Biochemistry

Research: 

Many key events within cells are regulated by the appropriate interaction of two proteins. Understanding the molecular basis of protein-protein interactions is central to elucidation of these cellular processes and can lead to the development of new or improved therapeutic compounds.  

I am interested in understanding how a number of proteins involved in apoptosis interact, and how this knowledge can be exploited for the development of improved anti-cancer compounds. Most recently, we have focused on characterisation of processes that result in attachment of ubiquitin to proteins because our analysis of the Inhibitor of Apoptosis (IAP) proteins showed that ubiquitin is important for their regulation. 

Modification of proteins by ubiquitin relies on an enzyme cascade (see figure above) that culminates in an E3 protein. E3-ligases that possess a RING domain mediate transfer of ubiquitin from the E2 to the substrate protein that is recruited by the E3. Although substrate ubiquitylation is routinely observed, a detailed understanding of ubiquitin transfer remains elusive. Research in my laboratory has focused on characterisation of the ubiquitin E3-ligase activity of proteins that have a C-terminal RING domain. Our goal is to understand how interaction of the RING domain with the E2 (see figure below) promotes transfer of ubiquitin from the E2 to the substrate.  It is hoped that a molecular understanding will allow manipulation of this process by therapeutic compounds. 

Current projects in my laboratory are focused on understanding the mechanisms that control ubiquitin transfer, including the role of RING dimerisation, the mechanisms by which the E2 influences the ubiquitin modification and the role of ubiquitin binding domains. Collaboration with other research groups is an important component of these projects.

Positions available

Enquires about projects from prospective graduate students and postdoctoral fellows are welcome and should be sent to catherine.day@otago.ac.nz

For information about scholarships for postgraduate students go to the University of Otago's website http://www.otago.ac.nz/postgraduate/index.html

Funding

Research in my laboratory is funded by the Health Research Counci l
of New Zealand, the Marsden Fund, Lottery Health 
NZ and University of Otago Research Grants.

Selected Recent Publications

Budhidarmo, R., Nakatani, Y. and Day, C.L. (2011) RINGs hold the key to ubiquitin transfer. Trends in Biochemical Sciences 

Feltham, R., Bettjeman, B., Budhidarmo, R., Mace, P.D., Shirley, S., Condon, S.M., Chunduru, S.K., McKinlay, M.A., Vaux, D.L., Silke, J. & Day, C.L. (2011) Smac-mimetics activate the E3 ligase activity of cIAP1 by promoting RING dimerisation. J. Biol. Chem. 286, 17015-17028

Liew. C.W., Sun, S., Hunter, T. & Day, C.L. (2010) RING domain dimerization is essential for RNF4 function. Biochem. J. 431, 23-29.

Mace, P.D., Smits, C., Vaux, D.L., Silke, J. & Day, C.L. (2010) Asymmetric recruitment of cIAPs by TRAF2. J. Mol. Biol. 400, 8-15.

Mace, P.D., Shirley, S. & Day, C.L. (2010) Assembling the Building Blocks: Structure and Function of Inhibitor of Apoptosis Proteins. Cell Death Differ. 17, 46-53.

Risk, J.M., Macknight, R.C. & Day, C.L. (2008) FCA does not bind abscisic acid. Nature 456 (7223), E5-E6.

Day, C. L., Smits, C., Fan, F. C., Lee, E. F., Fairlie, W. D. and Hinds, M. G. (2008) Structure of the BH3-domains from the p53 inducible BH3-only proteins Noxa and Puma in complex with Mcl-1. J. Mol. Biol. 380, 958-971.

Smits, C., Czabotar, P. E., Hinds, M.G. and Day, C. L. (2008) Structural plasticity underpins promiscuous binding of the pro-survival protein A1. Structure 16, 818-829. 

Mace, P.D., Linke, K., Feltham, R., Schumacher, F-R, Smith, C.A., Vaux, D.L., Silke, J. & Day, C.L. (2008) Structures of the cIAP2 RING Domain Reveal Conformational Changes Associated with Ubiquitin-conjugating Enzyme (E2) Recruitment. J. Biol Chem. 283, 31633-40.

Linke, K., Mace, P., Smith, C. A., Vaux, D. L., Silke, J. and Day, C. L. (2008) Structure of the MDM2/MDMX RING domain heterodimer reveals dimerization is required for their ubiquitylation in trans. Cell Death Differ. 15, 841-848.        

Hinds, M. G., Smits, C., Fredericks-Short, R., Risk, J. M., Bailey, M., Huang, D. C. & Day, C. L. (2007) Bim, Bad and Bmf: intrinsically unstructured BH3-only proteins that undergo a localized conformational change upon binding to pro-survival Bcl-2 targets. Cell Death Differ. 14, 128-136.