Mutagenesis of specific amino acids converts carnitine acetyltransferase into carnitine palmitoyltransferase.

Article Details

Citation

Copy to clipboard

Cordente AG, Lopez-Vinas E, Vazquez MI, Gomez-Puertas P, Asins G, Serra D, Hegardt FG

Mutagenesis of specific amino acids converts carnitine acetyltransferase into carnitine palmitoyltransferase.

Biochemistry. 2006 May 16;45(19):6133-41.

PubMed ID

16681386 [ View in PubMed

]

Abstract

Carnitine acyltransferases catalyze the exchange of acyl groups between carnitine and CoA. The members of the family can be classified on the basis of their acyl-CoA selectivity. Carnitine acetyltransferases (CrATs) are very active toward short-chain acyl-CoAs but not toward medium- or long-chain acyl-CoAs. Previously, we identified an amino acid residue (Met(564) in rat CrAT) that was critical to fatty acyl-chain-length specificity. M564G-mutated CrAT behaved as if its natural substrates were medium-chain acyl-CoAs, similar to that of carnitine octanoyltransferase (COT). To extend the specificity of rat CrAT to other substrates, we have performed new mutations. Using in silico molecular modeling procedures, we have now identified a second putative amino acid involved in acyl-CoA specificity (Asp(356) in rat CrAT). The double CrAT mutant D356A/M564G showed 6-fold higher activity toward palmitoyl-CoA than that of the single CrAT mutant M564G and a new activity toward stearoyl-CoA. We show that by performing two amino acid replacements a CrAT can be converted into a pseudo carnitine palmitoyltransferase (CPT) in terms of substrate specificity. To change CrAT specificity from carnitine to choline, we also prepared a mutant CrAT that incorporates four amino acid substitutions (A106M/T465V/T467N/R518N). The quadruple mutant shifted the catalytic discrimination between l-carnitine and choline in favor of the latter substrate and showed a 9-fold increase in catalytic efficiency toward choline compared with that of the wild-type. Molecular in silico docking supports kinetic data for the positioning of substrates in the catalytic site of CrAT mutants.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Levocarnitine	Peroxisomal carnitine O-octanoyltransferase	Protein	Humans	Unknown	Not Available	Details