Biology subjects

Nomura, D. K.

Publications and source records attributed to Nomura, D. K..

At least 19 recordsLinked to original sources

bioRxiv2026

Stereoselective Covalent Inhibitor of the Ovarian Cancer-Driving Transcription Factor PAX8

Transcription factors remain among the most challenging therapeutic targets in part because they lack well-defined ligandable binding pockets. We recently showed that aberrantly reactive cysteines in transcription factors can be directly targeted with electrophilic small molecules to induce selective transcription factor destabilization and degradation. Here, we extend this strategy to the lineage-defining oncogenic transcription factor PAX8, a critical driver of ovarian cancer. Screening of a chemically diverse library of more than 3,000 cysteine-reactive compounds against an endogenously HiBiT-tagged PAX8 reporter identified a sulfinyl aziridine chemotype that selectively reduced PAX8 abundance. Structure-activity and stereochemical analyses revealed highly enantio- and diastereoselective activity, identifying KL6-159A as the lead compound. Quantitative proteomics demonstrated selective loss of PAX8, while cellular thermal shift analysis and chemoproteomic profiling established direct covalent engagement of PAX8 at cysteine C57. Mutation of C57 completely abolished KL6-159A-induced PAX8 depletion, demonstrating that this residue is essential for compound activity. Transcriptomic profiling revealed broad suppression of the PAX8 transcriptional program, with FOXM1 emerging as the most significantly downregulated regulatory network together with numerous established PAX8 target genes. Collectively, these studies establish direct covalent engagement, transcriptional inhibition, and destabilization of PAX8 and further demonstrate the generality of covalent chemoproteomic approaches for drugging previously intractable transcription factors.

biochemistry↗

bioRxiv2026

An Optimized RNF126-Targeting Covalent Handle for Molecular Glue Degraders

Molecular glue degraders represent a powerful modality for targeting proteins that are refractory to traditional inhibition. However, rational design principles for molecular glue degraders remain poorly defined. Previously, we reported a chemistry-centric strategy to identify covalent degradative handles that, when appended to established ligands, convert non-degradative inhibitors into molecular glue degraders by engaging permissive E3 ligases. This effort identified a fumarate-based electrophilic handle that covalently modified the E3 ligase RNF126, enabling degradation of multiple protein targets when transplanted across diverse ligands. Despite its conceptual impact, the high intrinsic reactivity and cytotoxicity of the fumarate handle limited its translational utility. Here, we report the development of an optimized and metabolically stabilized RNF126-targeting covalent handle incorporating a trans-cyclobutane linker that exhibits reduced glutathione reactivity and diminished cytotoxicity while retaining robust degradative activity. When appended to the BET bromodomain inhibitor JQ1, this optimized handle yielded a potent and selective BRD4 degrader whose activity was dependent on RNF126. Importantly, transplantation of this handle onto a previously non-inhibitory ligand targeting the androgen receptor (AR) and its truncation variant, AR-V7, enabled selective degradation of both AR and AR-V7 in androgen-independent prostate cancer cells, thereby robustly inhibiting AR transcriptional activity beyond the established AR antagonist enzalutamide. Collectively, these findings demonstrate an optimized RNF126-based covalent handle for the rational development of molecular glue degraders against transcriptional regulators, including undruggable variants such as AR-V7.

biochemistry↗

bioRxiv2025

Discovery of Non-Degradative Covalent Molecular Glues for Transcriptional Reprogramming

