Item

Abstract

The modular organization of the type I polyketide synthases (PKSs) would seem propitious for rational engineering of desirable analogous. However, despite decades of efforts, such experiments remain largely inefficient. Here, we combine multiple, state-of-the-art approaches to reprogram the stambomycin PKS by deleting seven internal modules. One system produces the target 37-membered mini-stambomycin metabolites - a reduction in chain length of 14 carbons relative to the 51-membered parental compounds - but also substantial quantities of shunt metabolites. Our data also support an unprecedented off-loading mechanism of such stalled intermediates involving the C-terminal thioesterase domain of the PKS. The mini-stambomycin yields are reduced relative to wild type, likely reflecting the poor tolerance of the modules downstream of the modified interfaces to the non-native substrates. Overall, we identify factors contributing to the productivity of engineered whole assembly lines, but our findings also highlight the need for further research to increase production titers.
Genetic engineering of the type I polyketide synthases (PKSs) to produce desirable analogous remains largely inefficient. Here, the authors leverage multiple approaches to delete seven internal modules from the stambomycin PKS and generate 37-membered mini-stambomycin macrolactones.