1uxj

Large improvement in the thermal stability of a tetrameric malate dehydrogenase by single point mutations at the dimer-dimer interface

spinqualitylabelsall models 1uxj, resolution 1.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1uxj is a 2 chain structure with sequence from Chloroflexus aurantiacus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.75Å Ligands: CD, CL, NA, NAD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MDH_CHLAA Catalyzes the reversible oxidation of malate to oxaloacetate.[HAMAP-Rule:MF_00487] 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 stability of tetrameric malate dehydrogenase from the green phototrophic bacterium Chloroflexus aurantiacus (CaMDH) is at least in part determined by electrostatic interactions at the dimer-dimer interface. Since previous studies had indicated that the thermal stability of CaMDH becomes lower with increasing pH, attempts were made to increase the stability by removal of (excess) negative charge at the dimer-dimer interface. Mutation of Glu165 to Gln or Lys yielded a dramatic increase in thermal stability at pH 7.5 (+23.6 -- + 23.9 degrees C increase in apparent t(m)) and a more moderate increase at pH 4.4 (+4.6 -- + 5.4 degrees C). The drastically increased stability at neutral pH was achieved without forfeiture of catalytic performance at low temperatures. The crystal structures of the two mutants showed only minor structural changes close to the mutated residues, and indicated that the observed stability effects are solely due to subtle changes in the complex network of electrostatic interactions in the dimer-dimer interface. Both mutations reduced the concentration dependency of thermal stability, suggesting that the oligomeric structure had been reinforced. Interestingly, the two mutations had similar effects on stability, despite the charge difference between the introduced side-chains. Together with the loss of concentration dependency, this may indicate that both E165Q and E165K stabilize CaMDH to such an extent that disruption of the inter-dimer electrostatic network around residue 165 no longer limits kinetic thermal stability. Large improvement in the thermal stability of a tetrameric malate dehydrogenase by single point mutations at the dimer-dimer interface.,Bjork A, Dalhus B, Mantzilas D, Sirevag R, Eijsink VG J Mol Biol. 2004 Aug 27;341(5):1215-26. PMID:15321717 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Malate Dehydrogenase 3D structures

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