SUMO in the regulation of DNA repair and transcription at nuclear pores.

Two related post-translational modifications, the covalent linkage of Ubiquitin and the Small Ubiquitin-related MOdifier (SUMO) to lysine residues, play key roles in the regulation of both DNA repair pathway choice and transcription. Whereas ubiquitination is generally associated with protein degradation, the impact of sumoylation has been more mysterious. Sumoylation effects are largely mediated by the subnuclear localization of its targets, particularly in response to DNA damage. This is governed in part by the concentration of SUMO protease at nuclear pores (1,2). We review here the roles of sumoylation in determining subnuclear locus positioning relative to the nuclear envelope and the nuclear envelope to facilitate repair and to regulate transcription.