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PDBsum entry 4uql
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Oxidoreductase
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PDB id
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4uql
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References listed in PDB file
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Key reference
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Title
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Crystallographic studies of [nife]-Hydrogenase mutants: towards consensus structures for the elusive unready oxidized states.
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Authors
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A.Volbeda,
L.Martin,
E.Barbier,
O.Gutiérrez-Sanz,
A.L.De lacey,
P.P.Liebgott,
S.Dementin,
M.Rousset,
J.C.Fontecilla-Camps.
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Ref.
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J Biol Inorg Chem, 2015,
20,
11-22.
[DOI no: ]
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PubMed id
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Abstract
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Catalytically inactive oxidized O2-sensitive [NiFe]-hydrogenases are
characterized by a mixture of the paramagnetic Ni-A and Ni-B states. Upon O2
exposure, enzymes in a partially reduced state preferentially form the unready
Ni-A state. Because partial O2 reduction should generate a peroxide
intermediate, this species was previously assigned to the elongated Ni-Fe
bridging electron density observed for preparations of [NiFe]-hydrogenases known
to contain the Ni-A state. However, this proposition has been challenged based
on the stability of this state to UV light exposure and the possibility of
generating it anaerobically under either chemical or electrochemical oxidizing
conditions. Consequently, we have considered alternative structures for the Ni-A
species including oxidation of thiolate ligands to either sulfenate or sulfenic
acid. Here, we report both new and revised [NiFe]-hydrogenases structures and
conclude, taking into account corresponding characterizations by Fourier
transform infrared spectroscopy (FTIR), that the Ni-A species contains oxidized
cysteine and bridging hydroxide ligands instead of the peroxide ligand we
proposed earlier. Our analysis was rendered difficult by the typical formation
of mixtures of unready oxidized states that, furthermore, can be reduced by
X-ray induced photoelectrons. The present study could be carried out thanks to
the use of Desulfovibrio fructosovorans [NiFe]-hydrogenase mutants with special
properties. In addition to the Ni-A state, crystallographic results are also
reported for two diamagnetic unready states, allowing the proposal of a revised
oxidized inactive Ni-SU model and a new structure characterized by a persulfide
ion that is assigned to an Ni-'Sox' species.
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Secondary reference #1
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Title
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Structural differences between the ready and unready oxidized states of [nife] hydrogenases.
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Authors
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A.Volbeda,
L.Martin,
C.Cavazza,
M.Matho,
B.W.Faber,
W.Roseboom,
S.P.Albracht,
E.Garcin,
M.Rousset,
J.C.Fontecilla-Camps.
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Ref.
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J Biol Inorg Chem, 2005,
10,
239-249.
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PubMed id
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