Seminar with Professor Elizabeth Gillam – University of Copenhagen

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Seminar with Professor Elizabeth Gillam

On 5 September Prof. Elizabeth Gillam from School of Chemistry and Molecular Biosciences & Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia will give a seminar.

Looking to the past to evolve enzymes for the future: thermostable yet promiscuous cytochrome P450 enzymes for synthetic biology

Cytochrome P450 enzymes are ancient haemoproteins that have attracted intense interest for synthetic biology and biotechnology, since they can interact with, and introduce modifications into, a diverse variety of chemical substrates in a regio- and stereo-selective manner.

They have evolved to fulfill innumerable physiological roles including the biosynthesis of antibiotics and secondary metabolites and the clearance of xenobiotics such as drugs.  By catalysing the monooxygenation of unactivated C-H bonds, a reaction that is difficult to achieve by purely chemical means, P450s can effect hydroxylations, dealkylations, epoxidations, and ring rearrangements. However their industrial application has been limited to date due to the relative instability of the naturally occurring enzymes.  

We have reconstructed the evolutionary ancestors of the four animal P450 families involved in xenobiotic metabolism, and shown that they exhibit both broad substrate promiscuity and high thermostability, surviving temperatures up to ~ 66ºC, an increase of ~ 30ºC over their extant descendants.

Expression yield and solvent tolerance were also improved, translating into a significant improvement in product yield in incubations conducted under industrially relevant conditions. Limited site-saturation mutagenesis of the CYP3 ancestor generated mutants with even higher stability and diverse catalytic profiles.  

These results challenge the expectation that thermostability reduces flexibility in P450s, and extend our understanding of the evolution of the P450 fold. Stabilization of P450s to temperature should facilitate the wider implementation of these enzymes as biocatalysts in industrial processes and in other synthetic biology applications.