title: Structure and distribution of the Bacillus thuringiensis Cry4Ba toxin in lipid membranes.
abstract: Bacillus thuringiensis Cry delta-endotoxins cause death of susceptible insect larvae by forming lytic pores in the midgut epithelial cell membranes. The 65 kDa trypsin activated Cry4Ba toxin was previously shown to be capable of permeabilizing liposomes and forming ionic channels in receptor-free planar lipid bilayers. Here, magnetic ACmode (MACmode) atomic force microscopy (AFM) was used to characterize the lateral distribution and the native molecular structure of the Cry4Ba toxin in the membrane. Liposome fusion and the Langmuir-Blodgett technique were employed for supported lipid bilayer preparations. The toxin preferentially inserted in a self-assembled structure, rather than as a single monomeric molecule. In addition, the spontaneous insertion into receptor-free lipid bilayers lead to formation of characteristic pore-like structures with four-fold symmetry, suggesting that tetramers are the preferred oligomerization state of this toxin.
authors.affiliation: Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz, Austria.
authors.forename: Theeraporn
authors.initials: T
authors.lastname: Puntheeranurak
authors.forename: Cordula
authors.initials: C
authors.lastname: Stroh
authors.forename: Rong
authors.initials: R
authors.lastname: Zhu
authors.forename: Chanan
authors.initials: C
authors.lastname: Angsuthanasombat
authors.forename: Peter
authors.initials: P
authors.lastname: Hinterdorfer
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism / Q000648:ultrastructure*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism; D004731:Endotoxins / Q000737:chemistry / Q000378:metabolism; D006460:Hemolysin Proteins; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D018625:Microscopy, Atomic Force
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D008051:Lipid Bilayers; C030956:insecticidal crystal protein, Bacillus Thuringiensis