Conserved Site

Octanoyltransferase, conserved site (IPR020605)

Short name: Octanoyltransferase_CS

Description

Lipoate-protein ligase B [PMID: 8002607] (gene lipB), alternatively known as octanoyltransferase (EC:2.3.1.181) is an enzyme that creates an amide linkage that joins the free carboxyl group of lipoic acid to the epsilon-amino group of a specific lysine residue in lipoate-dependent enzymes.

octanoyl-[acyl-carrier-protein] + protein = protein N6-(octanoyl)lysine + acyl carrier protein

Lipoyl(octanoyl) transferase catalyses the first committed step in the biosynthesis of lipoyl cofactor. The lipoyl cofactor is essential for the function of several key enzymes involved in oxidative metabolism, as it converts apoprotein into the biologically active holoprotein. Examples of such lipoylated proteins include pyruvate dehydrogenase (E2 domain), 2-oxoglutarate dehydrogenase (E2 domain), the branched-chain 2-oxoacid dehydrogenases and the glycine cleavage system (H protein) [PMID: 1655709, PMID: 921841]. Lipoyl-ACP can also act as a substrate [PMID: 14700636] although octanoyl-ACP is likely to be the true substrate [PMID: 10966480]. The other enzyme involved in the biosynthesis of lipoyl cofactor is EC:2.8.1.8, lipoyl synthase. An alternative lipoylation pathway involves EC:2.7.7.63, lipoate-protein ligase, which can lipoylate apoproteins using exogenous lipoic acid (or its analogues).

Such an enzyme has also been found in fungi [PMID: 9268025], where it is located in the mitochondria. It also seems to exist in plants [PMID: 11427685] and is encoded in the chloroplast genome of the red alga Cyanidium caldarium [PMID: 11040290].

This entry represents a conserved region, located in the central part of the enzyme; this region contains one of two conserved histidines.

GO terms

Biological Process

GO:0009107 lipoate biosynthetic process

Molecular Function

GO:0016415 octanoyltransferase activity

Cellular Component

GO:0005737 cytoplasm

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns