Identification of the two histidine residues responsible for the inhibition by malonyl‐CoA in peroxisomal carnitine octanoyltransferase from rat liver

FEBS Letters

Ariño, Joaquı́n¹  Clotet, Josep¹  Morillas, Montserrat²  Asins, Guillermina²  Hegardt, Fausto G.²  Serra, Dolors²  Rubı́, Blanca² 

[1] Department of Biochemistry and Molecular Biology, Autonomous University of Barcelona, School of Veterinary Medicine, 08193 Bellaterra, Spain;Department of Biochemistry and Molecular Biology, University of Barcelona, School of Pharmacy, Diagonal 643, 08028 Barcelona, Spain

关键词: Malonyl-coenzyme A;    Peroxisome;    Carnitine octanoyltransferase;    Inhibitory kinetics;    Site-directed mutagenesis;    Rat liver;    COT;    carnitine octanoyltransferase;    CPT;    carnitine palmitoyltransferase;    CM(−ura);    complete minimal medium lacking uracil;   

DOI  :  10.1016/S0014-5793(99)01788-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Carnitine octanoyltransferase (COT), an enzyme that facilitates the transport of medium chain fatty acids through peroxisomal membranes, is inhibited by malonyl-CoA. cDNAs encoding full-length wild-type COT and one double mutant variant from rat peroxisomal COT were expressed in Saccharomyces cerevisiae. Both expressed forms were expressed similarly in quantitative terms and exhibited full enzyme activity. The wild-type-expressed COT was inhibited by malonyl-CoA like the liver enzyme. The activity of the enzyme encoded by the double mutant H131A/H340A was completely insensitive to malonyl-CoA in the range assayed (2–200 μM). These results indicate that the two histidine residues, H131 and H340, are the sites responsible for inhibition by malonyl-CoA. Another mutant variant, H327A, abolishes the enzyme activity, from which it is concluded that it plays an important role in catalysis.

【 授权许可】

Unknown