RESUMEN
Electrophilic compounds originating from nature or chemical synthesis have profound effects on immune cells. These compounds are thought to act by cysteine modification to alter the functions of immune-relevant proteins; however, our understanding of electrophile-sensitive cysteines in the human immune proteome remains limited. Here, we present a global map of cysteines in primary human T cells that are susceptible to covalent modification by electrophilic small molecules. More than 3,000 covalently liganded cysteines were found on functionally and structurally diverse proteins, including many that play fundamental roles in immunology. We further show that electrophilic compounds can impair T cell activation by distinct mechanisms involving the direct functional perturbation and/or degradation of proteins. Our findings reveal a rich content of ligandable cysteines in human T cells and point to electrophilic small molecules as a fertile source for chemical probes and ultimately therapeutics that modulate immunological processes and their associated disorders.
Asunto(s)
Cisteína/metabolismo , Ligandos , Linfocitos T/metabolismo , Acetamidas/química , Acetamidas/farmacología , Acrilamidas/química , Acrilamidas/farmacología , Células Cultivadas , Humanos , Proteínas Inhibidoras de la Apoptosis/metabolismo , Activación de Linfocitos/efectos de los fármacos , Proteínas Tirosina Quinasas/metabolismo , Proteolisis/efectos de los fármacos , Proteoma/química , Proteoma/metabolismo , Estereoisomerismo , Linfocitos T/citología , Linfocitos T/inmunología , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Most human proteins lack chemical probes, and several large-scale and generalizable small-molecule binding assays have been introduced to address this problem. How compounds discovered in such "binding-first" assays affect protein function, nonetheless, often remains unclear. Here, we describe a "function-first" proteomic strategy that uses size exclusion chromatography (SEC) to assess the global impact of electrophilic compounds on protein complexes in human cells. Integrating the SEC data with cysteine-directed activity-based protein profiling identifies changes in protein-protein interactions that are caused by site-specific liganding events, including the stereoselective engagement of cysteines in PSME1 and SF3B1 that disrupt the PA28 proteasome regulatory complex and stabilize a dynamic state of the spliceosome, respectively. Our findings thus show how multidimensional proteomic analysis of focused libraries of electrophilic compounds can expedite the discovery of chemical probes with site-specific functional effects on protein complexes in human cells.
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Proteómica , Factores de Transcripción , Humanos , Proteómica/métodos , Cisteína/metabolismo , LigandosRESUMEN
WRN helicase is a promising target for treatment of cancers with microsatellite instability (MSI) due to its essential role in resolving deleterious non-canonical DNA structures that accumulate in cells with faulty mismatch repair mechanisms1-5. Currently there are no approved drugs directly targeting human DNA or RNA helicases, in part owing to the challenging nature of developing potent and selective compounds to this class of proteins. Here we describe the chemoproteomics-enabled discovery of a clinical-stage, covalent allosteric inhibitor of WRN, VVD-133214. This compound selectively engages a cysteine (C727) located in a region of the helicase domain subject to interdomain movement during DNA unwinding. VVD-133214 binds WRN protein cooperatively with nucleotide and stabilizes compact conformations lacking the dynamic flexibility necessary for proper helicase function, resulting in widespread double-stranded DNA breaks, nuclear swelling and cell death in MSI-high (MSI-H), but not in microsatellite-stable, cells. The compound was well tolerated in mice and led to robust tumour regression in multiple MSI-H colorectal cancer cell lines and patient-derived xenograft models. Our work shows an allosteric approach for inhibition of WRN function that circumvents competition from an endogenous ATP cofactor in cancer cells, and designates VVD-133214 as a promising drug candidate for patients with MSI-H cancers.
