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Figure 3.
Fig. 3. Diagram of the MIDAS motif in  A (A and B)
and  A from
CD11b (C and D). (A) and (B) MIDAS residues (single letter
abbreviations: S, Ser; E, Glu; D, Asp; T, Thr) in unliganded (A)
and liganded (B) A.
Coordinating side chains are shown in ball-and-stick
representations with oxygen atoms in red, carbon in green; the
ligand aspartate is in gold. In addition to the ligand
aspartate, the Mn2+ (cyan) in the A MIDAS is
coordinated directly with the hydroxyl oxygens of Ser121 and
Ser123 and with one carboxylate oxygen from Glu220. The carboxyl
oxygens of Asp119 and Asp251 of A lie
within 6Å of the metal ion and likely mediate additional
contacts through water molecules similar to the liganded forms
of A (D). The
Mn2+ ion at ADMIDAS (magenta) is present in (A) and (B). The
Mn2+ ions at MIDAS and at LIMBS (cyan and gray, respectively)
are only present in (B). (C) and (D) MIDAS residues in
unliganded (C) and liganded (D) A from
CD11b. The metal ion (cyan) is present in both. Water molecules
are labeled  ; the
pseudoligand glutamate is in gold. Hydrogen bonds and metal ion
coordination are represented with dotted yellow lines.
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