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PDBsum entry 1s8l
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Membrane protein
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PDB id
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1s8l
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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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Specificity of anion binding in the substrate pocket of bacteriorhodopsin.
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Authors
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M.T.Facciotti,
V.S.Cheung,
C.S.Lunde,
S.Rouhani,
N.S.Baliga,
R.M.Glaeser.
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Ref.
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Biochemistry, 2004,
43,
4934-4943.
[DOI no: ]
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PubMed id
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Abstract
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The structure of the D85S mutant of bacteriorhodopsin with a nitrate anion bound
in the Schiff base binding site and the structure of the anion-free protein have
been obtained in the same crystal form. Together with the previously solved
structures of this anion pump, in both the anion-free state and bromide-bound
state, these new structures provide insight into how this mutant of
bacteriorhodopsin is able to bind a variety of different anions in the same
binding pocket. The structural analysis reveals that the main structural change
that accommodates different anions is the repositioning of the polar side chain
of S85. On the basis of these X-ray crystal structures, the prediction is then
made that the D85S/D212N double mutant might bind similar anions and do so over
a broader pH range than does the single mutant. Experimental comparison of the
dissociation constants, K(d), for a variety of anions confirms this prediction
and demonstrates, in addition, that the binding affinity is dramatically
improved by the D212N substitution.
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