A Comprehensive Analysis of Components in SUMO Pathway

SUMOylation is an essential post-translational modification that mediates in many biological processes including localisation, stability, or function. To date, the small ubiquitin-like modifier (SUMO) is present in all recorded eukaryotes and is the only ubiquitin-like modifier (Ubl) known to have multiple paralogs in humans. Little is known of SUMO and its machinery components from an evolutionary perspective. My aim is to investigate the origins and evolution of the SUMOylation pathway. The SUMO pathway enzymatic cascade catalyses post- translational modifications during the process of SUMOylation, a process where SUMO protein is added to substrate. We have evaluated SUMO, its heterodimeric E1 activating enzyme and E2 conjugating enzyme. This study suggests that diversification of SUMO homologs occurs in higher eukaryotes including metazoans and higher plants. Diversification of the E1 activating subunit (SAE1) was limited to higher plants. The catalytic subunit SAE2 of the E1 activating enzyme showed little expansion across the eukaryotic tree; and only a species-specific expansion of the E2. Our data highlights the conservation of SUMO and its potential presence within the last eukaryotic common ancestor.