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Regulación Alostérica , Descubrimiento de Drogas , Inhibidores Enzimáticos , Proteómica , Helicasa del Síndrome de Werner , Animales , Femenino , Humanos , Masculino , Ratones , Regulación Alostérica/efectos de los fármacos , Línea Celular Tumoral , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/enzimología , Neoplasias Colorrectales/patología , Cisteína/efectos de los fármacos , Cisteína/metabolismo , Roturas del ADN de Doble Cadena/efectos de los fármacos , Descubrimiento de Drogas/métodos , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/química , Inestabilidad de Microsatélites , Modelos Moleculares , Helicasa del Síndrome de Werner/antagonistas & inhibidores , Helicasa del Síndrome de Werner/química , Helicasa del Síndrome de Werner/metabolismo , Ensayos Antitumor por Modelo de Xenoinjerto , Muerte Celular/efectos de los fármacos , Adenosina Trifosfato/metabolismoRESUMEN
To study how microbes establish themselves in a mammalian gut environment, we colonized germ-free mice with microbial communities from human, zebrafish, and termite guts, human skin and tongue, soil, and estuarine microbial mats. Bacteria from these foreign environments colonized and persisted in the mouse gut; their capacity to metabolize dietary and host carbohydrates and bile acids correlated with colonization success. Cohousing mice harboring these xenomicrobiota or a mouse cecal microbiota, along with germ-free "bystanders," revealed the success of particular bacterial taxa in invading guts with established communities and empty gut habitats. Unanticipated patterns of ecological succession were observed; for example, a soil-derived bacterium dominated even in the presence of bacteria from other gut communities (zebrafish and termite), and human-derived bacteria colonized germ-free bystander mice before mouse-derived organisms. This approach can be generalized to address a variety of mechanistic questions about succession, including succession in the context of microbiota-directed therapeutics.
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Bacterias/clasificación , Bacterias/crecimiento & desarrollo , Tracto Gastrointestinal/microbiología , Ratones/microbiología , Animales , Bacterias/metabolismo , Ecosistema , Estuarios , Vida Libre de Gérmenes , Humanos , Isópteros/microbiología , Interacciones Microbianas , Piel/microbiología , Microbiología del Suelo , Simbiosis , Lengua/microbiología , Pez Cebra/microbiologíaRESUMEN
Caspase proteases are principal mediators of apoptosis, where they cleave hundreds of proteins. Phosphorylation also plays an important role in apoptosis, although the extent to which proteolytic and phosphorylation pathways crosstalk during programmed cell death remains poorly understood. Using a quantitative proteomic platform that integrates phosphorylation sites into the topographical maps of proteins, we identify a cohort of over 500 apoptosis-specific phosphorylation events and show that they are enriched on cleaved proteins and clustered around sites of caspase proteolysis. We find that caspase cleavage can expose new sites for phosphorylation, and, conversely, that phosphorylation at the +3 position of cleavage sites can directly promote substrate proteolysis by caspase-8. This study provides a global portrait of the apoptotic phosphoproteome, revealing heretofore unrecognized forms of functional crosstalk between phosphorylation and caspase proteolytic pathways that lead to enhanced rates of protein cleavage and the unveiling of new sites for phosphorylation.
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Apoptosis , Proteoma/análisis , Proteoma/metabolismo , Caspasas/metabolismo , Humanos , Modelos Moleculares , Fosforilación , Proteolisis , Transducción de SeñalRESUMEN
Covalent chemistry represents an attractive strategy for expanding the ligandability of the proteome, and chemical proteomics has revealed numerous electrophile-reactive cysteines on diverse human proteins. Determining which of these covalent binding events affect protein function, however, remains challenging. Here we describe a base-editing strategy to infer the functionality of cysteines by quantifying the impact of their missense mutation on cancer cell proliferation. The resulting atlas, which covers more than 13,800 cysteines on more than 1,750 cancer dependency proteins, confirms the essentiality of cysteines targeted by covalent drugs and, when integrated with chemical proteomic data, identifies essential, ligandable cysteines in more than 160 cancer dependency proteins. We further show that a stereoselective and site-specific ligand targeting an essential cysteine in TOE1 inhibits the nuclease activity of this protein through an apparent allosteric mechanism. Our findings thus describe a versatile method and valuable resource to prioritize the pursuit of small-molecule probes with high function-perturbing potential.
