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Severe zinc depletion of escherichia coli: roles for high affinity zinc binding by ZinT, zinc transport and zinc-independent proteins

Graham, A.I., Hunt, S., Stokes, S.L., Bramall, N., Bunch, J., Cox, A.G., McLeod, C.W. and Poole, R.K. (2009) Severe zinc depletion of escherichia coli: roles for high affinity zinc binding by ZinT, zinc transport and zinc-independent proteins. Journal of Biological Chemistry, 284 (27). pp. 18377-18389. ISSN 0021-9258

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Zinc ions play indispensable roles in biological chemistry. However, bacteria have an impressive ability to acquire Zn2+ from the environment, making it exceptionally difficult to achieve Zn2+ deficiency, and so a comprehensive understanding of the importance of Zn2+ has not been attained. Reduction of the Zn2+ content of Escherichia coli growth medium to 60 nM or less is reported here for the first time, without recourse to chelators of poor specificity. Cells grown in Zn2+-deficient medium had a reduced growth rate and contained up to five times less cellular Zn2+. To understand global responses to Zn2+ deficiency, microarray analysis was conducted of cells grown under Zn2+-replete and Zn2+-depleted conditions in chemostat cultures. Nine genes were up-regulated more than 2-fold (p<0.05) in cells from Zn2+-deficient chemostats, including zinT (yodA). zinT is shown to be regulated by Zur ( zinc uptake regulator). A mutant lacking zinT displayed a growth defect and a 3-fold lowered cellular Zn2+ level under Zn2+ limitation. The purified ZinT protein possessed a single, high affinity metal-binding site that can accommodate Zn2+ or Cd2+. A further up-regulated gene, ykgM, is believed to encode a non-Zn2+ finger-containing paralogue of the Zn2+ finger ribosomal protein L31. The gene encoding the periplasmic Zn2+- binding protein znuA showed increased expression. During both batch and chemostat growth, cells "found" more Zn2+ than was originally added to the culture, presumably because of leaching from the culture vessel. Zn2+ elimination is shown to be a more precise method of depleting Zn2+ than by using the chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine.

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 American Society for Biochemistry and Molecular Biology. This is an author produced version of a paper subsequently published in Journal of Biological Chemistry. Uploaded in accordance with the publisher's self-archiving policy.
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Biological Sciences (Sheffield) > Department of Molecular Biology and Biotechnology (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 03 Aug 2009 14:16
Last Modified: 09 Jun 2014 23:04
Published Version: http://dx.doi.org/10.1074/jbc.M109.001503
Status: Published
Publisher: American Society for Biochemistry and Molecular Biology
Refereed: Yes
Identification Number: 10.1074/jbc.M109.001503
URI: http://eprints.whiterose.ac.uk/id/eprint/9031

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