Acetyl-CoA—Life at the metabolic nexus

As a key intermediate in a number of different metabolic pathways, acetyl-CoA is independently produced and consumed in the plastids, mitochondria, peroxisomes and cytosol. Recent studies have led to new understanding of the enzymes that generate these different acetyl-CoA pools, including the role of ATP-citrate lyase in producing acetyl-CoA in the cytosol and of the pyruvate dehydrogenase complex for making it in the plastids. The involvement of a second plastid enzyme, acetyl-CoA synthetase, is more speculative but appears to be important in protecting plants from the two-carbon intermediates of fermentation by allowing the conversion of ethanol and acetaldehyde to fatty acids. New roles have also recently been proposed for triacylglycerols in energy storage and oil production in leaves. While additional biological functions for acetyl-CoA are being discovered there are also new proposals for using the chemistry of acetyl-CoA and fatty acid synthesis as the foundation for a new biologically based source of commodity chemicals.