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Escherichia coli K-12 substr. MG1655 Protein Class: a [citrate-lyase]

Synonyms: deacetyl-[citrate-oxaloacetate-lyase((pro-3S)-CH2COO-acetate)]

Superclasses: a protein a modified protein [a holo citrate lyase acyl-carrier protein]
a protein complex [a holo citrate lyase acyl-carrier protein]

Summary:
Citrate lyase, an anaerobic enzyme, catalyzes the cleavage of citrate to acetate and oxaloacetate [Nilekani83]. The citrate molecule is very stable, and needs to be activated prior to cleavage by forming a thioester bond with the enzyme.

The enzyme is a complex of three subunits (in a 6:6:6 configuration), one of them a dedicated acyl carrier protein (acp). It is synthesized in an apo form, and is converted to its holo form by the covalent binding of the unusual prosthetic group 2'-(5''-phosphoribosyl)-3'-dephospho-CoA to the [acp] component, resulting in a [citrate-lyase]. However, this holo form is still not fully active - in order to be active, the prosthetic group needs to be acetylated, a reaction catalyzed by the citC-encoded citrate lyase synthetase, which generates an acetyl-[holo citrate lyase acyl-carrier protein].

The α subunit of the citrate lyase is a citrate-[acp] transferase that catalyzes the exchange of the bound acetyl group with a citrate molecule, generating a citryl-[holo citrate lyase acyl-carrier protein] and releasing an acetate molecule. The β subunit, which is a citryl-[acp] lyase, catalyzes the subsequent step, cleaving the bound citryl group, releasing oxaloacetate and regenerating an acetyl-[holo citrate lyase acyl-carrier protein]. Since the active form is regenrated, the enzyme can continuously catalyze the cleavage reaction.

Instances:
citrate lyase, inactive

Alternative forms of a [citrate-lyase]:
a citryl-[holo citrate lyase acyl-carrier protein] (extended summary available)
a [citrate-lyase] (citryl form) (extended summary available)

Reactions known to consume the compound:

citrate lyase activation :
[a holo citrate lyase acyl-carrier protein] + acetate + ATP → an acetyl-[holo citrate lyase acyl-carrier protein] + AMP + diphosphate
[a holo citrate lyase acyl-carrier protein] + S-acetyl phosphopantetheine → an acetyl-[holo citrate lyase acyl-carrier protein] + 4'-phosphopantetheine

Reactions known to produce the compound:

citrate lyase activation :
an acetyl-[holo citrate lyase acyl-carrier protein] + 6 H2O → [a holo citrate lyase acyl-carrier protein] + 6 acetate
2'-(5''-triphospho-α-D-ribosyl)-3'-dephospho-CoA + [an apo citrate-lyase acyl-carrier protein] → [a holo citrate lyase acyl-carrier protein] + diphosphate

Gene-Reaction Schematic: ?


References

Nilekani83: Nilekani S, SivaRaman C (1983). "Purification and properties of citrate lyase from Escherichia coli." Biochemistry 1983;22(20);4657-63. PMID: 6354265


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
Page generated by SRI International Pathway Tools version 18.5 on Fri Dec 19, 2014, BIOCYC14A.