1cc1 | pdb_00001cc1

CRYSTAL STRUCTURE OF A REDUCED, ACTIVE FORM OF THE NI-FE-SE HYDROGENASE FROM DESULFOMICROBIUM BACULATUM

spinqualitylabelsall models 1cc1, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1cc1 is a 2 chain structure with sequence from Desulfomicrobium baculatum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.15Å Ligands: FCO, FE2, H2S, NI Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PHSS_DESBA 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 BACKGROUND: [NiFeSe] hydrogenases are metalloenzymes that catalyze the reaction H2<-->2H+ + 2e-. They are generally heterodimeric, contain three iron-sulfur clusters in their small subunit and a nickel-iron-containing active site in their large subunit that includes a selenocysteine (SeCys) ligand. RESULTS: We report here the X-ray structure at 2.15 A resolution of the periplasmic [NiFeSe] hydrogenase from Desulfomicrobium baculatum in its reduced, active form. A comparison of active sites of the oxidized, as-prepared, Desulfovibrio gigas and the reduced D. baculatum hydrogenases shows that in the reduced enzyme the nickel-iron distance is 0.4 A shorter than in the oxidized enzyme. In addition, the putative oxo ligand, detected in the as-prepared D. gigas enzyme, is absent from the D. baculatum hydrogenase. We also observe higher-than-average temperature factors for both the active site nickel-selenocysteine ligand and the neighboring Glu18 residue, suggesting that both these moieties are involved in proton transfer between the active site and the molecular surface. Other differences between [NiFeSe] and [NiFe] hydrogenases are the presence of a third [4Fe4S] cluster replacing the [3Fe4S] cluster found in the D. gigas enzyme, and a putative iron center that substitutes the magnesium ion that has already been described at the C terminus of the large subunit of two [NiFe] hydrogenases. CONCLUSIONS: The heterolytic cleavage of molecular hydrogen seems to be mediated by the nickel center and the selenocysteine residue. Beside modifying the catalytic properties of the enzyme, the selenium ligand might protect the nickel atom from oxidation. We conclude that the putative oxo ligand is a signature of inactive 'unready' [NiFe] hydrogenases. The crystal structure of a reduced [NiFeSe] hydrogenase provides an image of the activated catalytic center.,Garcin E, Vernede X, Hatchikian EC, Volbeda A, Frey M, Fontecilla-Camps JC Structure. 1999 May;7(5):557-66. PMID:10378275 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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