Publications

• Malonyl-CoA synthetase, encoded by ACYL ACTIVATING ENZYME13, is essential for growth and development of arabidopsis.

  Chen H., Kim H.U., Weng H., Browse J.

  Malonyl-CoA is the precursor for fatty acid synthesis and elongation. It is also one of the building blocks for the biosynthesis of some phytoalexins, flavonoids, and many malonylated compounds. In plants as well as in animals, malonyl-CoA is almost exclusively derived from acetyl-CoA by acetyl-Co ... >> More

  Malonyl-CoA is the precursor for fatty acid synthesis and elongation. It is also one of the building blocks for the biosynthesis of some phytoalexins, flavonoids, and many malonylated compounds. In plants as well as in animals, malonyl-CoA is almost exclusively derived from acetyl-CoA by acetyl-CoA carboxylase (EC 6.4.1.2). However, previous studies have suggested that malonyl-CoA may also be made directly from malonic acid by malonyl-CoA synthetase (EC 6.2.1.14). Here, we report the cloning of a eukaryotic malonyl-CoA synthetase gene, Acyl Activating Enzyme13 (AAE13; At3g16170), from Arabidopsis thaliana. Recombinant AAE13 protein showed high activity against malonic acid (K(m) = 529.4 ± 98.5 μM; V(m) = 24.0 ± 2.7 μmol/mg/min) but little or no activity against other dicarboxylic or fatty acids tested. Exogenous malonic acid was toxic to Arabidopsis seedlings and caused accumulation of malonic and succinic acids in the seedlings. aae13 null mutants also grew poorly and accumulated malonic and succinic acids. These defects were complemented by an AAE13 transgene or by a bacterial malonyl-CoA synthetase gene under control of the AAE13 promoter. Our results demonstrate that the malonyl-CoA synthetase encoded by AAE13 is essential for healthy growth and development, probably because it is required for the detoxification of malonate. << Less

  Plant Cell 23:2247-2262(2011) [PubMed] [EuropePMC]

• Mammalian ACSF3 protein is a malonyl-CoA synthetase that supplies the chain extender units for mitochondrial fatty acid synthesis.

  Witkowski A., Thweatt J., Smith S.

  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 ... >> More

  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. << Less

  J. Biol. Chem. 286:33729-33736(2011) [PubMed] [EuropePMC]