This research demonstrates that a short peptide, composed of residues 24-55 of ZNF451, is sufficient to induce SUMOylation of target proteins, both in vitro and in human cells. Increased SUMOylation of the transcription factor p53 via fusion with the ZNF451 peptide inhibits its transcriptional activity, providing a proof of principle that targeted SUMOylation can be used to modulate the activity of targeted transcription factors.