초록
<P><B>ABSTRACT</B></P><P>The native yeast type I fatty acid synthase (FAS) is a complex, rigid enzyme, and challenging to engineer for the production of medium‐ or short‐chain fatty acids. Introduction of a type II FAS is a promising alternative as it allows expression control for each discrete enzyme and the addition of heterologous thioesterases. In this study, the native <I>Saccharomyces cerevisiae</I> FAS was functionally replaced by the <I>Escherichia coli</I> type II FAS (eFAS) system. The <I>E. coli acpS</I> + <I>acpP</I> (together), <I>fabB</I>, <I>fabD</I>, <I>fabG</I>, <I>fabH</I>, <I>fabI</I>, <I>fabZ</I>, and <I>tesA</I> were expressed in individual <I>S. cerevisiae</I> strains, and enzyme activity was confirmed by in vitro activity assays. Eight genes were then integrated into the yeast genome, while <I>tesA</I> or an alternate thioesterase gene, <I>fatB</I> from <I>Ricinus communis</I> or TEII from <I>Rattus novergicus</I>, was expressed from a multi‐copy plasmid. Native FAS activity was eliminated by knocking out the yeast <I>FAS2</I> gene. The strains expressing only the eFAS as de novo fatty acid source grew without fatty acid supplementation demonstrating that this type II FAS is able to functionally replace the native yeast FAS. The engineered strain expressing the <I>R. communis fatB</I> thioesterase increased total fatty acid titer 1.7‐fold and shifted the fatty acid profile towards C<SUB>14</SUB> production, increasing it from <1% in the native strain to more than 30% of total fatty acids, and reducing C<SUB>18</SUB> production from 39% to 8%. Biotechnol. Bioeng. 2015;112: 2618–2623. © 2015 Wiley Periodicals, Inc.</P>