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PDBsum entry 2gdc
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Cell invasion
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PDB id
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2gdc
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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 mimicry for vinculin activation by ipaa, A virulence factor of shigella flexneri.
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Authors
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C.Hamiaux,
A.Van eerde,
C.Parsot,
J.Broos,
B.W.Dijkstra.
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Ref.
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EMBO Rep, 2006,
7,
794-799.
[DOI no: ]
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PubMed id
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Abstract
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Invasion of epithelial cells by Shigella flexneri is characterized by
cytoskeletal rearrangements of the host cell membrane, promoting internalization
of the bacterium. The bacterial effector IpaA is injected into the epithelial
cell by a type III secretion apparatus and recruits vinculin to regulate actin
polymerization at the site of entry. We analysed the complex formed between a
carboxy-terminal fragment of IpaA (IpaA(560-633)) and the vinculin D1 domain
(VD1), both in crystals and in solution. We present evidence that IpaA(560-633)
has two alpha-helical vinculin-binding sites that simultaneously bind two VD1
molecules. The interaction of IpaA(560-633) with VD1 is highly similar to the
interaction of the endogenous, eukaryotic proteins talin and alpha-actinin with
VD1, showing that Shigella uses a structural mimicry strategy to activate
vinculin.
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Figure 1.
Figure 1 Crystallographic analysis of IpaA[560–633]/VD1
complex. (A) Overall structure of the IpaA[560-633]/VD1 complex
and portion of the final  [A]-weighted
2F[o]-F[c] electron density map at 1.2 around
the Tyr of IpaA at position 2. IpaA (21 residues corresponding
to either  18
or 20)
is in pink, and VD1 is rainbow-coloured from blue (amino
terminus) to red (carboxyl terminus). For IpaA, the positions of
the residues according to the consensus sequence are indicated.
In the sequence of IpaA[560-633] shown above, 18,
19
and 20
are in red. To the right, the sequence alignment of 18
and 20
is shown, with identical and similar residues in red and blue,
respectively. These two helices are aligned with talin VBS1,
VBS2 and VBS3 and the VBS consensus sequence. (A), (B), (C) and
(D) show the structures of VD1 in complex with IpaA VBS (pink),
talin VBS1 (yellow, PDB entry 1SYQ), VBS2 (red, PDB entry 1UH6)
and VBS3 (orange, PDB entry 1RKC), respectively. All structures
were superimposed using the C atoms
of residues 1–250 of VD1 only, using the VD1/VBS1 structure as
reference. Part (E) (rotated approximately 90° around the
axis of the helix compared with A–D) shows the resulting
(unbiased) superimposition of the four VBSs in a stick mode,
using the same colour code. Conserved positions (1, 5, 8, 12, 16
and 19) of the consensus sequence are labelled, with the
corresponding IpaA residues indicated in parentheses. VD1,
vinculin D1 domain; VBS, vinculin-binding site.
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Figure 3.
Figure 3 Gel filtration profiles of IpaA[560-633]/VD1 mixtures
at different molar ratios, as indicated. Fractions were
collected and analysed by SDS–polyacrylamide gel
electrophoresis. VD1, vinculin D1 domain.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
EMBO Rep
(2006,
7,
794-799)
copyright 2006.
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