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PDBsum entry 1hfe
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Desulfovibrio desulfuricans iron hydrogenase: the structure shows unusual coordination to an active site fe binuclear center.
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Authors
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Y.Nicolet,
C.Piras,
P.Legrand,
C.E.Hatchikian,
J.C.Fontecilla-Camps.
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Ref.
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Structure, 1999,
7,
13-23.
[DOI no: ]
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PubMed id
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Abstract
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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
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
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.
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Figure 6.
Figure 6. Interactions of the binuclear Fe center with the
protein. Besides the bridging Cys382 residue, two of the
putative ligands form hydrogen bonds (dashed lines) with the
protein (see text for details). (The figure was prepared using
the program TURBO-FRODO [39].)
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The above figure is
reprinted
by permission from Cell Press:
Structure
(1999,
7,
13-23)
copyright 1999.
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