Professor Elizabeth Gillam

Professor

School of Chemistry and Molecular Biosciences
Faculty of Science
e.gillam@uq.edu.au
+61 7 336 51410

Overview

The molecular evolution of cytochrome P450 Enzymes: biological catalysts of unprecedented versatility.

Cytochrome P450 enzymes (CYPs, P450s) especially those responsible for drug metabolism in humans, are the unifying theme of the research in our lab. These fascinating enzymes are catalysts of exceptional versatility, and functional diversity. In humans they are principally responsible for the clearance of a practically unlimited variety of chemicals from the body, but are also critical in many important physiological processes. In other organisms (plants, animals, bacteria, fungi, almost everything!) they carry out an unprecedented range of functions, such as defense, chemical communication, neural development and even pigmentation. P450s are involved in the biosynthesis of an unequalled range of potent, biologically active natural products in microbes, plants and animals, including many antibiotics, plant and animal hormones, signalling molecules, toxins, flavours and fragrances. We are studying how P450s have evolved to deal with novel substrates by reconstructing ancestral precursors and evolutionary pathways, to answer such questions as how did the koala evolve to live on eucalyptus leaves, a toxic diet for most mammals.

The capabilities of P450s are only just coming to be fully recognized and structural studies on P450s should yield critical insights into how enzyme structure determines function. For example, recently we discovered that P450s are present within cells in the Fe(II) form, a finding that has led to a radical revision of the dogma concerning the P450 catalytic cycle, and has implications for the control of uncoupling of P450 activity in cells. Importantly, the biotechnological potential of P450s remains yet to be exploited. All of the specific research themes detailed below take advantage of our recognized expertise in the expression of recombinant human cytochrome P450 enzymes in bacteria. Our group is interested in finding out how P450s work and how they can be made to work better.

Artificial evolution of P450s for drug development and bioremediation: a way of exploring the sequence space and catalytic potential of P450s. The demonstrated catalytic diversity of P450 enzymes makes them the ideal starting material for engineering sophisticated chemical reagents to catalyse difficult chemical transformations. We are using artificial (or directed) evolution to engineer enzymes that are more efficient, robust and specialized than naturally occurring enzymes with the aim of selecting for properties that are commercially useful in the areas of drug discovery and development and bioremediation of pollutants in the environment. The approach we are using also allows us to explore the essential sequence and structural features that underpin all ~12000 known P450s so as to determine how they work.

Synthetic biology of enzymes for clean, green, solar-powered chemistry in drug development, bioremediation and biosensors. We have identified ancestral enzymes that are extremely thermostable compared to their modern counterparts, making them potentially very useful in industry, since they can withstand long incubations at elevated temperatures. They can be used as ‘off the shelf’ reagents to catalyse useful chemistry, such as in in drug discovery and development, fine chemicals synthesis, and cleaning up the environment. Working with drug companies, we are exploring how they can be best deployed in chemical processes and what structural features make them efficient, robust and specialized. We are also immobilizing P450s in virus-like-particles as ‘designer’ reagents that can be recovered from reactions and reused. To make such processes cheaper and more sustainable, we are using photosynthesis to power P450 reactions for clean, green biocatalysis in microalgae.

Biosketch:

After graduating from UQ with first class Honours in Biochemistry, Elizabeth took up a Royal Commission for the Exhibition of 1851 Overseas Scholarship to pursue doctoral work at Oxford University then undertook postdoctoral work at the Center in Molecular Toxicology and Department of Biochemistry at Vanderbilt University School of Medicine with Prof. F.P. Guengerich. She returned to UQ in 1993 to take up a position in Pharmacology and joined the School of Chemistry and Molecular Biosciences in 2009 as a Professor of Biochemistry.

Research Impacts

Our research is leading to the development of more sustainable, environmentally friendly, chemical processes to accelerate drug development and improve the safety of medicines. Our studies into the evolution of catalytic promiscuity in P450s reveal how organisms have evolved to deal with chemicals in the environment and provide insights as to how enzymes develop novel functions. More broadly, the methods that we have developed with colleagues at UQ and in industry for the ancestral reconstruction of P450s and their implementation as sophisticated biocatalysts in industry can be applied to the optimisation of other proteins and enzymes for biotechnological application.

Qualifications

  • Doctor of Philosophy, Oxf.
  • Bachelor of Science (Honours), The University of Queensland

Publications

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Supervision

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Available Projects

  • Strigolactones (SLs) are a class of plant hormones that control many traits important for agriculture including shoot and root architecture, nutrient uptake and responses to parasitic weeds. Parasitic weeds stimulated by plant-derived SLs are widespread in arable lands of many developing countries and have devastating impacts on food production. Application of synthetic SLs to infested soils would provide a way to clear arable land of parasitic weeds and greatly enhance food security in the third world. Biotechnological sources of natural or chemically modified SLs would also improve agricultural crop yield and reduce manual labour costs in horticultural industries. The overall objective of this project is to develop means for SL production in biofactories and to improve the potency of synthetic and/or biofactory/engineered SLs. We will do so by analysing the evolution of naturally occurring SL-synthesising enzymes and leveraging ancestral sequence reconstruction to engineer robust novel 'designer' enzymes with specific desired activities.

