President’s Research Scholarship: Transition States of Dihydrofolate Reductase in Catalysis and Drug Design

Cardiff University
School of Chemistry

President’s Research Scholarship
The following funded postgraduate position is available in the group of Prof Rudolf Allemann:

Drug-resistant infections cost the UK billions of pounds, while drug-resistant variants of diseases such as malaria are global health problems. Equally serious is the problem of resistance to anticancer drugs.

Our laboratory has studied dihydrofolate reductases (DHFR) for many years in pursuit of a deeper understanding of the fundamental mechanisms that control enzyme action. DHFR catalyses conversion of dihydrofolate to tetrahydrofolate, which in turn is required for synthesis of DNA and a number of amino acids. DHFR is therefore an important biosynthetic enzyme and a validated target for agents such as the antibacterial trimethoprim, the antimalarial pyrimethamine or methotrexate, a clinically highly successful anticancer drug.

Enzymes catalyse chemical reactions by stabilising their transition states, and as a result transition state analogues have been used as inhibitors of enzymes like DHFR. We will use highly sensitive isotope effect methods in combination with computational techniques to create a map of the transition state of the DHFR catalysed reaction, which will be used to inform the design of transition state analogues that act as novel DHFR inhibitors with anticancer and antiinfective activities.
Isotope effect methods typically require introduction of isotopic labels at specific sites in the reactant molecules. We have initiated work to incorporate these labels using both synthetic and biosynthetic methods with promising preliminary results.

Two DHFRs will be studied: DHFR from E. coli, which we have studied extensively, will act as a model for bacterial DHFRs, and human DHFR. Comparing these DHFRs will allow development of selective antibacterial and anticancer compounds by exploiting transition state differences. Using knowledge of the inter-atomic distances and electrostatics gained from the isotope effect studies, molecules closely approximating the transition state will be designed, synthesised and assayed for inhibition, first in vitro to assess binding and the degree of selectivity for bacterial vs mammalian DHFRs, and later in vivo against pathogenic bacterial strains or human cancer/normal cell lines to assess any therapeutic advantage. Isotope effect studies will be expanded to clinically relevant bacterial DHFRs from S. aureus and M. tuberculosis, and the bifunctional DHFR-thymidylate synthase from P. falciparum. Compounds retaining significant affinity for human DHFR will be investigated as candidate anticancer agents using the HT29 colon carcinoma cell line.

The information obtained will allow for the first time a rational approach to the design and synthesis of novel DHFR inhibitors with clinical potential, addressing the rise in resistance to antibiotics and failure of anticancer agents - with significant potential for IP and exploitation.

If you are interested and highly motivated to engage in research work in a multidisciplinary group performing research at the interface between the physical and life sciences, we would like to hear from you. The Scholarship will be of interest to the highest quality candidates – those eligible for funding as President Scholars will have a first-class honours degree, or a 2.1 plus a postgraduate Masters degree (or their equivalents). These positions are available from October 2013 and open to EU and EEA students.

For further information about this and other positions see: http://www.cardiff.ac.uk/chemy/staffinfo/allemann/. To apply send your full CV and the contact details of at least 2 professional referees to Prof RK Allemann ([Email Address Removed]). Informal enquiries are welcome.