Biology subjects

Bonazzi, S.

Publications and source records attributed to Bonazzi, S..

4 recordsLinked to original sources

bioRxiv2024

Discovery of molecular glues that bind FKBP12 and novel targets using DNA-barcoded libraries

Molecular glues are small molecules that engage their target and presenter proteins cooperatively. FKBP12 molecular glues (FK506 and rapamycin) were discovered several decades ago and have been used clinically, but our understanding of the breadth of FKBP12 molecular glues and targets has yet to be fully revealed. To identify novel targets of FKBP12 molecular glues, we constructed and screened a multi-million-member non-macrocyclic FKBP12-ligand DNA-encoded library using 25 structurally distinct proteins. Synthesis and validation of selected hits in biophysical and cell-based assays confirm FKBP12-dependent molecular-glue recruitment to bromodomain-containing protein 9 (BRD9) and quinoid dihydropteridine reductase (QDPR). One glue showed no measurable binding to QDPR alone but had appreciable binding in the presence of FKBP12 using either purified proteins or intact cells. The sites of recruitment were characterized with mutational analysis, competition-based methods and X-ray crystallography. The results of this study confirm that FKBP12-binding DELs can yield novel molecular glues generating highly selective FKBP12-target protein interactions.

biophysics↗

bioRxiv2023

Rational screening for cooperativity in small-molecule inducers of protein-protein associations

The hallmark of a molecular glue is its ability to induce cooperative protein-protein interactions, leading to the formation of a ternary complex, despite weaker binding towards one or both individual proteins. Notably, the extent of cooperativity distinguishes molecular glues from bifunctional compounds, a second class of inducers of protein-protein interactions. However, apart from serendipitous discovery, there have been limited rational screening strategies for the high cooperativity exhibited by molecular glues. Here, we propose a binding-based screen of DNA-barcoded compounds on a target protein in the presence and absence of a presenter protein, using the "presenter ratio", the ratio of ternary enrichment to binary enrichment, as a predictive measure of cooperativity. Through this approach, we identified a range of cooperative, noncooperative, and uncooperative compounds in a single DNA-encoded library screen with bromodomain (BRD)9 and the VHL-elongin C-elongin B (VCB) complex. Our most cooperative hit compound, 13-7, exhibits micromolar binding affinity to BRD9 but nanomolar affinity for the ternary complex with BRD9 and VCB, with cooperativity comparable to classical molecular glues. This approach may enable the discovery of molecular glues for pre-selected proteins and thus facilitate the transition to a new paradigm of molecular therapeutics.

biophysics↗

bioRxiv2022

DNA-encoded library (DEL)-enabled discovery of proximity-inducing small molecules

Molecular glues and bifunctional compounds that induce protein-protein associations provide a powerful and general mechanism to modulate cell circuitry. We sought to develop a platform for the direct discovery of compounds able to induce association of any two pre-selected proteins, using the first bromodomain of BRD4 and the VHL-elongin C-elongin B (VCB) complex as a test system. Leveraging the screening power of DNA-encoded libraries (DELs), we synthesized [~]one million DNA-encoded compounds that possess a VHL-targeting fragment, a variety of connectors, and a diversity element generated by split- and-pool combinatorial chemistry. By screening our DEL against BRD4BD1 in the presence and absence of VCB, we could identify VHL-bound molecules that simultaneously bind BRD4. For highly barcode-enriched library members, ternary complex formation leading to BRD4 degradation was confirmed in cells. Furthermore, a ternary complex crystal structure was obtained for the most enriched library member. Our work provides a foundation for adapting DEL screening to the discovery of proximity-inducing small molecules. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=73 SRC="FIGDIR/small/512184v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@43f3c9org.highwire.dtl.DTLVardef@13a1f9eorg.highwire.dtl.DTLVardef@f1d751org.highwire.dtl.DTLVardef@16f3789_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2022

Diversity-oriented synthesis encoded by deoxyoligonucleotides

Diversity-oriented synthesis (DOS)is a powerful strategy to prepare molecules with underrepresented features in commercial screening collections, resulting in the elucidation of novel biological mechanisms. In parallel to the development of DOS, DNA-encoded libraries (DELs) have emerged as an effective, efficient screening strategy to identify protein binders. Despite recent advancements in this field, most DEL syntheses are limited by the presence of sensitive DNA-based constructs. Here, we describe the design, synthesis, and validation experiments performed for a 3.7 million-member DEL, generated using diverse skeleton architectures with varying exit vectors, derived from DOS, to achieve structural diversity beyond what is possible by varying appendages alone. We will make this DEL available to the academic scientific community to increase access to novel structural features and accelerate early-phase drug discovery.

biochemistry↗