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PDBsum entry 1sor
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Membrane protein
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PDB id
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1sor
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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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Aquaporin-0 membrane junctions reveal the structure of a closed water pore.
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Authors
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T.Gonen,
P.Sliz,
J.Kistler,
Y.Cheng,
T.Walz.
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Ref.
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Nature, 2004,
429,
193-197.
[DOI no: ]
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PubMed id
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Abstract
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The lens-specific water pore aquaporin-0 (AQP0) is the only aquaporin known to
form membrane junctions in vivo. We show here that AQP0 from the lens core,
containing some carboxy-terminally cleaved AQP0, forms double-layered crystals
that recapitulate in vivo junctions. We present the structure of the AQP0
membrane junction as determined by electron crystallography. The junction is
formed by three localized interactions between AQP0 molecules in adjoining
membranes, mainly mediated by proline residues conserved in AQP0s from different
species but not present in most other aquaporins. Whereas all previously
determined aquaporin structures show the pore in an open conformation, the water
pore is closed in AQP0 junctions. The water pathway in AQP0 also contains an
additional pore constriction, not seen in other known aquaporin structures,
which may be responsible for pore gating.
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Figure 2.
Figure 2: The AQP0-mediated membrane junction. a, Ribbon
representation of the membrane junction with the positions of
the two membranes indicated in yellow. b, The Pro 38 residues
contributed by all eight AQP0 subunits in the two interacting
tetramers. c, Corresponding area of the 2F[o] -F[c]map. d, The C
loops connect each AQP0 molecule to two molecules in the
opposite membrane. Letters A to D refer to the molecules
described in the text. e, Corresponding area of the 2F[o] -F[c]
map. Panels a, b and d were created with Chimera^29 and panels c
and e with the program O28.
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Figure 3.
Figure 3: The closed AQP0 water pore. a, b, Side chains
lining the pores in AQP1 (a) and AQP0 (b). c, The left panel
shows pore profiles for AQP0 (red) and AQP1 (green) generated
with the program 'HOLE'. The positions of the NPA motifs, the
ar/R constriction site in AQP1 and the two constriction sites in
AQP0 (CS-I, CS-II) are marked and shown in red. The pore
profiles are aligned with the models of AQP1 (middle panel) and
AQP0 (right panel). Panels a and b were created with Chimera^29.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nature
(2004,
429,
193-197)
copyright 2004.
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