4ucx

Structure of the T18G small subunit mutant of D. fructosovorans NiFe- hydrogenase

spinqualitylabelsall models 4ucx, resolution 1.95Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4ucx is a 6 chain structure with sequence from Solidesulfovibrio fructosivorans. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.95Å Ligands: CSX, FCO, GOL, MG, NI Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PHNS_SOLFR Involved in hydrogen uptake for the anaerobic reduction of sulfate to hydrogen sulfide in an electron transport chain. Cytochrome c3 is the physiological electron acceptor. Publication Abstract from PubMed The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved T18 residue in the small subunit with S, V, Q G or D, and we analysed the effects of these mutations on the kinetic (H2 oxidation, H2 production and H/D exchange), spectroscopic (IR, EPR) and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals, and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of mutants suggests that the alcoholic group of T18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate, and suggests that T18 is essential to stabilize the local protein structure of the active site ensuring fast NiSi-NiC-NiR interconversions during H2 oxidation/production. A Threonine Stabilizes the NiC and NiR Catalytic Intermediates of [NiFe]-hydrogenase.,Abou-Hamdan A, Ceccaldi P, Lebrette H, Guti Eacuterrez-Sanz O, Richaud P, Cournac L, Guigliarelli B, de Lacey AL, L Eacuteger C, Volbeda A, Burlat BE, Dementin SE J Biol Chem. 2015 Feb 9. pii: jbc.M114.630491. PMID:25666617 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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