title: The mitochondrial carnitine/acylcarnitine carrier is regulated by hydrogen sulfide via interaction with C136 and C155.
abstract: BACKGROUND
  The carnitine/acylcarnitine carrier (CAC or CACT) mediates transport of acylcarnitines into mitochondria for the β-oxidation. CAC possesses Cys residues which respond to redox changes undergoing to SH/disulfide interconversion.
  
  
  METHODS
  The effect of H2S has been investigated on the [(3)H]carnitine/carnitine antiport catalyzed by recombinant or native CAC reconstituted in proteoliposomes. Site-directed mutagenesis was employed for identifying Cys reacting with H2S.
  
  
  RESULTS
  H2S led to transport inhibition, which was dependent on concentration, pH and time of incubation. Best inhibition with IC50 of 0.70 μM was observed at physiological pH after 30-60 min incubation. At longer times of incubation, inhibition was reversed. After oxidation of the carrier by O2, transport activity was rescued by H2S indicating that the inhibition/activation depends on the initial redox state of the protein. The observed effects were more efficient on the native rat liver transporter than on the recombinant protein. Only the protein containing both C136 and C155 responded to the reagent as the WT. While reduced responses were observed in the mutants containing C136 or C155. Multi-alignment of known mitochondrial carriers, highlighted that only the CAC possesses both Cys residues. This correlates well with the absence of effects of H2S on carriers which does not contain the Cys couple.
  
  
  CONCLUSIONS
  Altogether, these data demonstrate that H2S regulates the CAC by inhibiting or activating transport on the basis of the redox state of the protein.
  
  
  CONCLUSIONS
  CAC represents a specific target of H2S among mitochondrial carriers in agreement with the presence of a reactive Cys couple.
authors.affiliation: CNR Institute of Biomembranes and Bioenergetics, Via Amendola 165/A, 70126 Bari, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Giangregorio
authors.affiliation: CNR Institute of Biomembranes and Bioenergetics, Via Amendola 165/A, 70126 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, Via Bucci 4C, University of Calabria, 87036 Arcavacata di Rende, Italy.
authors.forename: Lara
authors.initials: L
authors.lastname: Console
authors.affiliation: Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Italy.
authors.forename: Imma
authors.initials: I
authors.lastname: Lorusso
authors.affiliation: Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: De Palma
authors.affiliation: Department DiBEST (Biologia, Ecologia, Scienze della Terra), Unit of Biochemistry and Molecular Biotechnology, Via Bucci 4C, University of Calabria, 87036 Arcavacata di Rende, Italy; CNR Institute of Biomembranes and Bioenergetics, Via Amendola 165/A, 70126 Bari, Italy. Electronic address: cesare.indiveri@unical.it.
authors.forename: Cesare
authors.initials: C
authors.lastname: Indiveri
mesh_terms: D000595:Amino Acid Sequence; D002333:Carnitine Acyltransferases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry*; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data
chemical_list: D002333:Carnitine Acyltransferases; D003545:Cysteine; D006862:Hydrogen Sulfide
keywords: Beta oxidation; Carnitine; Cys modification; Membrane transport; Mutagenesis; Redox biology