Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/68504
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Type: Journal article
Title: A molecular mechanism for bacterial susceptibility to zinc
Author: McDevitt, C.
Ogunniyi, A.
Valkov, E.
Lawrence, M.
Kobe, B.
McEwan, A.
Paton, J.
Citation: PLoS Pathogens, 2011; 7(11):2357-2365
Publisher: Public Library of Science
Issue Date: 2011
ISSN: 1553-7366
1553-7374
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Responsibility: 
Christopher A. McDevitt, Abiodun D. Ogunniyi, Eugene Valkov, Michael C. Lawrence, Bostjan Kobe, Alastair G. McEwan and James C. Paton
Abstract: Transition row metal ions are both essential and toxic to microorganisms. Zinc in excess has significant toxicity to bacteria, and host release of Zn(II) at mucosal surfaces is an important innate defence mechanism. However, the molecular mechanisms by which Zn(II) affords protection have not been defined. We show that in Streptococcus pneumonia extracellular Zn(II) inhibits the acquisition of the essential metal Mn(II) by competing for binding to the solute binding protein PsaA. We show that, although Mn(II) is the high-affinity substrate for PsaA, Zn(II) can still bind, albeit with a difference in affinity of nearly two orders of magnitude. Despite the difference in metal ion affinities, high-resolution structures of PsaA in complex with Mn(II) or Zn(II) showed almost no difference. However, Zn(II)-PsaA is significantly more thermally stable than Mn(II)-PsaA, suggesting that Zn(II) binding may be irreversible. In vitro growth analyses show that extracellular Zn(II) is able to inhibit Mn(II) intracellular accumulation with little effect on intracellular Zn(II). The phenotype of S. pneumoniae grown at high Zn(II):Mn(II) ratios, i.e. induced Mn(II) starvation, closely mimicked a DpsaA mutant, which is unable to accumulate Mn(II). S. pneumoniae infection in vivo elicits massive elevation of the Zn(II):Mn(II) ratio and, in vitro, these Zn(II):Mn(II) ratios inhibited growth due to Mn(II) starvation, resulting in heightened sensitivity to oxidative stress and polymorphonuclear leucocyte killing. These results demonstrate that microbial susceptibility to Zn(II) toxicity is mediated by extracellular cation competition and that this can be harnessed by the innate immune response.
Keywords: Mucous Membrane; Neutrophils; Animals; Mice; Streptococcus pneumoniae; Pneumococcal Infections; Manganese; Zinc; Lipoproteins; Bacterial Proteins; Adhesins, Bacterial; Bacterial Adhesion; Binding, Competitive; Ion Transport; Protein Binding; Oxidative Stress; Immunity, Innate
Rights: © 2011 McDevitt et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
RMID: 0020114471
DOI: 10.1371/journal.ppat.1002357
Appears in Collections:Molecular and Biomedical Science publications

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