1z18

Crystal structure analysis of periplasmic Leu/Ile/Val-binding protein with bound valine

spinqualitylabelsall models 1z18, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1z18 is a 1 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Ligands: CD, VAL Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function LIVJ_ECOLI This protein is a component of the leucine, isoleucine, valine, (threonine) transport system, which is one of the two periplasmic binding protein-dependent transport systems of the high-affinity transport of the branched-chain amino acids. 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 leucine/isoleucine/valine-binding protein (LIVBP or LivJ) serves as the primary high-affinity receptor of the Escherichia coli ABC-type transporter for the three aliphatic amino acids. The first structure of LIVBP determined previously without bound ligand showed a molecule comprised of two domains which are far apart and bisected by a wide open, solvent-accessible cleft. Here we report the crystal structures of another ligand-free state and three complexes with the aliphatic amino acids. In the present ligand-free structure, the two domains are farther apart. In the three very similar complex structures, the two domains are in close proximity, and each desolvated ligand is completely engulfed in the cleft and bound by both domains. The two different ligand-free structures, combined with those of the very similar ligand-bound structures, indicate the trajectory and backbone torsion angle changes of the hinges that accompany domain closure and play crucial functional roles. The amino acids are bound by polar and nonpolar interactions, occurring predominantly in one domain. Consistent with the protein specificity, the aliphatic side chains of the ligands lie in a hydrophobic pocket fully formed following domain or cleft closure. Comparison of the structures of LIVBP with several different binding proteins indicates no correlations between the magnitudes of the hinge-bending angles and the protein masses, the ligand sizes, or the number of segments connecting the two domains. Results of normal-mode analysis and molecular dynamics simulations are consistent with the trajectory and intrinsic flexibility of the interdomain hinges and the dominance of one domain in ligand binding in the open state. Ligand-free and -bound structures of the binding protein (LivJ) of the Escherichia coli ABC leucine/isoleucine/valine transport system: trajectory and dynamics of the interdomain rotation and ligand specificity.,Trakhanov S, Vyas NK, Luecke H, Kristensen DM, Ma J, Quiocho FA Biochemistry. 2005 May 3;44(17):6597-608. PMID:15850393 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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