1j1n

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spinqualitylabelsall models 1j1n, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Structure Analysis of AlgQ2, A Macromolecule(Alginate)-Binding Periplasmic Protein Of Sphingomonas Sp. A1., Complexed with an Alginate Tetrasaccharide

Overview

Sphingomonas sp. A1 possesses a high molecular weight (HMW) alginate, uptake system composed of a novel pit formed on the cell surface and a, pit-dependent ATP-binding cassette (ABC) transporter in the inner, membrane. The transportation of HMW alginate from the pit to the ABC, transporter is mediated by the periplasmic HMW alginate-binding proteins, AlgQ1 and AlgQ2. We determined the crystal structure of AlgQ2 complexed, with an alginate tetrasaccharide using an alginate-free (apo) form as a, search model and refined it at 1.6-A resolution. One tetrasaccharide was, found between the N and C-terminal domains, which are connected by three, extended hinge loops. The tetrasaccharide complex took on a closed domain, form, in contrast to the open domain form of the apo form. The, tetrasaccharide was bound in the cleft between the domains through van der, Waals interactions and the formation of hydrogen bonds. Among the four, sugar residues, the nonreducing end residue was located at the bottom of, the cleft and exhibited the largest number of interactions with the, surrounding amino acid residues, suggesting that AlgQ2 mainly recognizes, and binds to the nonreducing part of a HMW alginate and delivers the, polymer to the ABC transporter through conformational changes (open and, closed forms) of the two domains.

About this Structure

1J1N is a Single protein structure of sequence from Sphingomonas sp. with CA as ligand. Full crystallographic information is available from OCA.

Reference

Crystal structure of AlgQ2, a macromolecule (alginate)-binding protein of Sphingomonas sp. A1, complexed with an alginate tetrasaccharide at 1.6-A resolution., Mishima Y, Momma K, Hashimoto W, Mikami B, Murata K, J Biol Chem. 2003 Feb 21;278(8):6552-9. Epub 2002 Dec 16. PMID:12486124

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