Transcriptional reprogramming through induced proximity has emerged as a powerful strategy for modulating the expression of oncogenic and tumor-suppressive genes. Inspired by transcriptional reprogramming approaches such as transcriptional/epigenetic chemical inducers of proximity (TCIPs) that link BCL6 inhibitors to transcriptional regulators, we sought to develop covalent ligands that rewire BCL6 proximity to selectively suppress MYC transcriptional output while derepressing BCL6 target loci. Through a chemistry-driven and chemoproteomics-enabled design strategy, we generated a panel of BCL6-based electrophile-bearing hybrid ligands and identified a nondegradative molecular glue, ZD-1-186, that potently suppresses MYC and robustly induces CDKN1A (p21) in diffuse large B-cell lymphoma cells. ZD-1-186 downregulates MYC more effectively than BCL6 inhibitors or degraders, while strongly derepressing canonical BCL6 targets, including p21. Through BCL6 pulldown proteomics, ZD-1-186 induced a selective recruitment of the noncanonical BAF complex subunit BRD9 to BCL6 and covalently modified BRD9 at C288. Pharmacologic inhibition or genetic knockdown of BRD9 attenuated ZD-1-186-mediated MYC suppression and blunted p21 induction. Transcriptomic profiling of ZD-1-186 showed simultaneous derepression of BCL6-repressive loci and suppression of MYC transcriptional programs. These findings demonstrated that ZD-1-186 acted as a transcriptional rewiring glue, recruiting BRD9 to BCL6-repressive loci to activate tumor-suppressive transcription, while also potentially redirecting BCL6 to BRD9-bound oncogenic loci. Overall, our work provides a blueprint for the rational discovery and design of electrophile-enabled, nondegradative molecular glues for targeted transcriptional rewiring.

biochemistry↗

bioRxiv2025

Induced ubiquitination bypasses canonical ERAD to drive ER protein degradation

Heterobifunctional proteolysis-targeting chimeras (PROTACs) have emerged as a powerful strategy to degrade disease-relevant proteins, enabling targeting of previously "undruggable" proteins. Current degrader molecules primarily target cytosolic substrates, yet nearly one-third of the proteome resides in or transits the endoplasmic reticulum (ER), including receptors, secreted factors, and biosynthetic enzymes with high therapeutic relevance. Whether ER-localized proteins can be broadly targeted for induced degradation remains an open question. To address this gap, we employed a panel of fluorescent reporter cell lines and used the dTAG chemical-genetic system to recruit cytosolic E3 ligases. While lumenal substrates segregated from the cytosol were resistant to degradation, recruitment of cytosolic ligases effectively degraded ER membrane proteins across multiple topologies and with post-translational modifications. CRISPR genetic screens revealed that the induced degradation required the expected cullin RING ligase complexes but surprisingly bypassed ER-associated degradation (ERAD) machinery, with the exception of the AAA ATPase VCP. Mechanistic studies demonstrated that substrate ubiquitination was essential for VCP binding, and cleavage of ubiquitin chains released VCP, suggesting a model in which VCP directly extracts substrates independent of a dislocation apparatus. Extending this strategy to an endogenous substrate, we synthesized an HMGCR ERAD-TAC by linking atorvastatin to a cereblon E3 ligase recruiter and found that HMGCR degradation was likewise VCP-dependent. Together, these findings demonstrate that ER membrane proteins are generally susceptible to induced degradation via cytosolic ligase recruitment, uncovering a VCP-centered mechanism that operates independently of membrane-embedded ERAD machinery. This work establishes foundational principles for extending targeted protein degradation to the early secretory pathway. SIGNIFICANCE STATEMENTTargeted protein degradation has transformed drug discovery. Nearly one-third of the proteome reside in or transit the endoplasmic reticulum (ER), a compartment rich in therapeutically relevant but structurally complex targets. Whether these ER proteins can be broadly degraded using PROTACs has remained unknown. Here, we define the minimal requirements for degrading ER membrane proteins by recruiting cytosolic E3 ligases. Using chemical-genetic tools, genetic screens, and a statin-based degrader, we show that ubiquitination engages the VCP extraction machinery, enabling degradation of diverse ER membrane proteins independent of canonical ER-associated degradation components. These findings reveal a ubiquitin-driven route for membrane protein turnover, expand the landscape of druggable ER proteins, and establish principles for designing degraders operating in the early secretory pathway.

