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Isocitrate lyase (EC 4.1.3.1) [1,2] is an enzyme that catalyzes the conversion of isocitrate to succinate and glyoxylate. This is the first step in the glyoxylate bypass, an alternative to the tricarboxylic acid cycle in bacteria, fungi and plants.

A cysteine, a histidine and a glutamate or aspartate have been found to be important for the enzyme's catalytic activity. Only one cysteine residue is conserved between the sequences of the fungal, plant and bacterial enzymes; it is located in the middle of a conserved hexapeptide that can be used as a signature pattern for this type of enzyme.

ICL is evolutionary related to two other type of enzymes:

• Carboxyphosphonoenolpyruvate phosphonomutase (EC 2.7.8.23) (CPEP mutase). It forms a carbon-phosphorus bond in a rearrangement leading from carboxyphosphonoenolpyruvate (CPEP) to phosphinopyruvate.
• Phosphoenolpyruvate phosphomutase (EC 5.4.2.9) (PEP mutase) [3]. It forms a carbon-phosphorus bond by converting phosphoenolpyruvate (PEP) to phosphonopyruvate.

May 2004 / Text revised.

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

ISOCITRATE_LYASE, PS00161; Isocitrate lyase signature  (PATTERN)

Consensus pattern: K-[KR]-C-G-H-[LMQR] C may be an active site residue Sequences known to belong to this class detected by the pattern: All ICLs and CPEP mutases, but not PEP mutases Other sequence(s) detected in Swiss-Prot: NONE

• Retrieve an alignment of 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 tree view of all Swiss-Prot/TrEMBL entries matching PS00161 • Retrieve a list of all Swiss-Prot/TrEMBL entries matching PS00161 • Scan Swiss-Prot/TrEMBL entries against PS00161 • view ligand binding statistics

Matching PDB structures: 1F61 1F8M 1IGW 1MUM ... [ALL]

1	Authors	Beeching J.R.
	Title	High sequence conservation between isocitrate lyase from Escherichia coli and Ricinus communis.
	Source	Protein Seq. Data Anal. 2:463-466(1989).
	PubMed ID	2696959

2	Authors	Atomi H., Ueda M., Hikida M., Hishida T., Teranishi Y., Tanaka A.
	Title	Peroxisomal isocitrate lyase of the n-alkane-assimilating yeast Candida tropicalis: gene analysis and characterization.
	Source	J. Biochem. 107:262-266(1990).
	PubMed ID	2361956

3	Authors	Huang K., Li Z., Jia Y., Dunaway-Mariano D., Herzberg O.
	Title	Helix swapping between two alpha/beta barrels: crystal structure of phosphoenolpyruvate mutase with bound Mg(2+)-oxalate.
	Source	Structure 7:539-548(1999).
	PubMed ID	10378273

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