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Cisteína , Neoplasias , Humanos , Cisteína/química , Proteómica , Edición Génica , Proteoma/química , Neoplasias/genética , Proteínas NuclearesRESUMEN
Covalent chemistry coupled with activity-based protein profiling (ABPP) offers a versatile way to discover ligands for proteins in native biological systems. Here, we describe a set of stereo- and regiochemically defined spirocycle acrylamides and the analysis of these electrophilic "stereoprobes" in human cancer cells by cysteine-directed ABPP. Despite showing attenuated reactivity compared to structurally related azetidine acrylamide stereoprobes, the spirocycle acrylamides preferentially liganded specific cysteines on diverse protein classes. One compound termed ZL-12A promoted the degradation of the TFIIH helicase ERCC3. Interestingly, ZL-12A reacts with the same cysteine (C342) in ERCC3 as the natural product triptolide, which did not lead to ERCC3 degradation but instead causes collateral loss of RNA polymerases. ZL-12A and triptolide cross-antagonized one another's protein degradation profiles. Finally, we provide evidence that the antihypertension drug spironolactoneâpreviously found to promote ERCC3 degradation through an enigmatic mechanismâalso reacts with ERCC3_C342. Our findings thus describe monofunctional degraders of ERCC3 and highlight how covalent ligands targeting the same cysteine can produce strikingly different functional outcomes.
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Acrilamida , Diterpenos , Fenantrenos , Humanos , Cisteína/química , Proteómica , Compuestos EpoxiRESUMEN
The Janus tyrosine kinase (JAK) family of non-receptor tyrosine kinases includes four isoforms (JAK1, JAK2, JAK3, and TYK2) and is responsible for signal transduction downstream of diverse cytokine receptors. JAK inhibitors have emerged as important therapies for immun(onc)ological disorders, but their use is limited by undesirable side effects presumed to arise from poor isoform selectivity, a common challenge for inhibitors targeting the ATP-binding pocket of kinases. Here we describe the chemical proteomic discovery of a druggable allosteric cysteine present in the non-catalytic pseudokinase domain of JAK1 (C817) and TYK2 (C838), but absent from JAK2 or JAK3. Electrophilic compounds selectively engaging this site block JAK1-dependent trans-phosphorylation and cytokine signaling, while appearing to act largely as 'silent' ligands for TYK2. Importantly, the allosteric JAK1 inhibitors do not impair JAK2-dependent cytokine signaling and are inactive in cells expressing a C817A JAK1 mutant. Our findings thus reveal an allosteric approach for inhibiting JAK1 with unprecedented isoform selectivity.
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Cisteína , Proteómica , Transducción de Señal , Citocinas , Isoformas de ProteínasRESUMEN
Proteolysis is a key regulatory process that promotes the (in)activation, translocation, and/or degradation of proteins. As such, there is considerable interest in methods to comprehensively characterize proteolytic pathways in biological systems. Here, we describe a robust and versatile proteomic platform that enables direct visualization of the topography and magnitude of proteolytic events on a global scale. We use this method to generate a proteome-wide map of proteolytic events induced by the intrinsic apoptotic pathway. This profile contained 91 characterized caspase substrates as well as 170 additional proteins not previously known to be cleaved during apoptosis. Surprisingly, the vast majority of proteolyzed proteins, regardless of the extent of cleavage, yielded persistent fragments that correspond to discrete protein domains, suggesting that the generation of active effector proteins may be a principal function of apoptotic proteolytic cascades.
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Apoptosis , Péptido Hidrolasas/metabolismo , Proteínas/metabolismo , Proteómica/métodos , Humanos , Células Jurkat , Espectrometría de MasasRESUMEN
RATIONALE: Plaque rupture is the proximate cause of most myocardial infarctions and many strokes. However, the molecular mechanisms that precipitate plaque rupture are unknown. OBJECTIVE: By applying proteomic and bioinformatic approaches in mouse models of protease-induced plaque rupture and in ruptured human plaques, we aimed to illuminate biochemical pathways through which proteolysis causes plaque rupture and identify substrates that are cleaved in ruptured plaques. METHODS AND RESULTS: We performed shotgun proteomics analyses of aortas of transgenic mice with macrophage-specific overexpression of urokinase (SR-uPA+/0 mice) and of SR-uPA+/0 bone marrow transplant recipients, and we used bioinformatic tools to evaluate protein abundance and functional category enrichment in these aortas. In parallel, we performed shotgun proteomics and bioinformatics studies on extracts of ruptured and stable areas of freshly harvested human carotid plaques. We also applied a separate protein-analysis method (protein topography and migration analysis platform) to attempt to identify substrates and proteolytic fragments in mouse and human plaque extracts. Approximately 10% of extracted aortic proteins were reproducibly altered in SR-uPA+/0 aortas. Proteases, inflammatory signaling molecules, as well as proteins involved with cell adhesion, the cytoskeleton, and apoptosis, were increased. ECM (Extracellular matrix) proteins, including basement-membrane proteins, were decreased. Approximately 40% of proteins were altered in ruptured versus stable areas of human carotid plaques, including many of the same functional categories that were altered in SR-uPA+/0 aortas. Collagens were minimally altered in SR-uPA+/0 aortas and ruptured human plaques; however, several basement-membrane proteins were reduced in both SR-uPA+/0 aortas and ruptured human plaques. Protein topography and migration analysis platform did not detect robust increases in proteolytic fragments of ECM proteins in either setting. CONCLUSIONS: Parallel studies of SR-uPA+/0 mouse aortas and human plaques identify mechanisms that connect proteolysis with plaque rupture, including inflammation, basement-membrane protein loss, and apoptosis. Basement-membrane protein loss is a prominent feature of ruptured human plaques, suggesting a major role for basement-membrane proteins in maintaining plaque stability.