cell biology↗

bioRxiv2025

Targeted Transcriptional Repression by Induced Proximity

Most cancer-driving proteins remain "undruggable" due to the absence of ligandable pockets and their reliance on intrinsically disordered or protein-DNA/protein-protein interactions. Transcription factors, which orchestrate oncogenic gene expression programs, are particularly challenging: they turn over rapidly, evade durable pharmacological inhibition, and resist even emerging targeted protein degradation strategies. Here, we describe a new induced-proximity therapeutic modality, Transcriptional Regulation via Active Control of Epigenetic Reprogramming (TRACER), that enforces locus-specific transcriptional silencing by recruiting endogenous corepressor complexes to transcription factor binding sites. We developed small-molecule TRACERs that tether methyl-CpG binding domain protein 2 (MBD2) and the Nucleosome Remodeling and Deacetylase (NuRD) complex to transcription factor-directed ligands. An estrogen receptor (ER) TRACER potently suppressed ER transcriptional activity in breast cancer cells, downregulated canonical ER target genes, and required MBD2 and histone deacetylase (HDAC1/2) for activity, confirming on-target epigenetic repression. Extending this approach to prostate cancer, an androgen receptor (AR) TRACER transcriptionally repressed both full-length AR and the drug-resistant truncation variant AR-V7, achieving >90% inhibition of AR transcriptional activity in androgen-independent prostate cancer cells with locus-specific gene repression. We further show that TRACERs can be modularly reprogrammed to recruit alternative repressors, including PRC2. Collectively, these findings establish TRACERs as a generalizable modality to pharmacologically silence undruggable transcription factors through targeted epigenetic reprogramming, offering a powerful new strategy for treating cancers refractory to existing therapies.

biochemistry↗

bioRxiv2025

Covalent Degraders of Immune Regulatory Transcription Factors IRF8 and IRF5

Transcription factors are among the most challenging targets for drug discovery due to their lack of classical binding pockets and high degree of intrinsic disorder, despite the therapeutic importance of many of these proteins. IRF5 and IRF8 are key transcriptional regulators of innate immune signaling that orchestrate pro-inflammatory gene expression programs in response to stimuli such as toll-like receptor activation, making them central players in autoimmune and inflammatory diseases. Despite their therapeutic interest, direct targeting of IRF5 and IRF8 has remained challenging. Through a screen originally intended to identify cysteine-reactive electrophilic ligands that could directly and covalently engage and degrade IRF5, we identified an acrylamide hit, EN1033, that not only targeted and degraded IRF5 but also degraded a related inflammatory transcription factor, IRF8, more robustly and rapidly. EN1033 destabilized and degraded IRF5 and IRF8 by covalently targeting C28 and C223, respectively, as evidenced by the attenuation of their degradation through mutagenesis of these cysteines. We also found that IRF8 loss led to downregulation and inhibition of IRF5 activity, suggesting crosstalk between these two transcription factors, both of which are targeted by EN1033. Upon exploring structure-activity relationships, we identified an optimized compound, TH-B10, that more potently and selectively targeted and degraded IRF8 and, secondarily, downregulated IRF5 by targeting C223 on IRF8. Overall, we identify an early-stage pathfinder molecule, TH-B10, that directly covalently targets and degrades IRF8 and secondarily modulates IRF5 to shut down pro-inflammatory transcriptional activity.

