Suppression of p53 response by targeting p53-Mediator binding with a stapled peptide
Benjamin L. Allen,
Kim Quach,
Taylor Jones,
Cecilia B. Levandowski,
Christopher C. Ebmeier,
Jonathan D. Rubin,
Timothy Read,
Robin D. Dowell,
Alanna Schepartz,
Dylan J. Taatjes
Affiliations
Benjamin L. Allen
Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
Kim Quach
Department of Chemistry, Yale University, New Haven, CT 06520, USA
Taylor Jones
Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
Cecilia B. Levandowski
Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
Christopher C. Ebmeier
Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
Jonathan D. Rubin
Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
Timothy Read
Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA; Department of Medicine, Division of Genetics, Brigham & Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
Robin D. Dowell
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80303, USA; BioFrontiers Institute, University of Colorado, Boulder, CO 80303, USA
Alanna Schepartz
Department of Chemistry, Yale University, New Haven, CT 06520, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Department of Chemistry, University of California, Berkeley, CA 94720, USA; Corresponding author
Dylan J. Taatjes
Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA; Corresponding author
Summary: DNA-binding transcription factors (TFs) remain challenging to target with molecular probes. Many TFs function in part through interaction with Mediator, a 26-subunit complex that controls RNA polymerase II activity genome-wide. We sought to block p53 function by disrupting the p53-Mediator interaction. Through rational design and activity-based screening, we characterize a stapled peptide, with functional mimics of both p53 activation domains, that blocks p53-Mediator binding and selectively inhibits p53-dependent transcription in human cells; importantly, this “bivalent” peptide has negligible impact, genome-wide, on non-p53 target genes. Our proof-of-concept strategy circumvents the TF entirely and targets the TF-Mediator interface instead, with desired functional outcomes (i.e., selective inhibition of p53 activation). Furthermore, these results demonstrate that TF activation domains represent viable starting points for Mediator-targeting molecular probes, as an alternative to large compound libraries. Different TFs bind Mediator through different subunits, suggesting this strategy could be broadly applied to selectively alter gene expression programs.
