InterPro domain: IPR036736

Acyl carrier protein (ACP) is an essential cofactor in the synthesis of fatty acids by the fatty acid synthetases systems in bacteria and plants. In addition to fatty acid synthesis, ACP is also involved in many other reactions that require acyl transfer steps, such as the synthesis of polyketide antibiotics, biotin precursor, membrane-derived oligosaccharides, and activation of toxins, and functions as an essential cofactor in lipoylation of pyruvate and alpha-ketoglutarate dehydrogenase complexes [ 1 ]. Phosphopantetheine (or pantetheine 4' phosphate) is the prosthetic group of acyl carrier proteins (ACP) in some multienzyme complexes where it serves as a 'swinging arm' for the attachment of activated fatty acid and amino-acid groups [ 2 ]. Phosphopantetheine is attached to a serine residue in these proteins. The core structure of ACP consists of a four-helical bundle, where helix three is shorter than the others.

Several other proteins share structural homology with ACP, such as the bacterial apo-D-alanyl carrier protein, which facilitates the incorporation of D-alanine into lipoteichoic acid by a ligase, necessary for the growth and development of Gram-positive organisms [ 3 ]; and the thioester domain of the bacterial peptide carrier protein (PCP) found within large modular non-ribosomal peptide synthetases, which are responsible for the synthesis of a variety of microbial bioactive peptides [ 4 ].

1. X-ray crystallographic studies on butyryl-ACP reveal flexibility of the structure around a putative acyl chain binding site. Structure 10, 825-35
2. Acyl-carrier protein-phosphopantetheinyltransferase partnerships in fungal fatty acid synthases. Chembiochem 9, 1559-63
3. Biosynthesis of D-alanyl-lipoteichoic acid: the tertiary structure of apo-D-alanyl carrier protein. Biochemistry 40, 7964-72
4. Solution structure of PCP, a prototype for the peptidyl carrier domains of modular peptide synthetases. Structure 8, 407-18