Genomic Maintenance & Repair

Monday, October 17, 2005 3:00 PM-5:00 PM Exhibit Hall

(PP366) Sumoylation of human Rad52 is critical in its protein stability.

Liu, Jingmei1, Wray, Justin*,1, Shen, Zhiyuan, 1 Dept. of Molecular Genetics and Microbiology, Albuquerque, NM, USA

ABSTRACT- Sumoylation is a post-translational protein modification process that conjugates an ubiquitin-like protein (UBL1 or SUMO1) to a variety of substrates. It facilitates the in vivo dynamic changes of protein complexes. The mammalian RAD52 protein redistributes to form nuclear foci in response to DNA damage and replication block, and plays an essential role in homologous recombination. It has been previously reported that the human RAD52 protein interacts with SUMO1 and its conjugating enzyme UBC9. Here report, we show that human RAD52 is sumoylated at a lysine residue that is highly conserved among higher eukaryotic RAD52 and RAD59 proteins. The sumoylation site in RAD52 protein family defines a new motif for sumoylation. Sumoylation defect RAD52 mutant is unstable and inefficient to form nuclear foci in response to DNA damage. In addition, a mutant RAD52 retained in cytoplasm is unable to be sumoylated. These data suggest that sumoylation of RAD52 occurs in the nucleus, and plays a significant role in stabilizing the protein and regulating the dynamics of RAD52 protein complex in vivo.

Key words: RAD52, Sumoylation, SUMO1, UBL1

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2005 RRS