Crystal structure of carnitine acetyltransferase and implications for the catalytic mechanism and fatty acid transport.
Carnitine acyltransferases have crucial roles in the transport of fatty acids for beta-oxidation. Dysregulation of these enzymes can lead to serious diseases in humans, and they are targets for therapeutic development against diabetes. We report the crystal structures of murine carnitine acetyltransferase (CRAT), alone and in complex with its substrate carnitine or CoA. The structure contains two domains. Surprisingly, these two domains share the same backbone fold, which is also similar to that of chloramphenicol acetyltransferase and dihydrolipoyl transacetylase. The active site is located at the interface between the two domains. Carnitine and CoA are bound in deep channels in the enzyme, on opposite sides of the catalytic His343 residue. The structural information provides a molecular basis for understanding the catalysis by carnitine acyltransferases and for designing their inhibitors. Specifically, our structural information suggests that the substrate carnitine may assist the catalysis by stabilizing the oxyanion in the reaction intermediate.
Jogl
Gerwald
G
Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Tong
Liang
L
D000217:Acyltransferases / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001693:Biological Transport, Active; D002332:Carnitine O-Acetyltransferase / Q000737:chemistry* / Q000302:isolation & purification; D002334:Carnitine O-Palmitoyltransferase / Q000737:chemistry; D002384:Catalysis; D015500:Chloramphenicol O-Acetyltransferase / Q000737:chemistry; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D004926:Escherichia coli; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013379:Substrate Specificity
D005227:Fatty Acids; D000217:Acyltransferases; C033588:dihydrolipoamide acyltransferase; D002334:Carnitine O-Palmitoyltransferase; D015500:Chloramphenicol O-Acetyltransferase; D002332:Carnitine O-Acetyltransferase