  • The diet of koalas is unique in comprising effectively 100% eucalyptus leaves, which contain a variety of potentially toxic terpenes. Cytochrome P450 enzymes are regarded as responsible for the metabolism of dietary and other environmental xenobiotics. Compared to other marsupials and mammals more generally, koalas show a dramatic expansion in the CYP2C subfamily of P450s so we hypothesise that the CYP2C forms in koalas have expanded to deal with the terpenes present in their diet and can oxidise these chemicals to facilitate their clearance from the koala’s circulation.

    We will test this hypothesis by synthesising and subcloning the CYP2C enzymes from koalas then expressing them in E. coli with the extant reductase accessory enzyme. The recombinant enzymes will be characterised for P450 yield then enzyme activity towards cineole and other terpenes as well as more typical CYP2C marker substrates will be assessed to explore their substrate specificity. If the hypothesis is proven to be correct (i.e. the extant koala CYP2C forms metabolise terpenes), selected ancestors of these CYP2C enzymes will be inferred, reconstructed and expressed to allow comparison with the extant forms to determine when the ability to metabolise eucalyptus terpenes evolved.

  • The ancestral P450s we have developed are extremely thermostable compared to modern enzymes, making them potentially very useful in industry, since they can withstand long incubations at elevated temperatures. They can be used as ‘off the shelf’ reagents to catalyse useful chemistry, such as in in drug discovery and development, fine chemicals synthesis, and cleaning up the environment. Working with drug companies, we are exploring how they can be best deployed in chemical processes and what structural features make them efficient, robust and specialized. We are also immobilizing P450s in virus-like-particles as ‘designer’ reagents that can be recovered from reactions and reused. To make such processes cheaper and more sustainable, we are using photosynthesis to power P450 reactions for clean, green biocatalysis in microalgae.

View all Available Projects

Publications

Book

  • Elizabeth M.J. Gillam, Janine N. Copp and David F. Ackerley eds. (2014). Directed Evolution Library Creation: methods and protocols. 2nd ed. Methods in Molecular Biology, New York, NY United States: Springer. doi: 10.1007/978-1-4939-1053-3

Book Chapter

  • Ross, Connie M., Foley, Gabriel, Boden, Mikael and Gillam, Elizabeth M. J. (2022). Using the Evolutionary History of Proteins to Engineer Insertion-Deletion Mutants from Robust, Ancestral Templates Using Graphical Representation of Ancestral Sequence Predictions (GRASP). Methods in Molecular Biology. (pp. 85-110) New York, NY: Humana Press Inc.. doi: 10.1007/978-1-0716-1826-4_6

  • Jackson, Colin J., Gillam, Elizabeth M.J. and Ollis, David L. (2020). Directed evolution of enzymes. Comprehensive Natural Products III. (pp. 654-673) Elsevier. doi: 10.1016/B978-008045382-8.00675-4

  • Zaugg, Julian, Gumulya, Yosephine, Gillam, Elizabeth M. J. and Bodén, Mikael (2014). Computational tools for directed evolution: a comparison of prospective and retrospective strategies. Directed evolution library creation: methods and protocols. (pp. 315-333) edited by Elizabeth M. J. Gillam, Janine N. Copp and David F. Ackerley. New York, NY, United States: Humana Press. doi: 10.1007/978-1-4939-1053-3_21

  • Gillam, Elizabeth M. J., Copp, Janine N. and Ackerley, David F. (2014). Preface. Directed evolution library creation: methods and protocols. (pp. v-vi) edited by Elizabeth M.J. Gillam, Janine N. Copp and David Ackerley. New York, NY United States: Humana Press.

  • Behrendorff, James B. Y. H., Johnston, Wayne A. and Gillam, Elizabeth M. J. (2013). DNA shuffling of cytochrome P450 enzymes. In Ian R. Phillips, Elizabeth A. Shepherd and Paul R. Ortiz de Montellano (Ed.), Cytochrome P450 protocols 3rd ed. (pp. 177-188) New York, NY, United States: Humana Press. doi:10.1007/978-1-62703-321-3_16

  • Johnston, Wayne A. and Gillam, Elizabeth M. J. (2013). Measurement of P450 difference spectra using intact cells. Cytochrome P450 protocols. (pp. 189-204) edited by Ian R. Phillips, Elizabeth A. Shepherd and Paul R. Ortiz de Montellano. New York, NY, United States: Humana Press. doi: 10.1007/978-1-62703-321-3_17

  • Jackson, Colin J., Gillam, Elizabeth M. J. and Ollis, David L. (2010). Directed evolution of enzymes. Comprehensive natural products II chemistry and biology. (pp. 723-749) edited by Lewis Mander and Hung-Wen Liu. Oxford, England, Unied Kingdom: Elsevier.

