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Figure 3.
(A) Interacting residues in the binding interface. Aromatic
residues from AL-57, which contribute a significant level of
hydrophobic interaction, are shown as stick models with yellow
carbons. E241 from IA and R31(H) from AL-57, which form
electrostatic interactions, are also shown as stick models with
yellow carbons. The metal ion in MIDAS is shown as a purple
sphere. D101(H) from AL-57 is shown as a stick model in yellow.
(B) The movement of the C-terminal α7 helix in IA. The
wild-type LA (PDB code 3F74), unligated IA (PDB code 1MJN), IA
in the AL-57/IA complex, and HA in the ICAM-3/HA (PDB code 1T0P)
complex, were superimposed and colored in gold, cyan, magenta,
and green, respectively. For clarity, only the α1 helices, β6
strands, β6-α7 loops, and α7 helices are shown as Cα traces.
The engineered disulfide bonds (Cys-161-Cys-299 in IA and
Cys-287-Cys-294 in HA) are shown as stick models. Compared to
unligated IA, the β6-α7 loop of IA in AL-57/IA complex moved
downward like that observed in HA, indicating an open
conformation.
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