biochemistry↗

bioRxiv2025

DCAF16-Based Covalent Degradative Handles for the Modular Design of Degraders

Targeted protein degradation (TPD) is a powerful strategy for targeting and eliminating disease-causing proteins. While heterobifunctional Proteolysis-Targeting Chimeras (PROTACs) are more modular, the rational design of monovalent or molecular glue degraders remains challenging. In this study, we generated a small library of BET-domain inhibitor JQ1 analogs bearing elaborated electrophilic handles to identify permissive covalent degradative handles and E3 ligase pairs. We identified an elaborated fumaramide handle that, when appended onto JQ1, led to the proteasome-dependent degradation of BRD4. Further characterization revealed that the E3 ubiquitin ligase CUL4DCAF16--a common E3 ligase target of electrophilic degraders--was responsible for BRD4 loss by covalently targeting C173 on DCAF16. While this original fumaramide handle, when appended onto other protein-targeting ligands, did not accommodate the degradation of other neo-substrates, a truncated version of this handle attached to JQ1 was still capable of degrading BRD4, now through targeting both C173 and C178. This truncated fumaramide handle, when appended on various protein targeting ligands, and was also more permissive in degrading other neo-substrates, including CDK4/6, SMARCA2/4, and the androgen receptor (AR). We further demonstrated that this optimized truncated fumaramide handle, when transplanted onto an AR DNA binding domain-targeting ligand, could degrade both AR and the undruggable truncation variant of AR, AR-V7, in androgen-independent prostate cancer cells in a DCAF16-dependent manner. Overall, we have identified a unique DCAF16-targeting covalent degradative handle that can be transplanted across several protein-targeting ligands to induce the degradation of their respective targets for the modular design of monovalent or bifunctional degraders.

biochemistry↗

bioRxiv2025

Sulfinyl Aziridines as Stereoselective Covalent Destabilizing Degraders of the Oncogenic Transcription Factor MYC

While MYC is a significant oncogenic transcription factor driver of cancer, directly targeting MYC has remained challenging due to its intrinsic disorder and poorly defined structure, deeming it "undruggable." Whether transient pockets formed within intrinsically disordered and unstructured regions of proteins can be selectively targeted with small molecules remains an outstanding challenge. Here, we developed a bespoke stereochemically-paired spirocyclic oxindole aziridine covalent library and screened this library for degradation of MYC. Through this screen, we identified a hit covalent ligand KL2-236, bearing a unique sulfinyl aziridine warhead, that engaged MYC in vitro as pure MYC/MAX protein complex and in situ in cancer cells to destabilize MYC, inhibit MYC transcriptional activity and degrade MYC in a proteasome-dependent manner through targeting intrinsically disordered C203 and D205 residues. Notably, this reactivity was most pronounced for specific stereoisomers of KL2-236 with a diastereomer KL4-019 that was largely inactive. Mutagenesis of both C203 and D205 completely attenuated KL2-236-mediated MYC degradation. We have also optimized our initial KL2-236 hit compound to generate a more durable MYC degrader KL4-219A in cancer cells. Our results reveal a novel ligandable site within MYC and indicate that certain intrinsically disordered regions within high-value protein targets, such as MYC, can be interrogated by isomerically unique chiral small molecules, leading to destabilization and degradation.

cancer biology↗

bioRxiv2025

Covalent Destabilizing Degrader of AR and AR-V7 in Androgen-Independent Prostate Cancer Cells

Androgen-independent prostate cancers, correlated with heightened aggressiveness and poor prognosis, are caused by mutations or deletions in the androgen receptor (AR) or expression of truncated variants of AR that are constitutively activated. Currently, drugs and drug candidates against AR target the steroid-binding domain to antagonize or degrade AR. However, these compounds cannot therapeutically access largely intrinsically disordered truncated splice variants of AR, such as AR-V7, that only possess the DNA binding domain and are missing the ligand binding domain. Targeting intrinsically disordered regions within transcription factors has remained challenging and is considered "undruggable". Herein, we leveraged a cysteine-reactive covalent ligand library in a cellular screen to identify degraders of AR and AR-V7 in androgen-independent prostate cancer cells. We identified a covalent compound EN1441 that selectively degrades AR and AR-V7 in a proteasome-dependent manner through direct covalent targeting of an intrinsically disordered cysteine C125 in AR and AR-V7. EN1441 causes significant and selective destabilization of AR and AR-V7, leading to aggregation of AR/AR-V7 and subsequent proteasome-mediated degradation. Consistent with targeting both AR and AR-V7, we find that EN1441 completely inhibits total AR transcriptional activity in androgen-independent prostate cancer cells expressing both AR and AR-V7 compared to AR antagonists or degraders that only target the ligand binding domain of full-length AR, such as enzalutamide and ARV-110. Our results put forth a pathfinder molecule EN1441 that targets an intrinsically disordered cysteine within AR to destabilize, degrade, and inhibit both AR and AR-V7 in androgen-independent prostate cancer cells and highlights the utility of covalent ligand discovery approaches in directly targeting, destabilizing, inhibiting, and degrading classically undruggable transcription factor targets.

