Abstract
Sumoylation is a post-translational modification which alters protein function, activity and subcellular localization. Covalent SUMO conjugation requires an E1/E2/E3 enzyme cascade similar to the ubiquitin-conjugating cascade. In most cases, the target proteins interact with both SUMO and E2 enzyme. Although sumoylation is known to be involved in various cellular processes, few SUMO-targeted proteins are reported in plants. In order to identify SUMO-targeted proteins, we performed the yeast two-hybrid screening using E2 enzyme, AtSCE1a, which is encoded by the only one gene in Arabidopsis. Three candidate proteins were isolated through the screening, including At2g20310, which is a plant-specific protein of unknown function. At2g20310 and its paralogous protein, At4g28690, interact with AtSUMO1, 2, and 3, respectively. Furthermore, sumoylation of both proteins were confirmed by in vitro and in vivo symoylation assays. At2g20310-GFP fusion protein is localized at the nucleus in root tissue. The functional analysis of these genes is currently in progress.
