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PDBsum entry 1d7d
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Oxidoreductase
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PDB id
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1d7d
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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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A new scaffold for binding haem in the cytochrome domain of the extracellular flavocytochrome cellobiose dehydrogenase.
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Authors
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B.M.Hallberg,
T.Bergfors,
K.Bäckbro,
G.Pettersson,
G.Henriksson,
C.Divne.
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Ref.
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Structure, 2000,
8,
79-88.
[DOI no: ]
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PubMed id
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Abstract
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BACKGROUND: The fungal oxidoreductase cellobiose dehydrogenase (CDH) degrades
both lignin and cellulose, and is the only known extracellular flavocytochrome.
This haemoflavoenzyme has a multidomain organisation with a b-type cytochrome
domain linked to a large flavodehydrogenase domain. The two domains can be
separated proteolytically to yield a functional cytochrome and a
flavodehydrogenase. Here, we report the crystal structure of the cytochrome
domain of CDH. RESULTS: The crystal structure of the b-type cytochrome domain of
CDH from the wood-degrading fungus Phanerochaete chrysosporium has been
determined at 1.9 A resolution using multiple isomorphous replacement including
anomalous scattering information. Three models of the cytochrome have been
refined: the in vitro prepared cytochrome in its redox-inactive state (pH 7.5)
and redox-active state (pH 4.6), as well as the naturally occurring cytochrome
fragment. CONCLUSIONS: The 190-residue long cytochrome domain of CDH folds as a
beta sandwich with the topology of the antibody Fab V(H) domain. The haem iron
is ligated by Met65 and His163, which confirms previous results from
spectroscopic studies. This is only the second example of a b-type cytochrome
with this ligation, the first being cytochrome b(562). The haem-propionate
groups are surface exposed and, therefore, might play a role in the association
between the cytochrome and flavoprotein domain, and in interdomain electron
transfer. There are no large differences in overall structure of the cytochrome
at redox-active pH as compared with the inactive form, which excludes the
possibility that pH-dependent redox inactivation results from partial
denaturation. From the electron-density map of the naturally occurring
cytochrome, we conclude that it corresponds to the proteolytically prepared
cytochrome domain.
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Figure 5.
Figure 5. The water-accessible surface of CYT[cdh]. The
surface of the protein molecule is shown in green and the haem
group is in red. The picture was created with INSIGHT II (MSI).
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The above figure is
reprinted
by permission from Cell Press:
Structure
(2000,
8,
79-88)
copyright 2000.
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