cancer biology↗

bioRxiv2024

DCAF16-Based Covalent Handle for the Rational Design of Monovalent Degraders

Targeted protein degradation with monovalent molecular glue degraders is a powerful therapeutic modality for eliminating disease causing proteins. However, rational design of molecular glue degraders remains challenging. In this study, we sought to identify a transplantable and linker-less covalent handle that could be appended onto the exit vector of various protein-targeting ligands to induce the degradation of their respective targets. Using the BET family inhibitor JQ1 as a testbed, we synthesized and screened a series of covalent JQ1 analogs and identified a vinylsulfonyl piperazine handle that led to the potent and selective degradation of BRD4 in cells. Through chemoproteomic profiling, we identified DCAF16 as the E3 ligase responsible for BRD4 degradation--an E3 ligase substrate receptor that has been previously covalently targeted for molecular glue-based degradation of BRD4. Interestingly, we demonstrated that this covalent handle can be transplanted across a diverse array of protein-targeting ligands spanning many different protein classes to induce the degradation of CDK4, the androgen receptor, BTK, SMARCA2/4, and BCR-ABL/c-ABL. Our study reveals a DCAF16-based covalent degradative and linker-less chemical handle that can be attached to protein-targeting ligands to induce the degradation of several different classes of protein targets.

biochemistry↗

bioRxiv2023

Covalent 14-3-3 Molecular Glues and Heterobifunctional Molecules Against Nuclear Transcription Factors and Regulators

14-3-3 proteins have the unique ability to bind and sequester a multitude of diverse phosphorylated signaling proteins and transcription factors. Many previous studies have shown that 14-3-3 interactions with specific phosphorylated substrate proteins can be enhanced through small-molecule natural product or fully synthetic molecular glue interactions. However, enhancing 14-3-3 interactions with both therapeutically intractable transcription factor substrates as well as potential neo-substrates to sequester and inhibit their function has remained elusive. One of the 14-3-3 proteins, 14-3-3{sigma} or SFN, has a cysteine C38 at the substrate binding interface near sites where previous 14-3-3 molecular glues have been found to bind. In this study, we screened a fully synthetic cysteine-reactive covalent ligand library to identify molecular glues that enhance interaction of 14-3-3{sigma} with not only druggable transcription factors such as estrogen receptor (ER), but also challenging oncogenic transcription factors such as YAP and TAZ that are part of the Hippo transducer pathway. We identified a hit EN171 that covalently targets 14-3-3 to enhance 14-3-3 interactions with ER, YAP, and TAZ leading to impaired estrogen receptor and Hippo pathway transcriptional activity. We further demonstrate that EN171 could not only be used as a molecular glue to enhance native protein interactions, but also could be used as a covalent 14-3-3 recruiter in heterobifunctional molecules to sequester nuclear neo-substrates such as BRD4 into the cytosol. Overall, our study reveals a covalent ligand that acts as a novel 14-3-3 molecular glue for challenging transcription factors such as YAP and TAZ and also demonstrates that these glues can be potentially utilized in heterobifunctional molecules to sequester nuclear neo-substrates out of the nucleus and into the cytosol to enable targeted protein localization.

