The SUMO cycle begins with free precursor SUMO undergoing maturation via a SUMO ULP protease—cleaving off the C-terminus exposing a diglycine motif. Mature SUMO is then activated by a hydrolyzed ATP molecule and a SUMO E1 enzyme—a heterodimer of AtSAE1a/b and AtSAE2 [21]. The activated SUMO is transferred from AtSAE2 to AtSCE1, an E2 conjugation enzyme—forming a SUMO-AtSCE1 thioester complex, which catalyzes the process of SUMOylation onto a target protein [29]. SUMO E3 ligases aid in the transfer of SUMO proteins from AtSCE1 onto the lysine residue of target proteins [25]. SUMO E4 is a further step in the SUMO cycle and promotes the formation of SUMO chains [34,35]. Finally, SUMO proteases cleave SUMO from target proteins via a process called deSUMOylation to create pools of free SUMO, therefore, making the process of SUMOylation reversible [2].