Site-directed mutagenesis of charged amino acids of the human mitochondrial carnitine/acylcarnitine carrier: Insight into the molecular mechanism of transport. (Articolo in rivista)

Type
Label
  • Site-directed mutagenesis of charged amino acids of the human mitochondrial carnitine/acylcarnitine carrier: Insight into the molecular mechanism of transport. (Articolo in rivista) (literal)
Anno
  • 2010-01-01T00:00:00+01:00 (literal)
Alternative label
  • Giangregorio N; Tonazzi A; Console L; Indiveri C; Palmieri F (2010)
    Site-directed mutagenesis of charged amino acids of the human mitochondrial carnitine/acylcarnitine carrier: Insight into the molecular mechanism of transport.
    in Biochimica et biophysica acta. Bioenergetics
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Giangregorio N; Tonazzi A; Console L; Indiveri C; Palmieri F (literal)
Pagina inizio
  • 839 (literal)
Pagina fine
  • 845 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 1797 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • CNR, Inst Biomembranes & Bioenerget, I-70125 Bari, Italy Univ Calabria, Dept Cellular Biol, I-87036 Arcavacata Di Rende, Italy Univ Bari, Dept Pharmacobiol, Lab Biochem & Mol Biol, I-70125 Bari, Italy (literal)
Titolo
  • Site-directed mutagenesis of charged amino acids of the human mitochondrial carnitine/acylcarnitine carrier: Insight into the molecular mechanism of transport. (literal)
Abstract
  • The structure/function relationships of charged residues of the human mitochondrial carnitine/acylcarnitine carrier, which are conserved in the carnitine/acylcarnitine carrier subfamily and exposed to the water-filled cavity of carnitine/acylcarnitine carrier in the c-state, have been investigated by site-directed mutagenesis. The mutants were expressed in Escherichia coil, purified and reconstituted in liposomes, and their transport activity was measured as (3)H-carnitine/carnitine antiport. The mutants K35A, E132A, D179A and R275A were nearly inactive with transport activities between 5 and 10% of the wild-type carnitine/acylcarnitine carrier. R178A, K234A and D231A showed transport function of about 15% of the wild-type carnitine/acylcarnitine carrier. The substitutions of the other residues with alanine had little or no effect on the carnitine/acylcarnitine carrier activity. Marked changes in the kinetic parameters with three-fold higher Km and lower Vmax values with respect to the wild-type carnitine/acylcarnitine carrier were found when replacing Lys-35, Glu-132, Asp-179 and Arg-275 with alanine. Double mutants exhibited transport activities and kinetic parameters reflecting those of the single mutants; however, lack of D179A activity was partially rescued by the additional mutation R178A. The results provide evidence that Arg-275, Asp-179 and Arg-178, which protrude into the carrier's internal cavity at about the midpoint of the membrane, are the critical binding sites for carnitine. Furthermore, Lys-35 and Glu-132, which are very probably involved in the salt-bridge network located at the bottom of the cavity, play a major role in opening and closing the matrix gate. (literal)
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