biochemistry↗

bioRxiv2023

Covalent Degrader of the Oncogenic Transcription Factor β-Catenin

{beta}-catenin (CTNNB1) is an oncogenic transcription factor that is important in cell-cell adhesion and transcription of cell proliferation and survival genes that drives the pathogenesis of many different types of cancers. However, direct pharmacological targeting of CTNNB1 has remained challenging deeming this transcription factor as "undruggable." Here, we have performed a screen with a library of cysteine-reactive covalent ligands to identify a monovalent degrader EN83 that depletes CTNNB1 in a ubiquitin-proteasome-dependent manner. We show that EN83 directly and covalently targets CTNNB1 through targeting four distinct cysteines within the armadillo repeat domain--C439, C466, C520, and C619--leading to a destabilization of CTNNB1. Using covalent chemoproteomic approaches, we show that EN83 directly engages CTNNB1 in cells with a moderate degree of selectivity. We further demonstrate that direct covalent targeting of three of these four cysteines--C466, C520, and C619--in cells contributes to CTNNB1 degradation in cells. We also demonstrate that EN83 can be further optimized to yield more potent CTNNB1 binders and degraders. Our results show that chemoproteomic approaches can be used to covalently target and degrade challenging transcription factors like CTNNB1 through a destabilization-mediated degradation.

biochemistry↗

bioRxiv2023

Targeted Protein Degradation through Recruitment of the CUL4A Complex Adaptor Protein DDB1

Targeted protein degradation has arisen as a powerful therapeutic modality for eliminating proteins. Thus far, most heterobifunctional Proteolysis Targeting Chimeras (PROTACs) have utilized recruiters against substrate receptors of Cullin RING E3 ubiquitin ligases, such as cereblon and VHL. However, previous studies have surprisingly uncovered molecular glue degraders that exploit a CUL4A adaptor protein DDB1 to degrade neosubstrate proteins. Here, we sought to investigate whether DDB1 recruiters can be discovered that can be exploited for PROTAC applications. We utilized activity-based protein profiling and cysteine chemoproteomic screening to identify a covalent recruiter that targets C173 on DDB1 and exploited this recruiter to develop PROTACs against BRD4 and androgen receptor (AR). We demonstrated that the BRD4 PROTAC results in selective degradation of the short BRD4 isoform over the long isoform in a proteasome, NEDDylation, and DDB1-dependent manner. We also demonstrated degradation of AR with the AR PROTAC in prostate cancer cells. Our study demonstrated that covalent chemoproteomic approaches can be used to discover recruiters against Cullin RING adapter proteins and that these recruiters can be used for PROTAC applications to degrade neo-substrates.

biochemistry↗

bioRxiv2023

Covalent Targeting of Glutamate Cysteine Ligase to Inhibit Glutathione Synthesis

Dysregulated oxidative stress plays a major role in cancer pathogenesis and some types of cancer cells are particularly vulnerable to inhibiting cellular antioxidant capacity. Glutamate-cysteine ligase (GCL) is the first and rate-limiting step in the synthesis of the major cellular antioxidant glutathione (GSH). Developing a GCL inhibitor may be an attractive therapeutic strategy for certain cancer types that are particularly sensitive to oxidative stress. In this study, we reveal a cysteine-reactive covalent ligand EN25 that covalently targets an allosteric cysteine C114 on GCLM, the modifier subunit of GCL, leading to inhibition of GCL activity, lowering of cellular GSH levels, and impaired cell viability in ARID1A-deficient cancer cells that are particularly vulnerable to glutathione depletion, but not in ARID1A-positive cancer cells. Our studies uncover a novel potential ligandable site within GCLM that can be targeted to inhibit the GSH synthesis in cancer cells to target vulnerable cancer cell types.

biochemistry↗

bioRxiv2023

Ophiobolin A Covalently Targets Complex IV Leading to Mitochondrial Metabolic Collapse in Cancer Cells

SummaryOphiobolin A (OPA) is a sesterterpenoid fungal natural product with broad anti-cancer activity. While OPA possesses multiple electrophilic moieties that can covalently react with nucleophilic amino acids on proteins, the proteome-wide targets and mechanism of OPA remain poorly understood in many contexts. In this study, we used covalent chemoproteomic platforms to map the proteome-wide reactivity of OPA in a highly sensitive lung cancer cell line. Among several proteins that OPA engaged, we focused on two targets--cysteine C53 of HIG2DA and lysine K72 of COX5A--that are part of complex IV of the electron transport chain and contributed significantly to the anti-proliferative activity. OPA activated mitochondrial respiration in a HIG2DA and COX5A-dependent manner, led to an initial spike in mitochondrial ATP, but then compromised mitochondrial membrane potential leading to ATP depletion. We have used chemoproteomic strategies to discover a unique anti-cancer mechanism of OPA through activation of complex IV leading to compromised mitochondrial energetics and rapid cell death.

