{PDOC00092}
{PS00098; THIOLASE_1}
{PS00737; THIOLASE_2}
{PS00099; THIOLASE_3}
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* Thiolases signatures *
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Two different  types  of thiolase [1,2,3] are found  both in eukaryotes and in
prokaryotes: acetoacetyl-CoA thiolase (EC 2.3.1.9) and 3-ketoacyl-CoA thiolase
(EC 2.3.1.16).  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  beta-oxidation.  Acetoacetyl-CoA thiolase (also
called thiolase  II)  is  specific  for  the  thiolysis of acetoacetyl-CoA and
involved in biosynthetic pathways such  as poly beta-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.

-Consensus pattern: [LIVM]-[NST]-{T}-x-C-[SAGLI]-[ST]-[SAG]-[LIVMFYNS]-x-
                    [STAG]-[LIVM]-x(6)-[LIVM]
                    [C is involved in formation of acyl-enzyme intermediate]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: 5.

-Consensus pattern: N-x(2)-G(2)-x-[LIVM]-[SA]-x-G-H-P-x-[GAS]-x-[ST]-G
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Consensus pattern: [AG]-[LIVMA]-[STAGCLIVM]-[STAG]-[LIVMA]-C-{Q}-[AG]-x-[AG]-
                    x-[AG]-x-[SAG]
                    [C is the active site residue]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for nsL-TP.
-Other sequence(s) detected in Swiss-Prot: 8.

-Last update: April 2006 / Patterns revised.

[ 1] Peoples O.P., Sinskey A.J.
     "Poly-beta-hydroxybutyrate biosynthesis in Alcaligenes eutrophus H16.
     Characterization of the genes encoding beta-ketothiolase and
     acetoacetyl-CoA reductase."
     J. Biol. Chem. 264:15293-15297(1989).
     PubMed=2670935
[ 2] Yang S.-Y., Yang X.-Y.H., Healy-Louie G., Schulz H., Elzinga M.
     "Nucleotide sequence of the fadA gene. Primary structure of
     3-ketoacyl-coenzyme A thiolase from Escherichia coli and the
     structural organization of the fadAB operon."
     J. Biol. Chem. 265:10424-10429(1990).
     PubMed=2191949
[ 3] Igual J.C., Gonzalez-Bosch C., Dopazo J., Perez-Ortin J.E.
     "Phylogenetic analysis of the thiolase family. Implications for the
     evolutionary origin of peroxisomes."
     J. Mol. Evol. 35:147-155(1992).
     PubMed=1354266
[ 4] Baker M.E., Billheimer J.T., Strauss J.F. III
     "Similarity 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."
     DNA Cell Biol. 10:695-698(1991).
     PubMed=1755959

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