HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Lewin, A. C. Articles by Spiro, S. Search for Related Content PubMed PubMed Citation Articles by Lewin, A. C. Articles by Spiro, S. Agricola Articles by Lewin, A. C. Articles by Spiro, S.

The ferric uptake regulator of Pseudomonas aeruginosa has no essential cysteine residues and does not contain a structural zinc ion

School of Biological Sciences¹ and School of Chemical Sciences², University of East Anglia, Norwich NR4 7TJ, UK

Author for correspondence: Stephen Spiro. Tel: +44 1603 593222. Fax: +44 1603 592250. e-mail: s.spiro{at}uea.ac.uk

The ferric uptake regulator (Fur) of Pseudomonas aeruginosa was expressed in Escherichia coli in its native form and as a fusion to the maltose-binding protein (MBP). Fur from the MBP fusion bound to MBP after proteolytic cleavage, and the two could only be separated by partial unfolding. The refolded protein was in the same conformation as native protein (as judged by circular dichroism and fluorescence spectroscopies) and was fully active in DNA-binding assays. As-prepared native Fur contained small amounts of Zn²⁺ that were easily removed by treatment with EDTA, and apo-protein could be reconstituted with approximately one Zn²⁺ ion per monomer. Thus, the P. aeruginosa Fur can probably accommodate a single Zn²⁺ ion bound to the metal-sensing site. The single cysteine residue of P. aeruginosa Fur aligns with a cysteine in other members of the Fur family that is essential for activity of the E. coli protein, and is believed to provide one of the ligands to a structural Zn²⁺ ion. This cysteine residue was shown to be dispensable for the in vivo activity of P. aeruginosa Fur, which is consistent with the suggestion that the P. aeruginosa protein does not contain a structural Zn²⁺ ion. Members of the Fur family contain a highly conserved His-His-Asp-His motif. Alanine substitutions of residues in this motif showed His-87 and His-89 of P. aeruginosa Fur to be essential for activity, whilst His-86 and Asp-88 are partially dispensable.

Keywords: Fur, iron regulation

Abbreviations: CD, circular dichroism; Gdn . HCl, guanidinium hydrochloride; MBP, maltose-binding protein

^a Present address: School of Biological Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.

This article has been cited by other articles:

				N. Ledala, S. L. Pearson, B. J. Wilkinson, and R. K. Jayaswal Molecular characterization of the Fur protein of Listeria monocytogenes Microbiology, April 1, 2007; 153(4): 1103 - 1111. [Abstract] [Full Text] [PDF]

				L. Pecqueur, B. D'Autreaux, J. Dupuy, Y. Nicolet, L. Jacquamet, B. Brutscher, I. Michaud-Soret, and B. Bersch Structural Changes of Escherichia coli Ferric Uptake Regulator during Metal-dependent Dimerization and Activation Explored by NMR and X-ray Crystallography J. Biol. Chem., July 28, 2006; 281(30): 21286 - 21295. [Abstract] [Full Text] [PDF]

				Y. E. Friedman and M. R. O'Brian The Ferric Uptake Regulator (Fur) Protein from Bradyrhizobium japonicum Is an Iron-responsive Transcriptional Repressor in Vitro J. Biol. Chem., July 30, 2004; 279(31): 32100 - 32105. [Abstract] [Full Text] [PDF]