biochemistry↗

bioRxiv2023

Chemoproteomic Profiling Reveals that Anti-Cancer Natural Product Dankastatin B Covalently Targets Mitochondrial VDAC3

Chlorinated gymnastatin and dankastatin alkaloids derived from the fungal strain Gymnascella dankaliensis have been reported to possess significant anti-cancer activity but their mode of action is unknown. These members possess electrophilic functional groups that may undergo covalent bond formation with specific proteins to exert their biological activity. To better understand the mechanism of action of this class of natural products, we mapped the proteome-wide cysteine-reactivity of the most potent of these alkaloids, dankastatin B, using activitybased protein profiling chemoproteomic approaches. We identified a primary target of dankastatin B in breast cancer cells as cysteine C65 of the voltage-dependent anion selective channel on the outer mitochondrial membrane VDAC3. We demonstrated direct and covalent interaction of dankastatin B with VDAC3. VDAC3 knockdown conferred hyper-sensitivity to dankastatin B-mediated anti-proliferative effects in breast cancer cells indicating that VDAC3 was at least partially involved in the anti-cancer effects of this natural product. Our study reveals a potential mode of action of dankastatin B through covalent targeting of VDAC3 and highlight the utility of chemoproteomic approaches in gaining mechanistic understanding of electrophilic natural products.

biochemistry↗

bioRxiv2023

A Cellular Platform for Production of C4 Monomers

Living organisms carry out a wide range of remarkable functions, including the synthesis of thousands of simple and complex chemical structures for cellular growth and maintenance. The manipulation of this reaction network has allowed for the genetic engineering of cells for targeted chemical synthesis, but it remains challenging to alter the program underlying their fundamental chemical behavior. By taking advantage of the unique ability of living systems to use evolution to find solutions to complex problems, we have achieved ~95% theoretical yield of three C4 commodity chemicals, n-butanol, 1,3-butanediol, and 4-hydroxy-2-butanone. Genomic sequencing of the evolved strains identified pcnB and rpoBC as two gene loci that are able to alter carbon flow by remodeling the transcriptional landscape of the cell, highlighting the potential of synthetic pathways as a tool to identify metabolic control points.

synthetic biology↗

bioRxiv2022

Targeted Protein Degradation through E2 Recruitment

Targeted protein degradation (TPD) with Proteolysis Targeting Chimeras (PROTACs), heterobifunctional compounds consisting of protein targeting ligands linked to recruiters of E3 ubiquitin ligases, has arisen as a powerful therapeutic modality to induce the proximity of target proteins with E3 ligases to ubiquitinate and degrade specific proteins in cells. Thus far, PROTACs have primarily exploited the recruitment of E3 ubiquitin ligases or their substrate adapter proteins but have not exploited the recruitment of more core components of the ubiquitin-proteasome system (UPS). In this study, we used covalent chemoproteomic approaches to discover a covalent recruiter against the E2 ubiquitin conjugating enzyme UBE2D--EN67--that targets an allosteric cysteine, C111, without affecting the enzymatic activity of the protein. We demonstrated that this UBE2D recruiter could be used in heterobifunctional degraders to degrade neo-substrate targets in a UBE2D-dependent manner, including BRD4 and the androgen receptor. Overall, our data highlight the potential for the recruitment of core components of the UPS machinery, such as E2 ubiquitin conjugating enzymes, for TPD, and underscore the utility of covalent chemoproteomic strategies for identifying novel recruiters for additional components of the UPS.

biochemistry↗