2gpz

Transthyretin-like protein from Salmonella dublin

spinqualitylabelsall models 2gpz, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2gpz is a 2 chain structure with sequence from Saldu. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The mechanism of binding of thyroid hormones by the transport protein transthyretin (TTR) in vertebrates is structurally well characterised. However, a homologous family of transthyretin-like proteins (TLPs) present in bacteria as well as eukaryotes do not bind thyroid hormones, instead they are postulated to perform a role in the purine degradation pathway and function as 5-hydroxyisourate hydrolases. Here we describe the 2.5 Angstroms X-ray crystal structure of the TLP from the Gram-negative bacterium Salmonella dublin, and compare and contrast its structure with vertebrate TTRs. The overall architecture of the homotetramer is conserved and, despite low sequence homology with vertebrate TTRs, structural differences within the monomer are restricted to flexible loop regions. However, sequence variation at the dimer-dimer interface has profound consequences for the ligand binding site and provides a structural rationalisation for the absence of thyroid hormone binding affinity in bacterial TLPs: the deep, negatively charged thyroxine-binding pocket that characterises vertebrate TTR contrasts with a shallow and elongated, positively charged cleft in S. dublin TLP. We have demonstrated that Sdu_TLP is a 5-hydroxyisourate hydrolase. Furthermore, using site-directed mutagenesis, we have identified three conserved residues located in this cleft that are critical to the enzyme activity. Together our data reveal that the active site of Sdu_TLP corresponds to the thyroxine binding site in TTRs. The crystal structure of the transthyretin-like protein from Salmonella dublin, a prokaryote 5-hydroxyisourate hydrolase.,Hennebry SC, Law RH, Richardson SJ, Buckle AM, Whisstock JC J Mol Biol. 2006 Jun 23;359(5):1389-99. Epub 2006 May 11. PMID:16787778 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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