Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/82176
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Type: Journal article
Title: Imperfect coordination chemistry facilitates metal ion release in the Psa permease
Author: Counago, R.
Ween, M.
Begg, S.
Bajaj, M.
Zuegg, J.
O'Mara, M.
Cooper, M.
McEwan, A.
Paton, J.
Kobe, B.
McDevitt, C.
Citation: Nature Chemical Biology, 2014; 10(1):35-43
Publisher: Nature Publishing Group
Issue Date: 2014
ISSN: 1552-4450
1552-4469
Statement of
Responsibility: 
Rafael M Couñago, Miranda P Ween, Stephanie L Begg, Megha Bajaj, Johannes Zuegg, Megan L O’Mara, Matthew A Cooper, Alastair G McEwan, James C Paton, Bostjan Kobe, & Christopher A McDevitt
Abstract: The relative stability of divalent first-row transition metal ion complexes, as defined by the Irving-Williams series, poses a fundamental chemical challenge for selectivity in bacterial metal ion acquisition. Here we show that although the substrate-binding protein of Streptococcus pneumoniae, PsaA, is finely attuned to bind its physiological substrate manganese, it can also bind a broad range of other divalent transition metal cations. By combining high-resolution structural data, metal-binding assays and mutational analyses, we show that the inability of open-state PsaA to satisfy the preferred coordination chemistry of manganese enables the protein to undergo the conformational changes required for cargo release to the Psa permease. This is specific for manganese ions, whereas zinc ions remain bound to PsaA. Collectively, these findings suggest a new ligand binding and release mechanism for PsaA and related substrate-binding proteins that facilitate specificity for divalent cations during competition from zinc ions, which are more abundant in biological systems.
Keywords: Streptococcus pneumoniae; Cations; Metals; Membrane Transport Proteins; Binding Sites; Models, Molecular
Rights: © 2014 Nature America, Inc. All rights reserved.
RMID: 0020134403
DOI: 10.1038/NCHEMBIO.1382
Appears in Collections:Molecular and Biomedical Science publications

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