title: Functional analysis of mutant human carnitine acylcarnitine translocases in yeast.
abstract: Long chain fatty acids are translocated as carnitine esters across the mitochondrial inner membrane by carnitine acylcarnitine translocase (CACT). We report functional studies on the mutant CACT proteins from a severe and a mild patient with CACT deficiency. CACT activities in fibroblasts of both patients were markedly deficient with some residual activity (<1%) in the milder patient. Palmitate oxidation activity in cells from the severe patient was less than 5% but in the milder patient approximately 27% residual activity was found. Sequencing of the CACT cDNAs revealed a c.241G>A (G81R) in the severe and a c.955insC mutation (C-terminal extension of 21 amino acids (CACT(+21aa)) in the milder patient. The effect of both mutations on the protein was studied in a sensitive expression system based on the ability of human CACT to functionally complement a CACT-deletion strain of yeast. Expression in this strain revealed significant residual activity for CACT(+21aa), while the CACT(G81R) was inactive.
authors.affiliation: Department of Clinical Chemistry, Academic Medical Centre, University of Amsterdam, 1100 DE Amsterdam, The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: IJlst
authors.forename: C W
authors.initials: CW
authors.lastname: van Roermund
authors.forename: V
authors.initials: V
authors.lastname: Iacobazzi
authors.forename: W
authors.initials: W
authors.lastname: Oostheim
authors.forename: J P
authors.initials: JP
authors.lastname: Ruiter
authors.forename: J C
authors.initials: JC
authors.lastname: Williams
authors.forename: F
authors.initials: F
authors.lastname: Palmieri
authors.forename: R J
authors.initials: RJ
authors.lastname: Wanders
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002333:Carnitine Acyltransferases / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D008052:Lipid Metabolism, Inborn Errors / Q000201:enzymology / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D005227:Fatty Acids; D011994:Recombinant Proteins; D002333:Carnitine Acyltransferases