PDBsum entry 3p7f

Immune system

PDB id: 3p7f

Contents

Protein chain

134 a.a. *

Metals

_CA ×4

Waters ×109

* Residue conservation analysis

PDB id:

3p7f

Name:

Immune system

Title:

Structure of the human langerin carbohydrate recognition domain

Structure:

C-type lectin domain family 4 member k. Chain: a, b, c, d. Fragment: c-terminal domain (unp residues 193-328). Synonym: langerin. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: cd207, clec4k, leucocyte cdna. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.50Å R-factor: 0.189 R-free: 0.243

Authors:

A.Skerra,A.Schiefner

Key ref:

L.Chatwell et al. (2008). The carbohydrate recognition domain of Langerin reveals high structural similarity with the one of DC-SIGN but an additional, calcium-independent sugar-binding site. Mol Immunol, 45, 1981-1994. PubMed id: 18061677 DOI: 10.1016/j.molimm.2007.10.030

Date:

12-Oct-10 Release date: 03-Nov-10

Supersedes:

3bbs

Protein chains

Q9UJ71  (CLC4K_HUMAN) -  C-type lectin domain family 4 member K from Homo sapiens

Seq: 328 a.a.

Struc: 134 a.a.

DOI no: 10.1016/j.molimm.2007.10.030

Mol Immunol 45:1981-1994 (2008)

PubMed id: 18061677

The carbohydrate recognition domain of Langerin reveals high structural similarity with the one of DC-SIGN but an additional, calcium-independent sugar-binding site.

L.Chatwell, A.Holla, B.B.Kaufer, A.Skerra.

ABSTRACT

Langerin is a type II transmembrane oligosaccharide receptor on Langerhans cells (LCs), a prominent subclass of dendritic cells (DCs) that mediate immune responses in epithelia and play a role in HIV degradation. Its extracellular moiety comprises a neck region with several heptad repeats and an exposed carboxy-terminal calcium-type carbohydrate-recognition domain (CRD). The CRD of human Langerin, which was expressed as a soluble protein in the periplasm of E. coli, was crystallized both alone and in the presence of two sugars, followed by X-ray analyses to resolutions of 2.5A for apo-Langerin and to 1.6A and 2.1A for the complexes with mannose and maltose, respectively. The fold of the Langerin CRD (dubbed LangA) resembles that of other typical C-type lectins such as DC-SIGN. However, especially in the long loop region (LLR), which is responsible for carbohydrate-binding, two additional secondary structure elements are present: a 3(10) helix and a small beta-sheet arising from the extended beta-strand 2, which enters into a hairpin and a new strand beta2'. Unexpectedly, the crystal structures in the presence of maltose and mannose reveal two sugar-binding sites. One is calcium-dependent and structurally conserved in the C-type lectin family whereas the second one represents a novel, calcium-independent type. Based on these data, a model for the binding of mannan, a component of many endogenous as well as viral glycoproteins, is proposed and the differences in binding behavior between Langerin and DC-SIGN with respect to the Lewis X carbohydrate antigen and its derivatives can be explained. Therefore, the crystal structure of LangA should be helpful for the development of new marker reagents selective for LCs and also of therapeutic compounds that may enhance the inhibitory role of Langerin towards HIV infection.