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Aorta/metabolismo , Enfermedades de la Aorta/metabolismo , Aterosclerosis/metabolismo , Arterias Carótidas/metabolismo , Placa Aterosclerótica , Proteoma , Proteómica , Anciano , Anciano de 80 o más Años , Animales , Aorta/patología , Enfermedades de la Aorta/genética , Enfermedades de la Aorta/patología , Aterosclerosis/genética , Aterosclerosis/patología , Arterias Carótidas/patología , Enfermedades de las Arterias Carótidas , Biología Computacional , Modelos Animales de Enfermedad , Femenino , Humanos , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados para ApoE , Persona de Mediana Edad , Mapas de Interacción de Proteínas , Receptores Depuradores/genética , Rotura Espontánea , Transducción de Señal , Activador de Plasminógeno de Tipo Uroquinasa/genética , Activador de Plasminógeno de Tipo Uroquinasa/metabolismoRESUMEN
Ligand-induced protein degradation has emerged as a compelling approach to promote the targeted elimination of proteins from cells by directing these proteins to the ubiquitin-proteasome machinery. So far, only a limited number of E3 ligases have been found to support ligand-induced protein degradation, reflecting a dearth of E3-binding compounds for proteolysis-targeting chimera (PROTAC) design. Here, we describe a functional screening strategy performed with a focused library of candidate electrophilic PROTACs to discover bifunctional compounds that degrade proteins in human cells by covalently engaging E3 ligases. Mechanistic studies revealed that the electrophilic PROTACs act through modifying specific cysteines in DCAF11, a poorly characterized E3 ligase substrate adaptor. We further show that DCAF11-directed electrophilic PROTACs can degrade multiple endogenous proteins, including FBKP12 and the androgen receptor, in human prostate cancer cells. Our findings designate DCAF11 as an E3 ligase capable of supporting ligand-induced protein degradation via electrophilic PROTACs.
Asunto(s)
Complejos de Ubiquitina-Proteína Ligasa/fisiología , Línea Celular Tumoral , Humanos , Masculino , Neoplasias de la Próstata/metabolismo , Neoplasias de la Próstata/patología , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , Receptores Androgénicos/metabolismo , Ubiquitina/metabolismo , Complejos de Ubiquitina-Proteína Ligasa/metabolismoRESUMEN
Phenotypic screening has identified small-molecule modulators of aging, but the mechanism of compound action often remains opaque due to the complexities of mapping protein targets in whole organisms. Here, we combine a library of covalent inhibitors with activity-based protein profiling to coordinately discover bioactive compounds and protein targets that extend lifespan in Caenorhabditis elegans. We identify JZL184-an inhibitor of the mammalian endocannabinoid (eCB) hydrolase monoacylglycerol lipase (MAGL or MGLL)-as a potent inducer of longevity, a result that was initially perplexing as C. elegans does not possess an MAGL ortholog. We instead identify FAAH-4 as a principal target of JZL184 and show that this enzyme, despite lacking homology with MAGL, performs the equivalent metabolic function of degrading eCB-related monoacylglycerides in C. elegans. Small-molecule phenotypic screening thus illuminates pure pharmacological connections marking convergent metabolic functions in distantly related organisms, implicating the FAAH-4/monoacylglyceride pathway as a regulator of lifespan in C. elegans.
