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PDBsum entry 3bod
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Cell adhesion
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PDB id
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3bod
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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 structures of beta-Neurexin 1 and beta-Neurexin 2 ectodomains and dynamics of splice insertion sequence 4.
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Authors
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J.Koehnke,
X.Jin,
N.Trbovic,
P.S.Katsamba,
J.Brasch,
G.Ahlsen,
P.Scheiffele,
B.Honig,
A.G.Palmer,
L.Shapiro.
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Ref.
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Structure, 2008,
16,
410-421.
[DOI no: ]
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PubMed id
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Abstract
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Presynaptic neurexins (NRXs) bind to postsynaptic neuroligins (NLs) to form
Ca(2+)-dependent complexes that bridge neural synapses. beta-NRXs bind NLs
through their LNS domains, which contain a single site of alternative splicing
(splice site 4) giving rise to two isoforms: +4 and Delta. We present crystal
structures of the Delta isoforms of the LNS domains from beta-NRX1 and
beta-NRX2, crystallized in the presence of Ca(2+) ions. The Ca(2+)-binding site
is disordered in the beta-NRX2 structure, but the 1.7 A beta-NRX1 structure
reveals a single Ca(2+) ion, approximately 12 A from the splice insertion site,
with one coordinating ligand donated by a glutamic acid from an adjacent
beta-NRX1 molecule. NMR studies of beta-NRX1+4 show that the insertion sequence
is unstructured, and remains at least partially disordered in complex with NL.
These results raise the possibility that beta-NRX insertion sequence 4 may
function in roles independent of neuroligin binding.
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Figure 5.
Figure 5. Structure of Δ-Isoform LNS Domains from β-NRX1
and β-NRX2
Rainbow ribbon diagrams from blue to red
representing the N to C terminus. β Strands are numbered, and
the bound Ca^2+ ion in the NRX1 structure is shown as a green
sphere. The α-carbon of residue 200, the position of splice
insertion 4, is shown as a magenta sphere. An eight-residue
stretch in the β9-β10 loop of NRX2 is disordered and is
indicated by a dashed yellow line.
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Figure 6.
Figure 6. Structure of the Ca^2+ Binding Region from β-NRX1,
and Comparison with LNS2 from α-NRX1
(A) Image of 1.7
Å 2F[o]-F[c] electron density contoured at 1.0 σ in the
region of the Ca^2+ binding site.
(B) The Ca^2+ ion is
ligated by four ligands in the Ca^2+ binding site, one water
molecule, and a glutamic acid side chain from a symmetry mate.
(C) Superposition of LNS2 from α-NRX1 (blue) on the
β-NRX1 structure (green and yellow) shows that the Ca^2+
binding sites are positioned identically in each LNS domain.
Ligation by the N208 side chain appears to be common to all the
β-NRX but absent from many other LNS domains of α-NRX.
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The above figures are
reprinted
from an Open Access publication published by Cell Press:
Structure
(2008,
16,
410-421)
copyright 2008.
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