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PDBsum entry 1qu1
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Viral protein
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PDB id
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1qu1
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Contents |
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133 a.a.
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144 a.a.
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155 a.a.
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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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N- And c-Terminal residues combine in the fusion-Ph influenza hemagglutinin ha(2) subunit to form an n cap that terminates the triple-Stranded coiled coil.
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Authors
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J.Chen,
J.J.Skehel,
D.C.Wiley.
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Ref.
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Proc Natl Acad Sci U S A, 1999,
96,
8967-8972.
[DOI no: ]
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PubMed id
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Abstract
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The structure of a stable recombinant ectodomain of influenza hemagglutinin
HA(2) subunit, EHA(2) (23-185), defined by proteolysis studies of the intact
bacterial-expressed ectodomain, was determined to 1.9-A resolution by using
x-ray crystallography. The structure reveals a domain composed of N- and
C-terminal residues that form an N cap terminating both the N-terminal
alpha-helix and the central coiled coil. The N cap is formed by a conserved
sequence, and part of it is found in the neutral pH conformation of HA. The
C-terminal 23 residues of the ectodomain form a 72-A long nonhelical structure
ordered to within 7 residues of the transmembrane anchor. The structure implies
that continuous alpha helices are not required for membrane fusion at either the
N or C termini. The difference in stability between recombinant molecules with
and without the N cap sequences suggests that additional free energy for
membrane fusion may become available after the formation of the central
triple-stranded coiled coil and insertion of the fusion peptide into the target
membrane.
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Figure 4.
Fig. 4. N cap domain of EHA[2](23-185). (A) Stereo ribbon
diagram of the N-terminal residues (dark blue, dark red, dark
yellow) and the C-terminal residues (light colors) of EHA[2]
(23-185), viewed down the molecular threefold-symmetry axis. (B)
Stereoatomic diagram of the N-terminal residues (colors and view
as in A) and the C-terminal residues of EHA[2] (23-185).
Potential hydrogen bonds are green dashed lines. (C)
Stereoribbon diagram as in A but viewed perpendicular to the
molecular threefold-symmetry axis. (D) Stereoatomic diagram as
in B but viewed as in C. Figure prepared with RIBBONS (43).
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Figure 5.
Fig. 5. Comparison of TBHA[2] from low pH-treated HA and
EBHA[2](23-185). (A) TBHA[2] (residues 1-27 of HA[1] and 38-175
of HA[2]) from thermolytic digestion of low pH-treated viral
BHA. The white molecular surface is the central triple-stranded
coiled coil. The atomic models are the C-terminal residues
beyond residue 106 colored differently for each monomer. The
last residues visible in the electron density at the termini are
labeled. (B) EBHA[2] (23-185) with the N-terminal residues from
34 to 40 colored yellow. The rendering is as in A with the
visible terminal residues labeled. Figure prepared with GRASP
(44).
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