  • Gillam, E. M. J. and Hunter, D. J. B. (2007). Chemical Defence and Exploitation: Biotransformation of Xenobiotics by Cytochrome P450 Enzymes. Metal Ions in Life Sciences. (pp. 477-560) edited by Astrid Sigel, Helmut Sigel and Roland K. O. Sigel. West Sussex: John Wiley and sons. doi: 10.1002/9780470028155.ch15

Journal Article

Conference Publication

Other Outputs

Grants (Administered at UQ)

PhD and MPhil Supervision

Current Supervision

  • Doctor Philosophy — Principal Advisor

  • Doctor Philosophy — Principal Advisor

  • Doctor Philosophy — Principal Advisor

  • Doctor Philosophy — Principal Advisor

  • Doctor Philosophy — Principal Advisor

    Other advisors:

  • Doctor Philosophy — Associate Advisor

    Other advisors:

  • Doctor Philosophy — Associate Advisor

  • Doctor Philosophy — Associate Advisor

    Other advisors:

Completed Supervision

Possible Research Projects

Note for students: The possible research projects listed on this page may not be comprehensive or up to date. Always feel free to contact the staff for more information, and also with your own research ideas.

  • Strigolactones (SLs) are a class of plant hormones that control many traits important for agriculture including shoot and root architecture, nutrient uptake and responses to parasitic weeds. Parasitic weeds stimulated by plant-derived SLs are widespread in arable lands of many developing countries and have devastating impacts on food production. Application of synthetic SLs to infested soils would provide a way to clear arable land of parasitic weeds and greatly enhance food security in the third world. Biotechnological sources of natural or chemically modified SLs would also improve agricultural crop yield and reduce manual labour costs in horticultural industries. The overall objective of this project is to develop means for SL production in biofactories and to improve the potency of synthetic and/or biofactory/engineered SLs. We will do so by analysing the evolution of naturally occurring SL-synthesising enzymes and leveraging ancestral sequence reconstruction to engineer robust novel 'designer' enzymes with specific desired activities.

  • The diet of koalas is unique in comprising effectively 100% eucalyptus leaves, which contain a variety of potentially toxic terpenes. Cytochrome P450 enzymes are regarded as responsible for the metabolism of dietary and other environmental xenobiotics. Compared to other marsupials and mammals more generally, koalas show a dramatic expansion in the CYP2C subfamily of P450s so we hypothesise that the CYP2C forms in koalas have expanded to deal with the terpenes present in their diet and can oxidise these chemicals to facilitate their clearance from the koala’s circulation.

    We will test this hypothesis by synthesising and subcloning the CYP2C enzymes from koalas then expressing them in E. coli with the extant reductase accessory enzyme. The recombinant enzymes will be characterised for P450 yield then enzyme activity towards cineole and other terpenes as well as more typical CYP2C marker substrates will be assessed to explore their substrate specificity. If the hypothesis is proven to be correct (i.e. the extant koala CYP2C forms metabolise terpenes), selected ancestors of these CYP2C enzymes will be inferred, reconstructed and expressed to allow comparison with the extant forms to determine when the ability to metabolise eucalyptus terpenes evolved.

  • The ancestral P450s we have developed are extremely thermostable compared to modern enzymes, making them potentially very useful in industry, since they can withstand long incubations at elevated temperatures. They can be used as ‘off the shelf’ reagents to catalyse useful chemistry, such as in in drug discovery and development, fine chemicals synthesis, and cleaning up the environment. Working with drug companies, we are exploring how they can be best deployed in chemical processes and what structural features make them efficient, robust and specialized. We are also immobilizing P450s in virus-like-particles as ‘designer’ reagents that can be recovered from reactions and reused. To make such processes cheaper and more sustainable, we are using photosynthesis to power P450 reactions for clean, green biocatalysis in microalgae.

  • We are using directed evolution approaches, including ancestral sequence reconstruction, to engineer enzymes that are more efficient, robust and specialized than naturally occurring enzymes for application in drug discovery and development and cleaning up the environment. The approach we are using also allows us to explore the essential sequence and structural features that underpin all known P450s so as to determine how they work.

  • P450s metabolise ~ 95% of all drugs as well as innumerable environmental chemicals. This is an extraordinary range of substrates, many of which have not been present during evolution. We are studying how P450s have evolved to deal with such novel substrates by reconstructing ancestral precursors and evolutionary pathways