Cereblon neo-substrate binding mimics the recognition of the cyclic imide degron

• Published in: Biochemical and biophysical research communications 2023-02, Vol.646, p.30-35
• Main Authors: Heim, Christopher, Spring, Anna-Katharina, Kirchgäßner, Sören, Schwarzer, Dirk, Hartmann, Marcus D.
• Format: Article
• Language: English
• Subjects: Aminoglutarimide degron; Aspartimide degron; Cullin-RING ubiquitin ligase; Immunomodulating Agents; Peptide Hydrolases - metabolism; Protein chain break; Protein damage; Proteolysis; Ubiquitin-proteasome system; Ubiquitin-Protein Ligases - metabolism; Ubiquitination
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2023.01.051

In targeted protein degradation, immunomodulatory drugs (IMiDs) or cereblon (CRBN) E3 ligase modulatory drugs (CELMoDs) recruit neo-substrate proteins to the E3 ubiquitin ligase receptor CRBN for ubiquitination and subsequent proteasomal degradation. While the structural basis of this mechanism is generally understood, we have only recently described the recognition mode of the natural CRBN degron. In this communication, we reveal that the IMiD- or CELMoD-mediated binding of neo-substrates closely mimics the recognition of natural degrons. In crystal structures, we identify a conserved binding mode for natural degron peptides with an elaborate hydrogen bonding network involving the backbone of each of the six C-terminal degron residues, without the involvement of side chains. In a structural comparison, we show that neo-substrates recruited by IMiDs or CELMoDs emulate every single hydrogen bond of this network and thereby explain the origins of the largely sequence-independent recognition of neo-substrates. Our results imply that the V388I substitution in CRBN does not impair natural degron recognition and complete the structural basis for the rational design of CRBN effectors. [Display omitted] •C-terminal cyclic imide degrons share a common sequence-independent binding mode.•Neo-substrate beta hairpins mimic the hydrogen bonding pattern of natural degrons.•The i - > i+4 H-bond in neo-substrate beta hairpins resembles that in degron peptides.•The V388I substitution impairs binding of neo-substrates but not of natural degrons.