Nanoscale organization of the pathogen receptor DC-SIGN mapped by single-molecule high-resolution flourescence microscopy

B.I. de Bakker, Frank de Lange, Alessandra Cambi, A. Cambi, Jeroen P. Korterik, E.M.H.P. van Dijk, N.F. van Hulst, Carl Figdor, M.F. Garcia Parajo

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Abstract

DC-SIGN, a C-type lectin exclusively expressed on dendritic cells (DCs), plays an important role in pathogen recognition by binding with high affinity to a large variety of microorganisms. Recent experimental evidence points to a direct relation between the function of DC-SIGN as a viral receptor and its spatial arrangement on the plasma membrane. We have investigated the nanoscale organization of fluorescently labeled DC-SIGN on intact isolated DCs by means of near-field scanning optical microscopy (NSOM) combined with single-molecule detection. Fluorescence spots of different intensity and size have been directly visualized by optical means with a spatial resolution of less than 100 nm. Intensity- and size-distribution histograms of the DC-SIGN fluorescent spots confirm that approximately 80 % of the receptors are organized in nanosized domains randomly distributed on the cell membrane. Intensity-size correlation analysis revealed remarkable heterogeneity in the molecular packing density of the domains. Furthermore, we have mapped the intermolecular organization within a dense cluster by means of sequential NSOM imaging combined with discrete single-molecule photobleaching. In this way we have determined the spatial coordinates of 13 different individual dyes, with a localization accuracy of 6 nm. Our experimental observations are all consistent with an arrangement of DC-SIGN designed to maximize its chances of binding to a wide range of microorganisms. Our data also illustrate the potential of NSOM as an ultrasensitive, high-resolution technique to probe nanometer-scale organization of molecules on the cell membrane.
Original languageUndefined
Pages (from-to)1473-1480
Number of pages8
JournalChemPhysChem
Volume8
Issue number10
DOIs
Publication statusPublished - 2007

Keywords

  • IR-61521
  • METIS-241213

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