title: Alteration of the langerin oligomerization state affects Birbeck granule formation.
abstract: Langerin, a trimeric C-type lectin specifically expressed in Langerhans cells, has been reported to be a pathogen receptor through the recognition of glycan motifs by its three carbohydrate recognition domains (CRD). In the context of HIV-1 (human immunodeficiency virus-1) transmission, Langerhans cells of genital mucosa play a protective role by internalizing virions in Birbeck Granules (BG) for elimination. Langerin (Lg) is directly involved in virion binding and BG formation through its CRDs. However, nothing is known regarding the mechanism of langerin assembly underlying BG formation. We investigated at the molecular level the impact of two CRD mutations, W264R and F241L, on langerin structure, function, and BG assembly using a combination of biochemical and biophysical approaches. Although the W264R mutation causes CRD global unfolding, the F241L mutation does not affect the overall structure and gp120 (surface HIV-1 glycoprotein of 120 kDa) binding capacities of isolated Lg-CRD. In contrast, this mutation induces major functional and structural alterations of the whole trimeric langerin extracellular domain (Lg-ECD). As demonstrated by small-angle x-ray scattering comparative analysis of wild-type and mutant forms, the F241L mutation perturbs the oligomerization state and the global architecture of Lg-ECD. Correlatively, despite conserved intrinsic lectin activity of the CRD, avidity property of Lg-ECD is affected as shown by a marked decrease of gp120 binding. Beyond the change of residue itself, the F241L mutation induces relocation of the K200 side chain also located within the interface between protomers of trimeric Lg-ECD, thereby explaining the defective oligomerization of mutant Lg. We conclude that not only functional CRDs but also their correct spatial presentation are critical for BG formation as well as gp120 binding.
authors: University Grenoble Alpes, IBS, Grenoble, France; CNRS, UMR 5075, Grenoble France; CEA, UMR 5075, Grenoble France.
authors: Eric
authors: E
authors: Chabrol
authors: University Grenoble Alpes, IBS, Grenoble, France; CNRS, UMR 5075, Grenoble France; CEA, UMR 5075, Grenoble France.
authors: Michel
authors: M
authors: Thépaut
authors: Centre Léon Bérard-UMR INSERM 1052-CNRS 5286, Centre de recherche en Cancérologie de Lyon, Lyon, France.
authors: Colette
authors: C
authors: Dezutter-Dambuyant
authors: University Grenoble Alpes, IBS, Grenoble, France; CNRS, UMR 5075, Grenoble France; CEA, UMR 5075, Grenoble France.
authors: Corinne
authors: C
authors: Vivès
authors: University Grenoble Alpes, IBS, Grenoble, France; CNRS, UMR 5075, Grenoble France; CEA, UMR 5075, Grenoble France.
authors: Julien
authors: J
authors: Marcoux
authors: University Grenoble Alpes, IBS, Grenoble, France; CNRS, UMR 5075, Grenoble France; CEA, UMR 5075, Grenoble France.
authors: Richard
authors: R
authors: Kahn
authors: Centre Léon Bérard-UMR INSERM 1052-CNRS 5286, Centre de recherche en Cancérologie de Lyon, Lyon, France.
authors: Jenny
authors: J
authors: Valladeau-Guilemond
authors: Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Université Paris Sud, Gif sur Yvette, France.
authors: Patrice
authors: P
authors: Vachette
authors: Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Université Paris Sud, Gif sur Yvette, France. Electronic address: dominique.durand@u-psud.fr.
authors: Dominique
authors: D
authors: Durand
authors: University Grenoble Alpes, IBS, Grenoble, France; CNRS, UMR 5075, Grenoble France; CEA, UMR 5075, Grenoble France; Institut Universitaire de France, Paris, France. Electronic address: franck.fieschi@ibs.fr.
authors: Franck
authors: F
authors: Fieschi
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents / Q000494:pharmacology; D018360:Crystallography, X-Ray; D003594:Cytoplasmic Granules / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism / Q000648:ultrastructure; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D006801:Humans; D037181:Lectins, C-Type / Q000737:chemistry* / Q000378:metabolism; D008351:Mannans / Q000378:metabolism; D037241:Mannose-Binding Lectins / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D055503:Protein Multimerization / Q000187:drug effects; D017434:Protein Structure, Tertiary; D053838:Scattering, Small Angle; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014162:Transfection
chemical_list: D015703:Antigens, CD; C121916:CD207 protein, human; D003432:Cross-Linking Reagents; D015699:HIV Envelope Protein gp120; D037181:Lectins, C-Type; D008351:Mannans; D037241:Mannose-Binding Lectins; D050505:Mutant Proteins
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