| 摘要 |
Methods of altering substrate specificity of plant acyl-ACP thioesterases, and engineered plant acyl-ACP thioesterases so produced are provided. The Cterminal 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. Of particular interest is a plant 18:1 thioesterase in which the relative 18:0 activity has been increased. Such FatA thioesterases find use for improved production of stearate in vegetable seed oils.
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