1x0l

Crystal structure of tetrameric homoisocitrate dehydrogenase from an extreme thermophile, Thermus thermophilus

spinqualitylabelsall models 1x0l, resolution 1.85Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1x0l is a 2 chain structure with sequence from "flavobacterium_thermophilum"_yoshida_and_oshima_1971 "flavobacterium thermophilum" yoshida and oshima 1971. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Gene: hicdh ("Flavobacterium thermophilum" Yoshida and Oshima 1971) Activity: Homoisocitrate dehydrogenase, with EC number 1.1.1.87 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 crystal structure of homoisocitrate dehydrogenase involved in lysine biosynthesis from Thermus thermophilus (TtHICDH) was determined at 1.85-A resolution. Arg85, which was shown to be a determinant for substrate specificity in our previous study, is positioned close to the putative substrate binding site and interacts with Glu122. Glu122 is highly conserved in the equivalent position in the primary sequence of ICDH and archaeal 3-isopropylmalate dehydrogenase (IPMDH) but interacts with main- and side-chain atoms in the same domain in those paralogs. In addition, a conserved Tyr residue (Tyr125 in TtHICDH) which extends its side chain toward a substrate and thus has a catalytic function in the related beta-decarboxylating dehydrogenases, is flipped out of the substrate-binding site. These results suggest the possibility that the conformation of the region containing Glu122-Tyr125 is changed upon substrate binding in TtHICDH. The crystal structure of TtHICDH also reveals that the arm region is involved in tetramer formation via hydrophobic interactions and might be responsible for the high thermotolerance. Mutation of Val135, located in the dimer-dimer interface and involved in the hydrophobic interaction, to Met alters the enzyme to a dimer (probably due to steric perturbation) and markedly decreases the thermal inactivation temperature. Both the crystal structure and the mutation analysis indicate that tetramer formation is involved in the extremely high thermotolerance of TtHICDH. Crystal structure of tetrameric homoisocitrate dehydrogenase from an extreme thermophile, Thermus thermophilus: involvement of hydrophobic dimer-dimer interaction in extremely high thermotolerance.,Miyazaki J, Asada K, Fushinobu S, Kuzuyama T, Nishiyama M J Bacteriol. 2005 Oct;187(19):6779-88. PMID:16166541 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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