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Nanoscale Organization of the Pathogen Receptor DC‐SIGN Mapped by Single‐Molecule High‐Resolution Fluorescence Microscopy
Author(s) -
de Bakker Bärbel I.,
de Lange Frank,
Cambi Alessandra,
Korterik Jeroen P.,
van Dijk Erik M. H. P.,
van Hulst Niek F.,
Figdor Carl G.,
GarciaParajo Maria F.
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700169
Subject(s) - near field scanning optical microscope , photobleaching , microscopy , dc sign , fluorescence microscope , resolution (logic) , nanotechnology , super resolution microscopy , optical microscope , materials science , chemistry , biophysics , fluorescence , analytical chemistry (journal) , optics , physics , biology , scanning electron microscope , dendritic cell , chromatography , artificial intelligence , antigen , computer science , composite material , genetics
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.