Professor Catherine Day

Head of Department
  • Biochemistry Department
  • School of Biomedical Sciences
  • University of Otago
  • P.O. Box 56
  • 710 Cumberland St
  • Dunedin 9054 , New Zealand
  • Tel.: 64 3 479-7871 , +64 3 479-7864 (HOD office)
  • Fax: 64 3 479-7866


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
For information about scholarships for postgraduate students go to the University of Otago's website


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


  • Josh Wright
  • 2015, Department of Biochemistry Best Student Publication Award
  • Josh Wright
  • 2014, Otago School of Medical Sciences Postgraduate Symposium Poster prize, Runner up
  • Catherine Day
  • 2014, Elected as Fellow of the Royal Society of New Zealand
  • Josh Wright
  • 2013, Otago School of Medical Sciences Postgraduate Symposium Poster Prize
  • Jessica Craig
  • 2013, Best Prestigious Summer Scholarship Report
  • Professor Catherine Day
  • 2010, Otago School of Medical Sciences Distinguished Researcher of the Year
  • Associate Professor Catherine Day
  • 2010, New Zealand Society for Biochemistry and Molecular Biology Life Technologies Award
  • This is the premier award of the Society and is awarded annually for outstanding scientific research.

Selected Publications

Joshua D Wright, Peter D Mace, and Catherine L Day., Noncovalent Ubiquitin Interactions Regulate the Catalytic Activity of Ubiquitin Writers., Trends Biochem Sci 2016., Link »

Martina Foglizzo, Adam J Middleton, and Catherine L Day., Structure and Function of the RING Domains of RNF20 and RNF40, Dimeric E3 Ligases that Monoubiquitylate Histone H2B., J Mol Biol 2016., Link »

Joshua D Wright, Peter D Mace, and Catherine L Day., Secondary ubiquitin-RING docking enhances Arkadia and Ark2C E3 ligase activity., Nat Struct Mol Biol 2015., Link »

Adam J Middleton and Catherine L Day., The molecular basis of lysine 48 ubiquitin chain synthesis by Ube2K., Sci Rep 2015 vol. 5 p. 16793., Link »

Rhesa Budhidarmo and Catherine L Day, The Ubiquitin-associated Domain of Cellular Inhibitor of Apoptosis Proteins Facilitates Ubiquitylation., The Journal of Biological Chemistry 2014 vol. 289 (37) pp. 25721-25736, Link »

Adam J Middleton, Rhesa Budhidarmo, and Catherine L Day, Use of E2~ubiquitin conjugates for the characterization of ubiquitin transfer by RING E3 ligases such as the inhibitor of apoptosis proteins., Methods in Enzymology 2013 vol. 545 pp. 243-263, Link »

Frances-Rose Schumacher, Georgina Wilson, and Catherine L Day, The N-Terminal Extension of UBE2E Ubiquitin-Conjugating Enzymes Limits Chain Assembly., Journal of Molecular Biology 2013, Link »

Yoshio Nakatani, Torsten Kleffmann, Katrin Linke, Stephen M. Condon, Mark G Hinds, and Catherine L Day, Regulation of ubiquitin transfer by XIAP, a dimeric RING E3 ligase., The Biochemical Journal 2013 vol. 450 (3) pp. 629-638, Link »

Rhesa Budhidarmo, Yoshio Nakatani, and Catherine L Day, RINGs hold the key to ubiquitin transfer., Trends In Biochemical Sciences 2012 vol. 37 (2) pp. 58-65, Link »

R Feltham, B Bettjeman, R Budhidarmo, P D Mace, S Shirley, S.M. Condon, S.K. Chunduru, M.A. McKinlay, D L Vaux, J Silke, and C L Day, Smac mimetics activate the E3 ligase activity of cIAP1 protein by promoting RING domain dimerization, The Journal of Biological Chemistry 2011 vol. 286 (19) pp. 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.

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.