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PDBsum entry 1xhh
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Unknown function
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PDB id
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1xhh
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References listed in PDB file
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Key reference
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Title
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Novel solution structure of porcine beta-Microseminoprotein.
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Authors
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I.Wang,
Y.C.Lou,
K.P.Wu,
S.H.Wu,
W.C.Chang,
C.Chen.
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Ref.
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J Mol Biol, 2005,
346,
1071-1082.
[DOI no: ]
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PubMed id
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Abstract
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A number of beta-microseminoproteins (MSPs) have been identified from different
species. MSPs are all non-glycosylated and disulfide bond-rich, but show a
relatively low level of conservation. Although all Cys residues are conserved,
our previous study showed that the disulfide bond pairings differ in porcine and
ostrich MSPs. Despite the variety of biological functions that have been
suggested for MSPs, their real function is still poorly understood. Furthermore,
no 3D structure has been reported for any MSP, so the determination of the
structure and function of MSPs is an interesting and important task. In the
present study, we determined the 3D solution structure of porcine MSP on the
basis of 1018 restraints. The ensemble of 20 NMR structures was well defined,
with average root-mean-square deviations of 0.83(+/-0.16) A for the backbone
atoms and 1.37(+/-0.17) A for heavy-atoms in residues 2-90. The 3D structure
showed that porcine MSP is clearly composed of two domains, an N-terminal domain
consisting of one double-stranded and one four-stranded antiparallel beta-sheet,
and a C-terminal domain consisting of two double-stranded antiparallel
beta-sheet. The orientation of the two domains was derived mainly on the basis
of long-range NOEs and verified using residual dipolar coupling data. No
inter-domain hydrophobic interaction or H-bonding was detected. However, a
number of charged residues were found in close proximity between the domains,
indicating that electrostatic interaction may be the key factor for the
orientation of the two domains. This is the first report of a 3D structure for
any MSP. In addition, structural comparison based on distance matrix alignment
(DALI), class architecture topology and homologous superfamily (CATH) and
combinatorial extension (CE) methods revealed that porcine MSP has a novel
structure with a new fold providing valuable information for future structural
studies on other MSPs and for understanding their biological functions.
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Figure 5.
Figure 5. Surface structure of porcine MSP displayed as a
180° rotation with positive and negative charges shown in
blue and red, respectively.
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Figure 8.
Figure 8. Comparison of the 3D structures of porcine MSP
and a fibronectin fragment (PDB number 1E8B). Similar regions in
the two structures are shown in red and the ranges of each
region used for comparison are labeled using different color
codes.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2005,
346,
1071-1082)
copyright 2005.
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