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Title
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Fine tuning the specificity of the periplasmic phosphate transport receptor. Site-directed mutagenesis, ligand binding, and crystallographic studies.
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Authors
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Z.Wang,
A.Choudhary,
P.S.Ledvina,
F.A.Quiocho.
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Ref.
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J Biol Chem, 1994,
269,
25091-25094.
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PubMed id
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Abstract
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Phosphorous, primarily in the form of phosphate, is a critical nutrient for the
life of a cell. We have previously determined the 1.7-A resolution structure of
the phosphate-binding protein, an initial receptor for the high-affinity
phosphate active transport system or permease in Escherichia coli (Luecke, H.,
and Quiocho, F.A. (1990) Nature 347, 402-406). This structure is the first to
reveal the key role of hydrogen bonding interactions in conferring the high
specificity of the permease, a specificity also shared by other phosphate
transport systems. Both monobasic and dibasic phosphates are recognized by the
phosphate-binding protein with Asp56 playing a key role. Here we report
site-directed mutagenesis, ligand binding, and crystallographic studies of the
binding protein which show that introduction of one additional Asp by
mutagenesis of the Thr141 in the ligand-binding site restricts binding to only
the monobasic phosphate.
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