1hfe
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1.6 A RESOLUTION STRUCTURE OF THE FE-ONLY HYDROGENASE FROM DESULFOVIBRIO DESULFURICANS
OverviewOverview
BACKGROUND: Many microorganisms have the ability to either oxidize, molecular hydrogen to generate reducing power or to produce hydrogen in, order to remove low-potential electrons. These reactions are catalyzed by, two unrelated enzymes: the Ni-Fe hydrogenases and the Fe-only, hydrogenases. RESULTS: We report here the structure of the heterodimeric, Fe-only hydrogenase from Desulfovibrio desulfuricans - the first for this, class of enzymes. With the exception of a ferredoxin-like domain, the, structure represents a novel protein fold. The so-called H cluster of the, enzyme is composed of a typical [4Fe-4S] cubane bridged to a binuclear, active site Fe center containing putative CO and CN ligands and one, bridging 1, 3-propanedithiol molecule. The conformation of the subunits, can be explained by the evolutionary changes that have transformed, monomeric cytoplasmic enzymes into dimeric periplasmic enzymes. Plausible, electron- and proton-transfer pathways and a putative channel for the, access of hydrogen to the active site have been identified. CONCLUSIONS:, The unrelated active sites of Ni-Fe and Fe-only hydrogenases have several, common features: coordination of diatomic ligands to an Fe ion; a vacant, coordination site on one of the metal ions representing a possible, substrate-binding site; a thiolate-bridged binuclear center; and plausible, proton- and electron-transfer pathways and substrate channels. The, diatomic coordination to Fe ions makes them low spin and favors low redox, states, which may be required for catalysis. Complex electron paramagnetic, resonance signals typical of Fe-only hydrogenases arise from magnetic, interactions between the [4Fe-4S] cluster and the active site binuclear, center. The paucity of protein ligands to this center suggests that it was, imported from the inorganic world as an already functional unit.
About this StructureAbout this Structure
1HFE is a Protein complex structure of sequences from Desulfovibrio vulgaris with FE2, CYN, ZN, SF4, PDT, CMO and CYS as ligands. Active as Ferredoxin hydrogenase, with EC number 1.12.7.2 Full crystallographic information is available from OCA.
ReferenceReference
Desulfovibrio desulfuricans iron hydrogenase: the structure shows unusual coordination to an active site Fe binuclear center., Nicolet Y, Piras C, Legrand P, Hatchikian CE, Fontecilla-Camps JC, Structure. 1999 Jan 15;7(1):13-23. PMID:10368269
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