Discovery and Characterisation of Undefined Ubiquitin and Ubiquitin-like E3 Ligases

Modification of substrates with the small protein ubiquitin (Ub) regulates virtually all aspects of the cell. Additionally, modification with ubiquitin- like proteins (Ubls) has been implicated with important processes such innate antiviral immunity and cancer progression. E3 ligase enzymes (E3s) select specific substrates for modification and have great therapeutic importance. We have shown that novel E3s with unique mechanisms and unanticipated substrate biology remain to be discovered. Furthermore, to decipher the cellular functions of the growing complement of E3s in health and disease, a general and quantitative approach for measuring cellular E3 activity is urgently needed. In aim 1 of this proposal I will discover novel ubiquitin E3 machineries and establish their cellular functions. In Aim 2, newly discovered E3s will be carefully selected for structural characterisation and their catalytic mechanisms will be delineated at an atomic level. In Aim 3 I will develop chemical biological probes for Ubls allowing me to discover their missing E3s and gain insights into their cellular roles. In Aim 4 I will develop urgently needed global and quantitative technology that will not only expedite the study of E3s, but also accelerate the development of next generation medicines that modulate their activity.