title: Contact-mode high-resolution high-speed atomic force microscopy movies of the purple membrane.
abstract: High-speed atomic force microscopy (HS-AFM) is becoming a reference tool for the study of dynamic biological processes. The spatial and time resolutions of HS-AFM are on the order of nanometers and milliseconds, respectively, and allow structural and functional characterization of biological processes at the single-molecule level. In this work we present contact-mode HS-AFM movies of purple membranes containing two-dimensional arrays of bacteriorhodopsin (bR). In high-resolution movies acquired at a 100 ms frame acquisition time, the substructure on individual bR trimers was visualized. In regions in between different bR arrays, dynamic topographies were observed and interpreted as motion of the bR trimers. Similarly, motion of bR monomers in the vicinity of lattice defects in the purple membrane was observed. Our findings indicate that the bR arrays are in a mobile association-dissociation equilibrium. HS-AFM on membranes provides novel perspectives for analyzing the membrane diffusion processes of nonlabeled molecules.
authors.affiliation: Institut Curie, Equipe Institut National de la Sante et de la Recherche Médicale Avenir, Unite Mixte de Recherche 168-Centre National de la Recherche Scientifique, Paris, France.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Casuso
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kodera
authors.forename: Christian
authors.initials: C
authors.lastname: Le Grimellec
authors.forename: Toshio
authors.initials: T
authors.lastname: Ando
authors.forename: Simon
authors.initials: S
authors.lastname: Scheuring
mesh_terms: D001436:Bacteriorhodopsins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D019617:Halobacterium salinarum; D018625:Microscopy, Atomic Force / Q000379:methods*; D009038:Motion; D055503:Protein Multimerization; D018717:Purple Membrane / Q000378:metabolism / Q000648:ultrastructure*; D013997:Time Factors; D014741:Video Recording
chemical_list: D001436:Bacteriorhodopsins