title: Self-assembled alpha-hemolysin pores in an S-layer-supported lipid bilayer.
abstract: The effects of a supporting proteinaceous surface-layer (S-layer) from Bacillus coagulans E38-66 on a 1,2-diphytanoyl-sn-glycero-3-phosphatidylcholine (DPhPC) bilayer were investigated. Comparative voltage clamp studies on plain and S-layer supported DPhPC bilayers revealed no significant difference in the capacitance. The conductance of the composite membrane decreased slightly upon recrystallization of the S-layer. Thus, the attached S-layer lattice did not interpenetrate or rupture the DPhPC bilayer. The self-assembly of a pore-forming protein into the S-layer supported lipid bilayer was examined. Staphylococcal alpha-hemolysin formed lytic pores when added to the lipid-exposed side. The assembly was slow compared to unsupported membranes, perhaps due to an altered fluidity of the lipid bilayer. No assembly could be detected upon adding alpha-hemolysin monomers to the S-layer-faced side of the composite membrane. Therefore, the intrinsic molecular sieving properties of the S-layer lattice do not allow passage of alpha-hemolysin monomers through the S-layer pores to the lipid bilayer. In comparison to plain lipid bilayers, the S-layer supported lipid membrane had a decreased tendency to rupture in the presence of alpha-hemolysin.
authors.affiliation: Center for Ultrastructure Research and Ludwig-Boltzmann-Institute for Molecular Nanotechnology, Universität für Bodenkultur Wien, A-1180 Vienna, Austria. bschuste@edv1.boku.ac.at
authors.forename: B
authors.initials: B
authors.lastname: Schuster
authors.forename: D
authors.initials: D
authors.lastname: Pum
authors.forename: O
authors.initials: O
authors.lastname: Braha
authors.forename: H
authors.initials: H
authors.lastname: Bayley
authors.forename: U B
authors.initials: UB
authors.lastname: Sleytr
mesh_terms: D001407:Bacillus / Q000737:chemistry / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001427:Bacterial Toxins / Q000737:chemistry*; D003460:Crystallization; D004553:Electric Conductivity; D006460:Hemolysin Proteins / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism; D008567:Membranes, Artificial; D008854:Microscopy, Electron; D010713:Phosphatidylcholines / Q000737:chemistry; D013210:Staphylococcus / Q000737:chemistry; D013499:Surface Properties
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D008051:Lipid Bilayers; D008562:Membrane Glycoproteins; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; C055764:S-layer proteins; C021091:staphylococcal alpha-toxin; C053686:2,3-di-O-phytanyl-sn-glycero-1-phosphocholine