3use | pdb_00003use

Crystal Structure of E. coli hydrogenase-1 in its as-isolated form

spinqualitylabelsall models 3use, resolution 1.67Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3use is a 4 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 1.67Å Ligands: 3NI, CL, FCO, GOL, LI, LMT, MG, SF3, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MBHS_ECOLI This is one of three E.coli hydrogenases synthesized in response to different physiological conditions. HYD1 is believed to have a role in hydrogen cycling during fermentative growth. Publication Abstract from PubMed The crystal structure of the membrane-bound O(2)-tolerant [NiFe]-hydrogenase 1 from Escherichia coli (EcHyd-1) has been solved in three different states: as-isolated, H(2)-reduced, and chemically oxidized. As very recently reported for similar enzymes from Ralstonia eutropha and Hydrogenovibrio marinus, two supernumerary Cys residues coordinate the proximal [FeS] cluster in EcHyd-1, which lacks one of the inorganic sulfide ligands. We find that the as-isolated, aerobically purified species contains a mixture of at least two conformations for one of the cluster iron ions and Glu76. In one of them, Glu76 and the iron occupy positions that are similar to those found in O(2)-sensitive [NiFe]-hydrogenases. In the other conformation, this iron binds, besides three sulfur ligands, the amide N from Cys20 and one Oepsilon of Glu76. Our calculations show that oxidation of this unique iron generates the high-potential form of the proximal cluster. The structural rearrangement caused by oxidation is confirmed by our H(2)-reduced and oxidized EcHyd-1 structures. Thus, thanks to the peculiar coordination of the unique iron, the proximal cluster can contribute two successive electrons to secure complete reduction of O(2) to H(2)O at the active site. The two observed conformations of Glu76 are consistent with this residue playing the role of a base to deprotonate the amide moiety of Cys20 upon iron binding and transfer the resulting proton away, thus allowing the second oxidation to be electroneutral. The comparison of our structures also shows the existence of a dynamic chain of water molecules, resulting from O(2) reduction, located near the active site. X-ray crystallographic and computational studies of the O2-tolerant [NiFe]-hydrogenase 1 from Escherichia coli.,Volbeda A, Amara P, Darnault C, Mouesca JM, Parkin A, Roessler MM, Armstrong FA, Fontecilla-Camps JC Proc Natl Acad Sci U S A. 2012 Apr 3;109(14):5305-10. Epub 2012 Mar 19. PMID:22431599 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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