Modelling of auxin-binding protein 1 suggests that its C-terminus and auxin could compete for a binding site that incorporates a metal ion and tryptophan residue 44 |
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Authors: | J Warwicker |
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Institution: | (1) Institute of Biomedical and Life Sciences, Joseph Black Building, Glasgow University, Glasgow G12 8QQ, UK, GB |
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Abstract: | Sequence comparison indicates that auxin-binding protein 1 (ABP1) belongs to a family of proteins with the core β-barrel
structure of the vicilins. Previous modelling within this family correctly predicted metal-ion binding and oligomeric properties
of oxalate oxidase. ABP1 also contains a putative metal-ion-binding cluster of amino acids, adjacent to a tryptophan side
chain, leading to a proposed auxin-binding site that incorporates metal-ion interaction with the auxin carboxylate. Modelling
implicates W44 (Zea mays ABP1) in auxin binding, rather than W136 or W151. Reduced sequence similarity for the C-terminal region prevents model building.
It is proposed that one of these C-terminal tryptophans, along with a neighbouring negatively charged side chain, occupies
the binding pocket in the absence of auxin, thereby linking auxin binding to conformational change and C-terminal involvement
in signalling.
Received: 10 December 1999 / Accepted: 4 August 2000 |
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Keywords: | : Auxin-binding protein 1 Comparative modelling Conformational change Metal-ion binding |
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