Genetically Encoded Biosensor for Detection of Polyketide Synthase Extender Units in Escherichia coli

Our latest paper in ACS Synthetic Biology describes the first genetically-encoded biosensor for detection of polyketide synthase extender units in cells. Because the biosensor is genetically encoded, the cell makes all of the necessary components and the entire system can be subjected to directed evolution. A biosensor for detection of various acyl-CoA’s will help synthetic biology approaches for sustainable production of natural products in microbes.


Substrate promiscuity of isopentenyl phosphate kinase

Isoprenoids are a large class of natural products with wide‐ranging applications. Synthetic biology approaches to the manufacture of isoprenoids and their new‐to‐nature derivatives are limited due to the provision in Nature of just two hemiterpene building blocks for isoprenoid biosynthesis. To address this limitation, artificial chemo‐enzymatic pathways such as the alcohol‐dependent hemiterpene pathway (ADH) serve to leverage consecutive kinases to convert exogenous alcohols to pyrophosphates that could be coupled to downstream isoprenoid biosynthesis. To be successful, each kinase in this pathway should be permissive of a broad range of substrates. For the first time, we have probed the promiscuity of the second enzyme in the ADH pathway, isopentenyl phosphate kinase from Thermoplasma acidophilum, towards a broad range of acceptor monophosphates. Subsequently, we evaluate the suitability of this enzyme to provide non‐natural pyrophosphates and provide a critical first step in characterizing the rate limiting steps in the artificial ADH pathway.

See the publication at ChemBioChem!

New paper in the J Am Chem Soc!

In a new paper in JACS by recent graduate Edward Kalkreuter (now a postdoc at Scripps, Florida), the synthetic scope of a polyketide synthase was expanded by engineering the incorporation of consecutive extender unit substrates. Unexpected downstream bottlenecks were also revealed, identifying new targets for enzyme engineering.

New publication!

Recently minted PhD Samantha Meiser Carpenter (now at BASF) describes the substrate promiscuity of a unique trans-acyltransferase from Zwittermicin biosynthesis in ACS Chemical Biology. Her work expands what is known about these ACP-dependent enzymes and suggests new strategies to diversify antibiotics.

Contributions to two RSC books!


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Check out Chapter 11 of “Chemical and Biological Synthesis: Enabling Approaches for Understanding Biology”, for a summary of precursor-directed biosynthesis by Edward Kalkreuter and Samantha Carpenter! In addition, Christian Kasey authored Chapter 8 of the book “Modern Biocatalysis: Advances Towards … Continue reading