Premium
Identification of the two histidine residues responsible for the inhibition by malonyl‐CoA in peroxisomal carnitine octanoyltransferase from rat liver
Author(s) -
Morillas Montserrat,
Clotet Josep,
Rubı́ Blanca,
Serra Dolors,
Asins Guillermina,
Ariño Joaquı́n,
Hegardt Fausto G.
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01788-3
Subject(s) - malonyl coa , peroxisome , biochemistry , histidine , enzyme , mutant , saccharomyces cerevisiae , chemistry , carnitine , enzyme assay , biology , gene , beta oxidation
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.