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PDBsum entry 2oa5
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Structural protein
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PDB id
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2oa5
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References listed in PDB file
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Key reference
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Title
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Structural and functional studies of the abundant tegument protein orf52 from murine gammaherpesvirus 68.
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Authors
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J.Benach,
L.Wang,
Y.Chen,
C.K.Ho,
S.Lee,
J.Seetharaman,
R.Xiao,
T.B.Acton,
G.T.Montelione,
H.Deng,
R.Sun,
L.Tong.
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Ref.
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J Biol Chem, 2007,
282,
31534-31541.
[DOI no: ]
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PubMed id
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Abstract
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The tegument is a layer of proteins between the nucleocapsid and the envelope of
herpesviruses. The functions of most tegument proteins are still poorly
understood. In murine gammaherpesvirus 68, ORF52 is an abundant tegument protein
of 135 residues that is required for the assembly and release of infectious
virus particles. To help understand the molecular basis for the function of this
protein, we have determined its crystal structure at 2.1 A resolution. The
structure reveals a dimeric association of this protein. Interestingly, an
N-terminal alpha-helix that assumes different conformation in the two monomers
of the dimer mediates the formation of an asymmetrical tetramer and contains
many highly conserved residues. Structural and sequence analyses suggest that
this helix is more likely involved in interactions with other components of the
tegument or nucleocapsid of the virus and that ORF52 functions as a symmetrical
dimer. The asymmetrical tetramer of ORF52 may be a "latent" form of
the protein, when it is not involved in virion assembly. The self-association of
ORF52 has been confirmed by co-immunoprecipitation and fluorescence resonance
energy transfer experiments. Deletion of the N-terminal alpha-helix, as well as
mutation of the conserved Arg(95) residue, abolished the function of ORF52. The
results of the functional studies are fully consistent with the structural
observations and indicate that the N-terminal alpha-helix is a crucial site of
interaction for ORF52.
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Figure 2.
FIGURE 2. Structure of ORF52 dimer. A, schematic drawing of
the ORF52 dimer. Molecule A is shown in gold, and molecule B is
in cyan. B, ORF52 dimer after 90° rotation around the
vertical axis from A. C, a model for the ORF52 dimer with the
 1
helices splayed away from the rest of the molecules. D,
conserved molecular surface features of the dimer model, created
with ConSurf (43). Residues that are conserved among the
herpesviruses are highlighted in blue and labeled. A-C were
created with Pymol (44).
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Figure 3.
FIGURE 3. An asymmetric tetramer of ORF52. A, schematic
drawing of the ORF52 tetramer. One dimer is shown in gold and
cyan, and other is in green and magenta. B, ORF52 tetramer after
180° rotation around the vertical axis from A. C, molecular
surface of the ORF52 tetramer, in the same view as A, colored by
electrostatic potentials. D, molecular surface of the ORF52
tetramer in the same view as B. E, conserved molecular surface
features of the ORF52 tetramer. A, B, and E created with Pymol
(44), and C and D were created with Grasp (45).
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2007,
282,
31534-31541)
copyright 2007.
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