A high resolution electro-optical approach for investigating transition of soluble proteins to integral membrane proteins probed by colicin A

Autor(en): Honigmann, Alf
Pulagam, Lakshmi Padmavathi
Sippach, Michael
Bartsch, Philipp
Steinhoff, Heinz-Juergen 
Wagner, Richard 
Stichwörter: Artificial bilayer; Biochemistry & Molecular Biology; Biophysics; Colicin A; Colicin A-oligomerization; Electro-optical recording; ESCHERICHIA-COLI; Fluorescence; IA CHANNELS; ION SELECTIVITY; Membran-Protein insertion; Membrane; MODEL; PERMEABILITY; PH; PLANAR LIPID-BILAYERS; PORE-FORMING DOMAIN; TRANSLOCATION; VESICLES
Erscheinungsdatum: 2012
Herausgeber: ACADEMIC PRESS INC ELSEVIER SCIENCE
Journal: BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Volumen: 427
Ausgabe: 2
Startseite: 385
Seitenende: 391
Zusammenfassung: 
The transition from water soluble state to an integral membrane protein state is a crucial step in the formation of the active form of many pore-forming or receptor proteins. Albeit this, high resolution techniques which allow assay of protein membrane binding and concomitant development of the final active form in the membrane await further development. Here, we describe a horizontal artificial bilayers setup allowing for simultaneous electrical and optical measurements at a single molecule level. We use the membrane binding and subsequent channel formation of colicin A (ColA) a water soluble bacteriocin secreted by some strains of Escherichia coli to demonstrate the potential of the combined electro-optical technique. Our results expand the knowledge on ColA molecular details which show that active ColA is monomeric; membrane binding is pH but not membrane-potential (Delta phi) dependent. ColA is at Delta phi=0 permeable for molecules >= 1 nm. Although ColA exhibits low ion conductance it facilitates permeation of large molecules. Our electro-optical recordings reveal ColA monomeric state and the chimeric character of its pore. (C) 2012 Elsevier Inc. All rights reserved.
ISSN: 0006291X
DOI: 10.1016/j.bbrc.2012.09.069

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