Witkowski 2011 J Biol Chem
|Witkowski A, Thweatt J, Smith S (2011) Mammalian ACSF3 protein is a malonyl-CoA synthetase that supplies the chain extender units for mitochondrial fatty acid synthesis. J Biol Chem 286:33729-36.|
Abstract: The objective of this study was to identify a source of intramitochondrial malonyl-CoA that could be used for de novo fatty acid synthesis in mammalian mitochondria. Because mammalian mitochondria lack an acetyl-CoA carboxylase capable of generating malonyl-CoA inside mitochondria, the possibility that malonate could act as a precursor was investigated. Although malonyl-CoA synthetases have not been identified previously in animals, interrogation of animal protein sequence databases identified candidates that exhibited sequence similarity to known prokaryotic forms. The human candidate protein ACSF3, which has a predicted N-terminal mitochondrial targeting sequence, was cloned, expressed, and characterized as a 65-kDa acyl-CoA synthetase with extremely high specificity for malonate and methylmalonate. An arginine residue implicated in malonate binding by prokaryotic malonyl-CoA synthetases was found to be positionally conserved in animal ACSF3 enzymes and essential for activity. Subcellular fractionation experiments with HEK293T cells confirmed that human ACSF3 is located exclusively in mitochondria, and RNA interference experiments verified that this enzyme is responsible for most, if not all, of the malonyl-CoA synthetase activity in the mitochondria of these cells. In conclusion, unlike fungi, which have an intramitochondrial acetyl-CoA carboxylase, animals require an alternative source of mitochondrial malonyl-CoA; the mitochondrial ACSF3 enzyme is capable of filling this role by utilizing free malonic acid as substrate.
• Keywords: Malonyl-CoA; Malonyl-CoA synthetase • Bioblast editor: Garcia-Souza LF
Labels: MiParea: Genetic knockout;overexpression
Organism: Human Tissue;cell: HEK Preparation: Isolated mitochondria
- Malonyl-CoA is formed from acetyl CoA by the action of acetyl-CoA carboxylase. This paper shows that mammals express Malonyl-CoA Synthetase (ACSF3) with enzymatic activity in the presence of malate and methylmalonate.