Engineering Acyl Carrier Protein Enhances Production of Short Fatty Acids

The acyl carrier protein (ACP) is an essential component in the synthesis of fatty acids, the precursor of biofuels. Natural fatty acids usually have long carbon chains. However, shorter carbon chains are desired for internal combustion engines.  Xueliang Liu and Wade M. Hicks from Harvard University and Harvard Medical School, respectively, tested if engineering the length of proteins in fatty acid metabolism may enable microbial synthesis of shorter fatty acids.

The team constructed a model of the Synechococcus elongatus ACP. Amino acids were then mutated to increase steric hindrance to the acyl chain. Certain mutant ACPs, when overexpressed in Escherichia coli, increased the proportion of shorter chain lipids; Mutants I75W and I75Y showed the strongest effects. Expression of these mutant ACPs also increased production of lauric acid in E. coli.

The team engineered the specificity of the ACP to alter the E. coli lipid pool and enhance production of medium-chain fatty acids as biofuel precursors. These indicate that modification of ACP itself could be used to enhance production of commodity chemicals based on fatty acids.