title: Binding Sites for Acylated Trehalose Analogs of Glycolipid Ligands on an Extended Carbohydrate Recognition Domain of the Macrophage Receptor Mincle.
abstract: The macrophage receptor mincle binds to trehalose dimycolate on the surface of Mycobacterium tuberculosis Signaling initiated by this interaction leads to cytokine production, which underlies the ability of mycobacteria to evade the immune system and also to function as adjuvants. In previous work the mechanism for binding of the sugar headgroup of trehalose dimycolate to mincle has been elucidated, but the basis for enhanced binding to glycolipid ligands, in which hydrophobic substituents are attached to the 6-hydroxyl groups, has been the subject of speculation. In the work reported here, the interaction of trehalose derivatives with bovine mincle has been probed with a series of synthetic mimics of trehalose dimycolate in binding assays, in structural studies by x-ray crystallography, and by site-directed mutagenesis. Binding studies reveal that, rather than reflecting specific structural preference, the apparent affinity of mincle for ligands with hydrophobic substituents correlates with their overall size. Structural and mutagenesis analysis provides evidence for interaction of the hydrophobic substituents with multiple different portions of the surface of mincle and confirms the presence of three Ca2+-binding sites. The structure of an extended portion of the extracellular domain of mincle, beyond the minimal C-type carbohydrate recognition domain, also constrains the way the binding domains may interact on the surface of macrophages.
authors.affiliation: From the Departments of Structural Biology and Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305.
authors.forename: Hadar
authors.initials: H
authors.lastname: Feinberg
authors.affiliation: the Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom, and.
authors.forename: Neela D S
authors.initials: ND
authors.lastname: Rambaruth
authors.affiliation: the Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom, and.
authors.forename: Sabine A F
authors.initials: SA
authors.lastname: Jégouzo
authors.affiliation: Chemical Biology Laboratory, Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark.
authors.forename: Kristian M
authors.initials: KM
authors.lastname: Jacobsen
authors.affiliation: Chemical Biology Laboratory, Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark.
authors.forename: Rasmus
authors.initials: R
authors.lastname: Djurhuus
authors.affiliation: Chemical Biology Laboratory, Department of Chemistry, Aarhus University, DK-8000 Aarhus, Denmark.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Poulsen
authors.affiliation: From the Departments of Structural Biology and Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305.
authors.forename: William I
authors.initials: WI
authors.lastname: Weis
authors.affiliation: the Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom, and.
authors.forename: Maureen E
authors.initials: ME
authors.lastname: Taylor
authors.affiliation: the Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom, and k.drickamer@imperial.ac.uk.
authors.forename: Kurt
authors.initials: K
authors.lastname: Drickamer
mesh_terms: D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002417:Cattle; D018360:Crystallography, X-Ray; D057927:Hydrophobic and Hydrophilic Interactions; D037181:Lectins, C-Type / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D013329:Structure-Activity Relationship; D014199:Trehalose / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism
chemical_list: D037181:Lectins, C-Type; D014199:Trehalose; D002118:Calcium
keywords: carbohydrate-binding protein; glycolipid; lectin; mycobacteria; tuberculosis