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PDBsum entry 1kdg
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Oxidoreductase
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PDB id
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1kdg
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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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Crystal structure of the flavoprotein domain of the extracellular flavocytochrome cellobiose dehydrogenase.
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Authors
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B.M.Hallberg,
G.Henriksson,
G.Pettersson,
C.Divne.
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Ref.
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J Mol Biol, 2002,
315,
421-434.
[DOI no: ]
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PubMed id
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Abstract
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Cellobiose dehydrogenase (CDH) participates in the degradation of cellulose and
lignin. The protein is an extracellular flavocytochrome with a b-type cytochrome
domain (CYT(cdh)) connected to a flavodehydrogenase domain (DH(cdh)). DH(cdh)
catalyses a two-electron oxidation at the anomeric C1 position of cellobiose to
yield cellobiono-1,5-lactone, and the electrons are subsequently transferred
from DH(cdh) to an acceptor, either directly or via CYT(cdh). Here, we describe
the crystal structure of Phanerochaete chrysosporium DH(cdh) determined at 1.5 A
resolution. DH(cdh) belongs to the GMC family of oxidoreductases, which includes
glucose oxidase (GOX) and cholesterol oxidase (COX); however, the sequence
identity with members of the family is low. The overall fold of DH(cdh) is
p-hydroxybenzoate hydroxylase-like and is similar to, but also different from,
that of GOX and COX. It is partitioned into an FAD-binding subdomain of
alpha/beta type and a substrate-binding subdomain consisting of a seven-stranded
beta sheet and six helices. Docking of CYT(cdh) and DH(cdh) suggests that
CYT(cdh) covers the active-site entrance in DH(cdh), and that the resulting
distance between the cofactors is within acceptable limits for inter-domain
electron transfer. Based on docking of the substrate, cellobiose, in the active
site of DH(cdh), we propose that the enzyme discriminates against glucose by
favouring interaction with the non-reducing end of cellobiose.
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Figure 6.
Figure 6. Comparison of the loop-and-lid structure in COX,
GOX and DH[cdh]. (a) COX[Bre] (loop 46-94; lid 95-109), (b)
GOX[Asp] (loop 54-75; lid 76-97), and (c) DH[cdh] (loop 250-288;
lid residues 289-299). The loop and lid segments are coloured
red and blue, respectively. The flavin cofactor is coloured
yellow. The picture was made as described for Figure 1(a).
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Figure 7.
Figure 7. Stereo view of the superimposed active sites in
DH[cdh], GOX and COX. Atom colours: carbon (DH[cdh], yellow;
GOX, pink; COX, green); oxygen, red; nitrogen, blue. Residues
Asn309, His689 and Asn732, as well as the isoalloxazine ring of
the FAD cofactor are shown for DH[cdh]. Superposition was made
to obtain optimal alignment of the pyrimidine moiety and the N5
atom of the flavin ring system. The picture was made as
described for Figure 1(a).
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2002,
315,
421-434)
copyright 2002.
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