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Contact Details

Phone
+64 3 479 7871
Email
catherine.day@otago.ac.nz

University Links

Position
Professor
Department
Department of Biochemistry
Qualifications
BSc(Hons) PhD(Massey)
Research summary
Molecular basis of signalling.

Research

Fine tuning signalling

Proteins regulate all cellular processes, with their activities often fine tuned by modification with other molecules after they have been made. One important modification that regulates protein function is ubiquitin. Aberrant addition of ubiquitin results in a range of diseases, including cancer and autoimmune diseases.

My research group is interested in understanding how the addition of ubiquitin regulates protein function. Our goal is to discover how the attachment of ubiquitin to proteins is regulated, and how this modification alters protein function.

We have focused on the RING E3 ligases, the proteins that specify the targets for ubiquitin addition. Using structural, biochemical and biophysical approaches we have discovered important regulatory mechanisms that provide insight into how information in cells is transmitted.

Current projects in my laboratory focus on:

Understanding how E3 ligases promote the attachment of ubiquitin. We have a number of projects aimed at elucidating how RING-E3 ligases are regulated. For example we recently showed that TRAF6, a RING-E3, is regulated by RING dimerisation and that heterodimers can form. This suggests an unexpected level of signalling complexity.

Revealing how ubiquitin chains are assembled. The ubiquitylation machinery contains many ubiquitin-binding sites. For example Ark2C is activated by ubiquitin binding to the RING domain (below). We have several projects aimed at understanding how ubiquitin-binding by the E2/E3 ubiquiitn writing machines modulates assembly of ubiquitin chains.

We are always keen to collaborate on projects aimed at understanding how ubiquitin is regulated.

Positions available

Enquiries about projects from prospective graduate students 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 website otago.ac.nz/postgraduate.

Funding

Funding for my research has been provided by the Marsden Fund (NZ), the Health Research Council of New Zealand, Lottery Health, Genesis Oncology and the University of Otago.

Publications

Middleton, A. J., & Day, C. L. (2025). RNF114, a RING E3 ligase that reads and extends the hybrid ADP-ribose-ubiquitin signal. EMBO Journal. Advance online publication. doi: 10.1038/s44318-025-00576-0 Journal - Research Other

Rossig, C., Paluda, A., Chen, R., Middleton, A. J., & Day, C. L. (2025). Arkadia and Ark2C promote substrate ubiquitylation with multiple E2 enzymes. Journal of Molecular Biology. Advance online publication. doi: 10.1016/j.jmb.2025.169259 Journal - Research Article

McAlpine, J. M. R. B., Zhu, G., Pudjihartono, N., Teyra, J., Currie, M. J., Tillett, Z. D., Dobson, R. C. J., … Day, C. L., & Middleton, A. J. (2024). Structural and biophysical characterisation of ubiquitin variants that inhibit the ubiquitin conjugating enzyme Ube2d2. FEBS Journal, 291, 5305-5321. doi: 10.1111/febs.17311 Journal - Research Article

Barzak, F. M., Lu, A., Geltzeiler, A. R., Ledgerwood, E. C., Chung, W. K., & Day, C. L. (2024). A novel RNF125 variant associated with Tenorio syndrome alters ubiquitin chain binding. Clinical Genetics, 105, 254-261. doi: 10.1111/cge.14457 Journal - Research Article

Middleton, A. J., Barzak, F. M., Fokkens, T. J., Nguyen, K., & Day, C. L. (2023). Zinc finger 1 of the RING E3 ligase, RNF125, interacts with the E2 to enhance ubiquitylation. Structure, 31(10), 1208-1219. doi: 10.1016/j.str.2023.07.007 Journal - Research Article

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