Budayeva, H. G. | bioRxiv Science

bioRxiv2025

Rational design of potent small molecule SMARCA2/A4 (BRM/BRG1) degraders acting via the recruitment of FBXO22

Target-anchored monovalent degraders are more drug-like than their bivalent counterparts, Proteolysis Targeting Chimeras (PROTACs), while offering greater target specificity control than the E3 ligase-anchored monovalent degraders, also known as molecular glues. However, their discovery has typically been serendipitous, and the rules governing their identification remain unclear. This study focused on the intentional discovery of SMARCA2/A4 monovalent degraders using a library based on SMARCA2/A4 bromodomain-binding ligands. Compound G-6599 emerged as a lead candidate, showing exceptional degradation potency and specificity for SMARCA2/A4. Mechanistic studies revealed that G-6599 operates through the ubiquitin-proteasome pathway and the E3 ligase FBXO22. G-6599 was shown to promote ternary complex formation between SMARCA2 and FBXO22 involving covalent conjugation to a cysteine residue on the latter. Unlike other recently identified FBXO22-dependent degraders, it does not require biotransformation. The selective degradation ability of G-6599, along with its unique mechanism, highlights the therapeutic potential of target-anchored monovalent degraders.

cancer biology↗

bioRxiv2023

Increasing the Throughput and Reproducibility of Activity-Based Proteome Profiling Studies with Hyperplexing and Intelligent Data Acquisition

Intelligent data acquisition (IDA) strategies, such as real-time database search (RTS), have improved the depth of proteome coverage for experiments that utilize isobaric labels and gas phase purification techniques (i.e., SPS-MS3). While most applications of IDA have been focused on the analysis of protein abundance, these approaches have recently been applied to activity-based proteome profiling (ABPP) studies aimed at characterization of protein site engagement by small molecules. In this work, we extend IDA capabilities offered by vendor software through a program called InSeqAPI. First, we demonstrate robust performance of InSeqAPI in the analysis of biotinylated cysteine peptides from ABPP experiments. Then, we describe PairQuant, a method within InSeqAPI designed for the hyperplexing approach that utilizes protein-level isotopic labeling and peptide-level TMT labeling. PairQuant allows for TMT analysis of 36 conditions in a single sample and achieves [~]98% coverage of both peptide pair partners in a hyperplexed experiment as well as a 40% improvement in the number of quantified cysteine sites compared to non-RTS acquisition. We applied this method in ABPP study of ligandable cysteine sites in the nucleus leading to an identification of additional druggable sites on protein-and DNA-interaction domains of transcription regulators and on nuclear ubiquitin ligases.

biochemistry↗