1fwu
From Proteopedia
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CRYSTAL STRUCTURE OF THE CYSTEINE-RICH DOMAIN OF MANNOSE RECEPTOR COMPLEXED WITH 3-SO4-LEWIS(X)
Overview
The mannose receptor (MR) binds foreign and host ligands through, interactions with their carbohydrates. Two portions of MR have distinct, carbohydrate recognition properties. One is conferred by the, amino-terminal cysteine-rich domain (Cys-MR), which plays a critical role, in binding sulfated glycoproteins including pituitary hormones. The other, is achieved by tandemly arranged C-type lectin domains that facilitate, carbohydrate-dependent uptake of infectious microorganisms. This dual, carbohydrate binding specificity enables MR to bind ligands by interacting, with both sulfated and non-sulfated polysaccharide chains. We previously, determined crystal structures of Cys-MR complexed with, 4-SO(4)-N-acetylglucosamine and with an unidentified ligand resembling, Hepes (N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid]). In, continued efforts to elucidate the mechanism of sulfated carbohydrate, recognition by Cys-MR, we characterized the binding affinities between, Cys-MR and potential carbohydrate ligands using a fluorescence-based, assay. We find that Cys-MR binds sulfated carbohydrates with relatively, high affinities (K(D)=0.1 mM to 1.0 mM) compared to the affinities of, other lectins. Cys-MR also binds Hepes with a K(D) value of 3.9 mM, consistent with the suggestion that the ligand in the original Cys-MR, crystal structure is Hepes. We also determined crystal structures of, Cys-MR complexed with 3-SO(4)-Lewis(x), 3-SO(4)-Lewis(a), and, 6-SO(4)-N-acetylglucosamine at 1.9 A, 2.2 A, and 2.5 A resolution, respectively, and the 2.0 A structure of Cys-MR that had been treated to, remove Hepes. The conformation of the Cys-MR binding site is virtually, identical in all Cys-MR crystal structures, suggesting that Cys-MR does, not undergo conformational changes upon ligand binding. The structures are, used to rationalize the binding affinities derived from the biochemical, studies and to elucidate the molecular mechanism of sulfated carbohydrate, recognition by Cys-MR.
About this Structure
1FWU is a Single protein structure of sequence from Mus musculus. Full crystallographic information is available from OCA.
Reference
The molecular mechanism of sulfated carbohydrate recognition by the cysteine-rich domain of mannose receptor., Liu Y, Misulovin Z, Bjorkman PJ, J Mol Biol. 2001 Jan 19;305(3):481-90. PMID:11152606
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