| abstract |
Methods of altering substrate specificity of plant acyl-ACP thioesterases, and engineered plant acyl-ACP thioesterases so produced are provided. The C-terminal two thirds portion of plant thioesterases is identified as desirable for such modifications. DNA sequences and constructs for expression of engineered thioesterases, as well as the novel thioesterases produced therefrom are also provided. Such DNA sequences may be used for expression of the engineered thioesterases in host cells, particularly seed cells of oilseed crop plants, for the modification of fatty acid composition. A C12 preferring plant acyl-ACP thioesterase described herein may be altered to obtain a plant thioesterase having approximately equal activity on C14 and C12 substrates. Further modification of the C12 enzyme yields a thioesterase having greater activity on C14 as compared to C12 substrates. Also provided in the instant invention are novel plant acyl-ACP thioesterase sequences from Cuphea palustris and mangosteen (Garcinia mangifera), which demonstrate desirable thioesterase activity profiles for plant genetic engineering applications. |