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	PROSITE documentation PDOC00423

Aconitase (aconitate hydratase) (EC 4.2.1.3) [1] is the enzyme from the tricarboxylic acid cycle that catalyzes the reversible isomerization of citrate and isocitrate. Cis-aconitate is formed as an intermediary product during the course of the reaction. In eukaryotes two isozymes of aconitase are known to exist: one found in the mitochondrial matrix and the other found in the cytoplasm. Aconitase, in its active form, contains a 4Fe-4S iron-sulfur cluster; three cysteine residues have been shown to be ligands of the 4Fe-4S cluster.

It has been shown that the aconitase family also contains the following proteins:

• Iron-responsive element binding protein (IRE-BP). IRE-BP is a cytosolic protein that binds to iron-responsive elements (IREs). IREs are stem-loop structures found in the 5'UTR of ferritin, and delta aminolevulinic acid synthase mRNAs, and in the 3'UTR of transferrin receptor mRNA. IRE-BP also express aconitase activity.
• 3-isopropylmalate dehydratase (EC 4.2.1.33) (isopropylmalate isomerase), the enzyme that catalyzes the second step in the biosynthesis of leucine.
• Homoaconitase (EC 4.2.1.36) (homoaconitate hydratase), an enzyme that participates in the α-aminoadipate pathway of lysine biosynthesis and that converts cis-homoaconitate into homoisocitric acid.
• Esherichia coli protein ybhJ.

As a signature for proteins from the aconitase family we have selected two conserved regions that contain the three cysteine ligands of the 4Fe-4S cluster.

Last update:

December 2004 / Pattern and text revised.

PROSITE methods (with tools and information) covered by this documentation:

ACONITASE_1, PS00450; Aconitase family signature 1  (PATTERN)

• Consensus pattern:
  [LIVM]-x(2)-[GSACIVM]-x-[LIV]-[GTIV]-[STP]-C-x(0,1)-T-N-[GSTANI]-x(4)-[LIVMA]
  C binds the iron-sulfur center
• Sequences in UniProtKB/Swiss-Prot known to belong to this class: 662
  • detected by PS00450: 633 (true positives)
  • undetected by PS00450: 29 (29 false negatives and 0 'partial')
• Other sequence(s) in UniProtKB/Swiss-Prot detected by PS00450:
  1 false positive.
• Retrieve an alignment of UniProtKB/Swiss-Prot true positive hits:
  Clustal format, color, condensed view  /  Clustal format, color  /  Clustal format, plain text  /  Fasta format
• Retrieve the sequence logo from the alignment
• Taxonomic distribution of all UniProtKB (Swiss-Prot + TrEMBL) entries matching PS00450
• Retrieve a list of all UniProtKB (Swiss-Prot + TrEMBL) entries matching PS00450
• Scan UniProtKB (Swiss-Prot and/or TrEMBL) entries against PS00450
• View ligand binding statistics of PS00450
• Matching PDB structures: 1ACO 1AMI 1AMJ 1B0J ... [ALL]

ACONITASE_2, PS01244; Aconitase family signature 2  (PATTERN)

• Consensus pattern:
  G-x(2)-[LIVWPQT]-x(3)-[GACST]-C-[GSTAM]-[LIMPTA]-C-[LIMV]-[GA]
  The 2 C's bind the iron-sulfur center
• Sequences in UniProtKB/Swiss-Prot known to belong to this class: 663
  • detected by PS01244: 637 (true positives)
  • undetected by PS01244: 26 (25 false negatives and 1 'partial')
• Other sequence(s) in UniProtKB/Swiss-Prot detected by PS01244:
  NONE.
• Retrieve an alignment of UniProtKB/Swiss-Prot true positive hits:
  Clustal format, color, condensed view  /  Clustal format, color  /  Clustal format, plain text  /  Fasta format
• Retrieve the sequence logo from the alignment
• Taxonomic distribution of all UniProtKB (Swiss-Prot + TrEMBL) entries matching PS01244
• Retrieve a list of all UniProtKB (Swiss-Prot + TrEMBL) entries matching PS01244
• Scan UniProtKB (Swiss-Prot and/or TrEMBL) entries against PS01244
• View ligand binding statistics of PS01244
• Matching PDB structures: 1ACO 1AMI 1AMJ 1B0J ... [ALL]

1	Authors	Gruer M.J., Artymiuk P.J., Guest J.R.
	Title	The aconitase family: three structural variations on a common theme.
	Source	Trends Biochem. Sci. 22:3-6(1997).
	PubMed ID	9020582

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