PROSITE documentation PDOC00092
Thiolases signatures


Two different types of thiolase [1,2,3] are found both in eukaryotes and in prokaryotes: acetoacetyl-CoA thiolase (EC and 3-ketoacyl-CoA thiolase (EC 3-ketoacyl-CoA thiolase (also called thiolase I) has a broad chain-length specificity for its substrates and is involved in degradative pathways such as fatty acid β-oxidation. Acetoacetyl-CoA thiolase (also called thiolase II) is specific for the thiolysis of acetoacetyl-CoA and involved in biosynthetic pathways such as poly β-hydroxybutyrate synthesis or steroid biogenesis.

In eukaryotes, there are two forms of 3-ketoacyl-CoA thiolase: one located in the mitochondrion and the other in peroxisomes.

There are two conserved cysteine residues important for thiolase activity. The first located in the N-terminal section of the enzymes is involved in the formation of an acyl-enzyme intermediate; the second located at the C-terminal extremity is the active site base involved in deprotonation in the condensation reaction.

Mammalian nonspecific lipid-transfer protein (nsL-TP) (also known as sterol carrier protein 2) is a protein which seems to exist in two different forms: a 14 Kd protein (SCP-2) and a larger 58 Kd protein (SCP-x). The former is found in the cytoplasm or the mitochondria and is involved in lipid transport; the latter is found in peroxisomes. The C-terminal part of SCP-x is identical to SCP-2 while the N-terminal portion is evolutionary related to thiolases [4].

We developed three signature patterns for this family of proteins, two of which are based on the regions around the biologically important cysteines. The third is based on a highly conserved region in the C-terminal part of these proteins.

Last update:

April 2006 / Patterns revised.


Technical section

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

THIOLASE_1, PS00098; Thiolases acyl-enzyme intermediate signature  (PATTERN)

THIOLASE_2, PS00737; Thiolases signature 2  (PATTERN)

THIOLASE_3, PS00099; Thiolases active site  (PATTERN)


1AuthorsPeoples O.P. Sinskey A.J.
TitlePoly-beta-hydroxybutyrate biosynthesis in Alcaligenes eutrophus H16. Characterization of the genes encoding beta-ketothiolase and acetoacetyl-CoA reductase.
SourceJ. Biol. Chem. 264:15293-15297(1989).
PubMed ID2670935

2AuthorsYang S.-Y. Yang X.-Y.H. Healy-Louie G. Schulz H. Elzinga M.
TitleNucleotide sequence of the fadA gene. Primary structure of 3-ketoacyl-coenzyme A thiolase from Escherichia coli and the structural organization of the fadAB operon.
SourceJ. Biol. Chem. 265:10424-10429(1990).
PubMed ID2191949

3AuthorsIgual J.C. Gonzalez-Bosch C. Dopazo J. Perez-Ortin J.E.
TitlePhylogenetic analysis of the thiolase family. Implications for the evolutionary origin of peroxisomes.
SourceJ. Mol. Evol. 35:147-155(1992).
PubMed ID1354266

4AuthorsBaker M.E. Billheimer J.T. Strauss J.F. III
TitleSimilarity between the amino-terminal portion of mammalian 58-kD sterol carrier protein (SCPx) and Escherichia coli acetyl-CoA acyltransferase: evidence for a gene fusion in SCPx.
SourceDNA Cell Biol. 10:695-698(1991).
PubMed ID1755959

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