title: Post-translational modification by acetylation regulates the mitochondrial carnitine/acylcarnitine transport protein.
abstract: The carnitine/acylcarnitine transporter (CACT; SLC25A20) mediates an antiport reaction allowing entry of acyl moieties in the form of acylcarnitines into the mitochondrial matrix and exit of free carnitine. The transport function of CACT is crucial for the β-oxidation pathway. In this work, it has been found that CACT is partially acetylated in rat liver mitochondria as demonstrated by anti-acetyl-lys antibody immunostaining. Acetylation was reversed by the deacetylase Sirtuin 3 in the presence of NAD+. After treatment of the mitochondrial extract with the deacetylase, the CACT activity, assayed in proteoliposomes, increased. The half-saturation constant of the CACT was not influenced, while the Vmaxwas increased by deacetylation. Sirtuin 3 was not able to deacetylate the CACT when incubation was performed in intact mitoplasts, indicating that the acetylation sites are located in the mitochondrial matrix. Prediction on the localization of acetylated residues by bioinformatics correlates well with the experimental data. Recombinant CACT treated with acetyl-CoA was partially acetylated by non-enzymatic mechanism with a corresponding decrease of transport activity. The experimental data indicate that acetylation of CACT inhibits its transport activity, and thus may contribute to the regulation of the mitochondrial β-oxidation pathway.
authors.affiliation: CNR Institute of Biomembranes and Bioenergetics, Via Amendola 165/A, 70126, Bari, Italy. n.giangregorio@ibbe.cnr.it.|Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy. n.giangregorio@ibbe.cnr.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Giangregorio
authors.affiliation: CNR Institute of Biomembranes and Bioenergetics, Via Amendola 165/A, 70126, Bari, Italy.|Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Bari, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Tonazzi
authors.affiliation: Department DiBEST (Biologia, Ecologia, Scienze Della Terra), Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci cubo 4C, 87036, Arcavacata di Rende, CS, Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Console
authors.affiliation: Department DiBEST (Biologia, Ecologia, Scienze Della Terra), Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via Bucci cubo 4C, 87036, Arcavacata di Rende, CS, Italy. cesare.indiveri@unical.it.
authors.forename: Cesare
authors.identifier: http://orcid.org/0000-0001-9818-6621
authors.initials: C
authors.lastname: Indiveri
mesh_terms: D000107:Acetylation; D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D002333:Carnitine Acyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009243:NAD / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D056566:Sirtuin 3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D024101:Mitochondrial Proteins; D011994:Recombinant Proteins; D009243:NAD; D002333:Carnitine Acyltransferases; C000602144:Slc25a20 protein, rat; D056566:Sirtuin 3
keywords: Beta-oxidation; Carnitine; Fatty acids; Liposomes; Membrane transport; Sirtuins