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 Blank, L. Articles by Guest, J. R. Search for Related Content PubMed PubMed Citation Articles by Blank, L. Articles by Guest, J. R. Agricola Articles by Blank, L. Articles by Guest, J. R.

AcnC of Escherichia coli is a 2-methylcitrate dehydratase (PrpD) that can use citrate and isocitrate as substrates

The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK¹

Author for correspondence: John R. Guest. Tel: +44 114 2224406. Fax: +44 114 2728697. e-mail: j.r.guest{at}sheffield.ac.uk

Escherichia coli possesses two well-characterized aconitases (AcnA and AcnB) and a minor activity (designated AcnC) that is retained by acnAB double mutants and represents no more than 5% of total wild-type aconitase activity. Here it is shown that a 2-methylcitrate dehydratase (PrpD) encoded by the prpD gene of the propionate catabolic operon (prpRBCDE) is identical to AcnC. Inactivation of prpD abolished the residual aconitase activity of an AcnAB-null strain, whereas inactivation of ybhJ, an unidentified acnA paralogue, had no significant effect on AcnC activity. Purified PrpD catalysed the dehydration of citrate and isocitrate but was most active with 2-methylcitrate. PrpD also catalysed the dehydration of several other hydroxy acids but failed to hydrate cis-aconitate and related substrates containing double bonds, indicating that PrpD is not a typical aconitase but a dehydratase. Purified PrpD was shown to be a monomeric iron–sulphur protein (M_r 54000) having one unstable [2Fe–2S] cluster per monomer, which is needed for maximum catalytic activity and can be reconstituted by treatment with Fe²⁺ under reducing conditions.

Keywords: aconitase, iron–sulphur proteins, propionate metabolism, YbhJ

Abbreviations: Acn, aconitase; c-Acn, cytoplasmic aconitase; mit-Acn, mitochondrial aconitase; AcnC, the residual Acn activity of an AcnAB-null strain; IRP, iron regulatory protein; PrpD, 2-methylcitrate dehydratase; UTR, untranslated region

This article has been cited by other articles:

				R. M. Drevland, A. Waheed, and D. E. Graham Enzymology and Evolution of the Pyruvate Pathway to 2-Oxobutyrate in Methanocaldococcus jannaschii J. Bacteriol., June 15, 2007; 189(12): 4391 - 4400. [Abstract] [Full Text] [PDF]

				S. K. Lee and J. D. Keasling A Propionate-Inducible Expression System for Enteric Bacteria Appl. Envir. Microbiol., November 1, 2005; 71(11): 6856 - 6862. [Abstract] [Full Text] [PDF]

				S. Ohlmeier, A. J. Kastaniotis, J. K. Hiltunen, and U. Bergmann The Yeast Mitochondrial Proteome, a Study of Fermentative and Respiratory Growth J. Biol. Chem., February 6, 2004; 279(6): 3956 - 3979. [Abstract] [Full Text] [PDF]

				E. T. Young, K. M. Dombek, C. Tachibana, and T. Ideker Multiple Pathways Are Co-regulated by the Protein Kinase Snf1 and the Transcription Factors Adr1 and Cat8 J. Biol. Chem., July 3, 2003; 278(28): 26146 - 26158. [Abstract] [Full Text] [PDF]

				T. Polen, D. Rittmann, V. F. Wendisch, and H. Sahm DNA Microarray Analyses of the Long-Term Adaptive Response of Escherichia coli to Acetate and Propionate Appl. Envir. Microbiol., March 1, 2003; 69(3): 1759 - 1774. [Abstract] [Full Text] [PDF]

				S. Varghese, Y. Tang, and J. A. Imlay Contrasting Sensitivities of Escherichia coli Aconitases A and B to Oxidation and Iron Depletion J. Bacteriol., January 1, 2003; 185(1): 221 - 230. [Abstract] [Full Text] [PDF]