Structures of the Cd44–hyaluronan complex provide insight into a fundamental carbohydrate-protein interaction

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Regulation of transient interactions between cells and the ubiquitous matrix glycosaminoglycan hyaluronan is crucial to such fundamental processes as embryonic development and leukocyte homing. Cd44, the primary cell surface receptor for hyaluronan, binds ligand via a lectin-like fold termed the Link module, but only after appropriate functional activation. The molecular details of the Cd44-hyaluronan interaction and hence the structural basis for this activation are unknown. Here we present the first crystal structure of Cd44 complexed with hyaluronan. This reveals that the interaction with hyaluronan is dominated by shape and hydrogen-bonding complementarity and identifies two conformational forms of the receptor that differ in orientation of a crucial hyaluronan-binding residue (Arg45, equivalent to Arg41 in human CD44). Measurements by NMR indicate that the conformational transition can be induced by hyaluronan binding, providing further insight into possible mechanisms for regulation of Cd44.

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Figure 1: The HA-binding site in mouse Cd44.
Figure 2: Atomic interactions of HA.
Figure 3: Conformational states of Cd44 involved in HA recognition.

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Protein Data Bank


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Murine Cd44 monoclonal antibodies IRAWB14 and KM81 were obtained from H. Yarwood (Imperial College, London) and J. Lesley (Salk Institute). This work was generously supported by core funding from the UK Medical Research Council (MRC) to the MRC Human Immunology Unit, Oxford (D.G.J.) and the MRC Immunochemistry Unit, Oxford (A.J.D.). A.J.W. received an MRC studentship. A.J.D. and D.J.M. also acknowledge the support of the Arthritis Research Campaign (grant no. 16539).

Author information

Correspondence to Martin Noble or Anthony J Day or David G Jackson.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

Murine CD44/human CD44 structure comparison and sequence alignment (PDF 113 kb)

Supplementary Fig. 2

Calorimetric analysis of CD44-HA interactions (PDF 163 kb)

Supplementary Fig. 3

Structures of free and bound HA8 (PDF 175 kb)

Supplementary Fig. 4

HSQC spectra of wild-type and mutant CD44–HA complexes (PDF 193 kb)

Supplementary Fig. 5

Analysis of HA binding to CD44 HABD mutants (PDF 200 kb)

Supplementary Fig. 6

Perturbations from binding HA6 to CD44 R41A mutant (PDF 202 kb)

Supplementary Table 1

Binding constants for CD44-HA interactions (PDF 38 kb)

Supplementary Video 1

Fly-by movie of CD44-HA interactions (MP4 13716 kb)

Supplementary Video 2 (MP4 1776 kb)

Supplementary Methods

Binding constants for CD44-HA interactions (PDF 110 kb)

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Banerji, S., Wright, A., Noble, M. et al. Structures of the Cd44–hyaluronan complex provide insight into a fundamental carbohydrate-protein interaction. Nat Struct Mol Biol 14, 234–239 (2007) doi:10.1038/nsmb1201

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