1jt9

Structure of the mutant F174A T form of the Glucosamine-6-Phosphate deaminase from E.coli

spinqualitylabelsall models 1jt9, resolution 2.06Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1jt9 is a 1 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.06Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NAGB_ECOLI Catalyzes the reversible isomerization-deamination of glucosamine 6-phosphate (GlcN6P) to form fructose 6-phosphate (Fru6P) and ammonium ion.[HAMAP-Rule:MF_01241] 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 active site of glucosamine-6-phosphate deaminase from Escherichia coli (GlcN6P deaminase, EC 3.5.99.6) has a complex lid formed by two antiparallel beta-strands connected by a helix-loop segment (158-187). This motif contains Arg172, which is a residue involved in binding the substrate in the active-site, and three residues that are part of the allosteric site, Arg158, Lys160 and Thr161. This dual binding role of the motif forming the lid suggests that it plays a key role in the functional coupling between active and allosteric sites. Previous crystallographic work showed that the temperature coefficients of the active-site lid are very large when the enzyme is in its T allosteric state. These coefficients decrease in the R state, thus suggesting that this motif changes its conformational flexibility as a consequence of the allosteric transition. In order to explore the possible connection between the conformational flexibility of the lid and the function of the deaminase, we constructed the site-directed mutant Phe174-Ala. Phe174 is located at the C-end of the lid helix and its side-chain establishes hydrophobic interactions with the remainder of the enzyme. The crystallographic structure of the T state of Phe174-Ala deaminase, determined at 2.02 A resolution, shows no density for the segment 162-181, which is part of the active-site lid (PDB 1JT9). This mutant form of the enzyme is essentially inactive in the absence of the allosteric activator, N-acetylglucosamine-6-P although it recovers its activity up to the wild-type level in the presence of this ligand. Spectrometric and binding studies show that inactivity is due to the inability of the active-site to bind ligands when the allosteric site is empty. These data indicate that the conformational flexibility of the active-site lid critically alters the binding properties of the active site, and that the occupation of the allosteric site restores the lid conformational flexibility to a functional state. On the role of the conformational flexibility of the active-site lid on the allosteric kinetics of glucosamine-6-phosphate deaminase.,Bustos-Jaimes I, Sosa-Peinado A, Rudino-Pinera E, Horjales E, Calcagno ML J Mol Biol. 2002 May 24;319(1):183-9. PMID:12051945 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Deaminase 3D structures

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