SUMOylation of chromosomal protein HMGN2 (HMG-17) alters its interaction with nucleosomes

Abstract

The high mobility group 17 (HMGN2) is a small and uniquitous non-histone protein which has many functions in a variety of cellular processes, such as architectural element, transcription regulation and DNA repair. In addition, it may have other functions such as antimicrobial activity, homing to special cells and cytokine release. Although the biochemical properties of HMGN2 protein are regulated by acetylation and phosphorylation, it is unknown whether HMGN2 activity can also be regulated by SUMOylation. In the present study, it was showed for the first time that HMGN2 is modified by the covalent attachment of small ubiquitin-related modifier 1 (SUMO1) and the major SUMOylation sites was identified, which locate within the HMGN2 nucleosome binding domain. SENP1 can desumoylate SUMOylated HMGN2 and PIAS1 plays as an E3 ligase in HMGN2 SUMOylation. Finally, using SUMO1-conjugated HMGN2 which was prepared from bacteria, it was demonstrated that SUMOylated HMGN2 decreases the binding ability to nucleosome core particles (NCPs) comparing to its unmodified form. These observations potentially provide new perspectives for a better understanding of the functions of HMGN2.