Holo-(acyl-carrier-protein) synthase

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holo-[acyl-carrier-protein] synthase trimer, Helicobacter pylori
EC no.
CAS no.37278-30-1
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
PDB 1qr0 EBI.jpg
crystal structure of the 4'-phosphopantetheinyl transferase sfp-coenzyme a complex

In enzymology and molecular biology, a holo-[acyl-carrier-protein] synthase (ACPS, EC is an enzyme that catalyzes the chemical reaction:

CoA-[4'-phosphopantetheine] + apo-acyl carrier protein adenosine 3',5'-bisphosphate + holo-acyl carrier protein

This enzyme belongs to the family of transferases, specifically those transferring non-standard substituted phosphate groups. It is also known as 4'-phosphopantetheinyl transferase after the group it transfers.


All ACPS enzymes known so far are evolutionally related to each other in a single superfamily of proteins. It transfers a 4'-phosphopantetheine (4'-PP) moiety from coenzyme A (CoA) to an invariant serine in an acyl carrier protein (ACP), a small protein responsible for acyl group activation in fatty acid biosynthesis. This post-translational modification renders holo-ACP capable of acyl group activation via thioesterification of the cysteamine thiol of 4'-PP.[1] This superfamily consists of two subtypes: the trimeric ACPS type such as E. coli ACPS and the monomeric Sfp (PCP-synthesizing) type such as B. subtilis SFP. Structures from both families are now known. The active site accommodates a magnesium ion. The most highly conserved regions of the protein are involved in binding the magnesium ion.[2][3]


The systematic name of this enzyme class is CoA-[4'-phosphopantetheine]:apo-[acyl-carrier-protein] 4'-pantetheinephosphotransferase. Other names in common use, disregarding the synthetase/synthase spelling difference, include acyl carrier protein holoprotein synthetase, holo-ACP synthetase, coenzyme A:fatty acid synthetase apoenzyme 4'-phosphopantetheine, acyl carrier protein synthetase (ACPS), PPTase, acyl carrier protein synthase, P-pant transferase, and CoA:apo-[acyl-carrier-protein] pantetheinephosphotransferase.

Structural studies[edit]

As of late 2007, 8 structures have been solved for this class of enzymes, with PDB accession codes 1F7L, 1F7T, 1F80, 1FTE, 1FTF, 1FTH, 2JBZ, and 2JCA.


  1. ^ Lambalot RH, Walsh CT (October 1995). "Cloning, overproduction, and characterization of the Escherichia coli holo-acyl carrier protein synthase". The Journal of Biological Chemistry. 270 (42): 24658–61. doi:10.1074/jbc.270.42.24658. PMID 7559576.
  2. ^ Reuter K, Mofid MR, Marahiel MA, Ficner R (December 1999). "Crystal structure of the surfactin synthetase-activating enzyme sfp: a prototype of the 4'-phosphopantetheinyl transferase superfamily". The EMBO Journal. 18 (23): 6823–31. doi:10.1093/emboj/18.23.6823. PMC 1171745. PMID 10581256.
  3. ^ Marcella AM, Culbertson SJ, Shogren-Knaak MA, Barb AW (24 November 2017). "Structure, High Affinity, and Negative Cooperativity of the Escherichia coli Holo-(Acyl Carrier Protein):Holo-(Acyl Carrier Protein) Synthase Complex". Journal of Molecular Biology. 429 (23): 3763–3775. doi:10.1016/j.jmb.2017.10.015. PMID 29054754.

Further reading[edit]

This article incorporates text from the public domain Pfam and InterPro: IPR008278