Acyl carrier protein

Streptomyces coelicolor actinorhodin polyketide synthase acyl carrier protein - PDB: 2AF8

The acyl carrier protein (ACP) is an important component in both fatty acid and polyketide biosynthesis with the growing chain bound during synthesis as a thiol ester at the distal thiol of a 4'-phosphopantetheine moiety. The protein is expressed in the inactive apo form and the 4'-phosphopantetheine moiety must be post-translationally attached to a conserved serine residue on the ACP by the action of holo-acyl carrier protein synthase (ACPS), a phosphopantetheinyl transferase.

4'-Phosphopantetheine is an essential prosthetic group of several acyl carrier proteins involved in pathways of primary and secondary metabolism including the acyl carrier proteins (ACP) of fatty acid synthases, ACPs of polyketide synthases, and peptidyl carrier proteins (PCP) and aryl carrier proteins (ArCP) of nonribosomal peptide synthetases (NRPS). Phosphopantetheine fulfills two demands in these biosynthetic pathways. First, the intermediates remain covalently linked to the synthases (or synthetases) in an energy-rich linkage. Second, the flexibility and length of the phosphopantetheine chain (approximately 2 nm) allows the covalently tethered intermediates to have access to spatially distinct enzyme-active sites. This increases the effective molarity of the intermediate and allows an assembly line-like process.

The ACPs are small negatively charged α-helical bundle proteins with a high degree of structural and amino acid similarity. The structures of a number of acyl carrier proteins have been solved using various NMR and crystallography techniques.

The ACPs are related in structure and mechanism to the peptidyl carrier proteins (PCP) from nonribosomal peptide synthases.

External links

Acyl Carrier Protein at the US National Library of Medicine Medical Subject Headings (MeSH)

Proteins: carrier proteins

Fatty acid	FABP1 FABP2 FABP3 FABP4 FABP5 FABP6 FABP7

Hormone	peptide hormone: Follistatin Growth hormone binding protein Insulin-like growth factor binding protein IGFBP1 IGFBP2 IGFBP3 IGFBP4 IGFBP5 IGFBP6 IGFBP7 Neurophysins Neurophysin I II steroid hormone: Sex hormone binding globulin/Androgen binding protein Transcortin Thyroxine-binding globulin Transthyretin

Metal/element	calcium Calcium-binding protein Calmodulin-binding proteins copper Ceruloplasmin iron Iron-binding proteins Transferrin receptor

Vitamin	Retinol binding protein 1 2 3 4 Transcobalamin

Pigment	Plant Light-Harvesting Complex Orange Carotenoid Protein Phycobiliprotein Photosynthetic Reaction Centers Phytochrome Rhodopsin

Other	Acyl carrier protein Adaptor protein Cholesterylester transfer protein F-box protein GTP-binding protein Latent TGF-beta binding protein Major urinary proteins Membrane transport protein Odorant binding protein

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