Journal Article

PreJuSER-5165

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Translational Diffusion and Interaction of a Photoreceptor and Its Cognate Transducer Observed in Giant Unilamellar Vesicles by Using Dual-Focus FCS

Kriegsmann, J.FZJ* ; Gregor, I. ; von der Hocht, I. ; Klare, J. ; Engelhard, M. ; Enderlein, J. ; Fitter, J.FZJ*

2009
Wiley-VCH Weinheim

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Please use a persistent id in citations: doi:10.1002/cbic.200900251

Abstract: In order to monitor membrane-protein binding in lipid bilayers at physiological protein concentrations, we employed the recently developed dual-focus fluorescence correlation spectroscopy (2fFCS) technique. In a case study on a photoreceptor consisting of seven transmembrane helices and its cognate transducer (two transmembrane helices), the lateral diffusion for these integral membrane proteins was analyzed in giant unilamellar vesicles (GUVs). The two-dimensional diffusion coefficients of both separately diffusing proteins differ significantly, with D = 2.2 x 10(-8) cm2 s(-1) for the photoreceptor and with D = 4.1 x 10(-8) cm2 s(-1) for the transducer. In GUVs with both membrane proteins present together, we observed significantly smaller diffusion coefficients for labelled transducer molecules; this indicates the presence of larger diffusing units and therefore intermolecular protein binding. Based on the phenomenological dependence of diffusion coefficients on the molecule's cylindrical radius, we are able to estimate the degree of membrane protein binding on a quantitative level.

Keyword(s): Archaeal Proteins: chemistry (MeSH) ; Archaeal Proteins: metabolism (MeSH) ; Carotenoids: chemistry (MeSH) ; Carotenoids: metabolism (MeSH) ; Diffusion (MeSH) ; Lipid Bilayers: chemistry (MeSH) ; Membrane Proteins: chemistry (MeSH) ; Photoreceptors, Microbial: chemistry (MeSH) ; Photoreceptors, Microbial: metabolism (MeSH) ; Protein Binding (MeSH) ; Spectrometry, Fluorescence (MeSH) ; Unilamellar Liposomes: chemistry (MeSH) ; Archaeal Proteins ; HtrII protein, Natronobacterium pharaonis ; Lipid Bilayers ; Membrane Proteins ; Photoreceptors, Microbial ; Unilamellar Liposomes ; phototaxis receptor sensory rhodopsin II, Natronobacterium pharaonis ; Carotenoids ; J ; fluorescence spectroscopy (auto) ; giant unilamellar vesicles (auto) ; membrane proteins (auto) ; photo-signaling complexes (auto) ; protein diffusion (auto)

Note: The priority program SPP 7128 of Deutsche Forschungsgemeinschaft (F1 84113-1,2 to J.F and to J.E) and the DFG graduate school 1035 "Biointerface" are acknowledged for funding. We thank B. Kaupp and G. Baldt for continuous support in their institutes.

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Contributing Institute(s):

1. Molekulare Biophysik (ISB-2)

Research Program(s):

1. Programm Biosoft (N03)

Appears in the scientific report 2009

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