Variations in protein structure at the level of amino acid sequence and modifications allow for the biological complexity observed in living organisms; a complexity that far exceeds that of the approximately 20,000 genes in the human genome that encode for proteins. Post-translational modifications (PTMs) add to the diversity of the proteome through the generation of new and different proteoforms. Amongst the known PTMs, proteolytic cleavage is an irreversible modification performed by proteases enzymes characterized by the highly precise cleavage of a protein into two or more smaller fragments¹. These new fragments can be stable in vivo and can exhibit altered biological activity, location, and interactions compared with their precursor protein. However, the mechanisms by which these processes are regulated remain largely mysterious.

An example of proteolytically processed proteins are the members of the Ubiquitin-like domain (UBL) fusion protein family². These undergo proteolytic cleavage as a mean to regulate their stability and physiological role³. We have recently discovered that the generated fragments can be further modified by installation of unprecedented PTMs, a mechanism we refer to as “Cleave-to-modify” (Figure 1). However, not much is known about Ubiquitin-like domain (UBL) fusion proteins, the protease enzymes involved in their processing and the biological events and modifications that are actioned as a result.

This project aims to identify novel substrateis and pathways regulated by the “cleave-to-modify” mechanism and link these discoveries to a cellular function. What makes this project especially exciting is its potential to reveal unprecedented fundamental pathway responsible for regulation of homeostasis, the disruption of which causes disease.

By uncovering the role and extent of this unprecedented mechanism, the proposed project will transform our understanding of protein processing and modification and, consequently, reveal new potential targets for pharmacological intervention.

This project takes advantage of a recently developed toolkit to study the ubiquitin-like-fusion protein system. Students interested in the opportunity to learn and employ a wide array of scientific techniques are strongly encouraged to apply since the project merges several disciplines, including method development, state-of-the-art mass spectrometry, cell biology, biophysics, and biochemistry. The student will have a unique opportunity to work at the bench alongside their supervisor.

References

1 Lange, P. F. & Overall, C. M. in Current Opinion in Chemical Biology Vol. 17 73-82 (Elsevier Ltd, 2013).

2 Kerscher, O., Felberbaum, R. & Hochstrasser, M. in Annu. Rev. Cell Dev. Biol Vol. 22 159-180 (2006).

3 Thakran, P. et al. in The EMBO Journal Vol. 37 89-101 (John Wiley & Sons, Ltd, 2018).