Substrate controlled divergence in polyketide synthase catalysis.

Area of Science:

• Biochemistry
• Synthetic Biology
• Enzymology

Background:

• Polyketide synthases (PKSs) are crucial enzymes in natural product biosynthesis.
• Characterizing PKSs traditionally uses synthetic N-acetylcysteamine thioesters.
• Controlling PKS catalytic cycles via substrate engineering is underexplored.

Purpose of the Study:

• To investigate substrate engineering for controlling the catalytic outcome of PKS modules.
• To examine the effect of alternatively activated native hexaketide substrates on PikAIV catalysis.

Main Methods:

• Utilized a series of alternatively activated native hexaketide substrates.
• Examined the catalytic outcome of PikAIV, a PKS module from the pikromycin pathway.
• Analyzed product formation based on substrate modification.

Main Results:

• Demonstrated selective control over PKS catalysis using engineered substrates.
• Achieved greater than 10:1 selectivity for either full module catalysis (14-membered macrolactone) or direct cyclization (12-membered ring).
• Showcased substrate engineering as a viable strategy for PKS functional studies.

Conclusions:

• Substrate engineering offers a powerful tool to direct PKS catalytic pathways.
• Modified hexaketide esters enable precise control over product formation in PKS biocatalysis.
• This approach advances the functional understanding and application of PKS enzymes.