes Antonio De Maio1,2, David M
Increasing evidence has indicated that heat shock proteins (HSP) escape their cytosolic environment acting as signaling agents in the extracellular fluid
We report that a member of the small hsp family, HSPB1 (Hsp27), was found to be associated with exosomes and apparently inserted in the vesicle membrane
Summary
2252-Plat The Small Heat Shock Proteins, HSPB1 and HSPB6, Have the Ability to Get Inserted into Lipid Membranes Antonio De Maio1,2, David M. 2251-Plat Multiple Stochastic Pathways in Forced Peptide-Lipid Membrane Detachment Milica Utjesanovic1, Tina R. We have used high resolution AFM based dynamic force spectroscopy to investigate peptide-lipid membrane interactions by measuring the detachment (lastrupture) force distribution, P(F), and the corresponding force dependent rupture rate, k(F), for two different peptides and lipid bilayers. The prominent retraction speed dependence of k(F) was a clear indication that peptide-lipid membrane dissociation occurs stochastically along several detachment pathways.
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