Note. The novel nucleotide sequence data published here have been deposited with the EMBL sequence data bank and are available under the accession numbers X60239 E.COLI ACN, CYSB and RIBA.
The aconitase of Escherichia coli
Nucleotide sequence of the aconitase gene and amino acid sequence similarity with mitochondrial aconitases, the iron-responsive-element-binding protein and isopropylmalate isomerases
Article first published online: 3 MAR 2005
European Journal of Biochemistry
Volume 204, Issue 2, pages 599–609, March 1992
How to Cite
PRODROMOU, C., ARTYMIUK, P. J. and GUEST, J. R. (1992), The aconitase of Escherichia coli. European Journal of Biochemistry, 204: 599–609. doi: 10.1111/j.1432-1033.1992.tb16673.x
- Issue published online: 3 MAR 2005
- Article first published online: 3 MAR 2005
- (Received September 10, 1991) – EJB 91 1210
The nucleotide sequence of the aconitase gene (acn) of Escherichia coli was determined and used to deduce the primary structure of the enzyme. The coding region comprises 2670 bp (890 codons excluding the start and stop codons) which define a product having a relative molecular mass of 97513 and an N-terminal amino acid sequence consistent with those determined previously for the purified enzyme. The acn gene is flanked by the cysB gene and a putative riboflavin biosynthesis gene resembling the ribA gene of Bacillus subtillis. The 1004-bp cysB–acn intergenic region contains several potential promoter and regulatory sequences.
The amino acid sequence of the E. coli aconitase is similar to the mitochondrial aconitases (27–29% identity) and the isopropylmalate isomerases (20–21% identity) but it is most similar to the human iron-responsive-element-binding protein (53% identity). The three cysteine residues involved in ligand binding to the [4Fe-4S] centre are conserved in all of these proteins. Of the remaining 17 active-site residues assigned for porcine aconitase, 16 are conserved in both the bacterial aconitase and the iron-responsive-element-binding protein and 14 in the isopropylmalate isomerases. It is concluded that the bacterial and mitochondrial aconitases, the isopropylmalate isomerases and the iron-responsive-element-binding protein form a family of structurally related proteins, which does not include the Fe-S-containing fumarases. These relationships raise the possibility that the iron-responsive-element-binding protein may be a cytoplasmic aconitase and that the E. coli aconitase may have an iron-responsive regulatory function.