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Benzodioxoles/farmacología , Caenorhabditis elegans/efectos de los fármacos , Endocannabinoides/antagonistas & inhibidores , Inhibidores Enzimáticos/farmacología , Longevidad/efectos de los fármacos , Monoacilglicerol Lipasas/antagonistas & inhibidores , Piperidinas/farmacología , Animales , Benzodioxoles/química , Caenorhabditis elegans/metabolismo , Endocannabinoides/metabolismo , Inhibidores Enzimáticos/química , Estructura Molecular , Monoacilglicerol Lipasas/metabolismo , Piperidinas/químicaRESUMEN
Monoacylglycerol lipase (MGLL) is the primary degradative enzyme for the endocannabinoid 2-arachidonoylglycerol (2-AG). The first MGLL inhibitors have recently entered clinical development for the treatment of neurologic disorders. To support this clinical path, we report the pharmacological characterization of the highly potent and selective MGLL inhibitor ABD-1970 [1,1,1,3,3,3-hexafluoropropan-2-yl 4-(2-(8-oxa-3-azabicyclo[3.2.1]octan-3-yl)-4-chlorobenzyl)piperazine-1-carboxylate]. We used ABD-1970 to confirm the role of MGLL in human systems and to define the relationship between MGLL target engagement, brain 2-AG concentrations, and efficacy. Because MGLL contributes to arachidonic acid metabolism in a subset of rodent tissues, we further used ABD-1970 to evaluate whether selective MGLL inhibition would affect prostanoid production in several human assays known to be sensitive to cyclooxygenase inhibitors. ABD-1970 robustly elevated brain 2-AG content and displayed antinociceptive and antipruritic activity in a battery of rodent models (ED50 values of 1-2 mg/kg). The antinociceptive effects of ABD-1970 were potentiated when combined with analgesic standards of care and occurred without overt cannabimimetic effects. ABD-1970 also blocked 2-AG hydrolysis in human brain tissue and elevated 2-AG content in human blood without affecting stimulated prostanoid production. These findings support the clinical development of MGLL inhibitors as a differentiated mechanism to treat pain and other neurologic disorders.
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Endocannabinoides/metabolismo , Inhibidores Enzimáticos/farmacología , Monoacilglicerol Lipasas/antagonistas & inhibidores , Analgésicos/farmacología , Animales , Antipruriginosos/farmacología , Ácidos Araquidónicos/metabolismo , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Línea Celular Tumoral , Inhibidores de la Ciclooxigenasa/farmacología , Glicéridos/metabolismo , Humanos , Hidrólisis/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos ICR , Células PC-3 , Dolor/tratamiento farmacológico , Dolor/metabolismo , Piperidinas/farmacología , Prostaglandinas/farmacología , Ratas , Ratas Sprague-Dawley , RoedoresRESUMEN
Cysteine is the most intrinsically nucleophilic amino acid in proteins, where its reactivity is tuned to perform diverse biochemical functions. The absence of a consensus sequence that defines functional cysteines in proteins has hindered their discovery and characterization. Here we describe a proteomics method to profile quantitatively the intrinsic reactivity of cysteine residues en masse directly in native biological systems. Hyper-reactivity was a rare feature among cysteines and it was found to specify a wide range of activities, including nucleophilic and reductive catalysis and sites of oxidative modification. Hyper-reactive cysteines were identified in several proteins of uncharacterized function, including a residue conserved across eukaryotic phylogeny that we show is required for yeast viability and is involved in iron-sulphur protein biogenesis. We also demonstrate that quantitative reactivity profiling can form the basis for screening and functional assignment of cysteines in computationally designed proteins, where it discriminated catalytically active from inactive cysteine hydrolase designs.
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Cisteína/metabolismo , Proteínas/química , Proteínas/metabolismo , Proteoma/química , Proteoma/metabolismo , Animales , Biocatálisis , Línea Celular Tumoral , Secuencia Conservada , Cisteína/análisis , Humanos , Hidrolasas/química , Hidrolasas/metabolismo , Proteínas Hierro-Azufre/biosíntesis , Hígado/metabolismo , Ratones , Miocardio/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Oxidación-Reducción , Ingeniería de Proteínas , Hidrolisados de Proteína , Proteína-Arginina N-Metiltransferasas/química , Proteína-Arginina N-Metiltransferasas/metabolismo , Proteómica/métodos , Proteínas Represoras/química , Proteínas Represoras/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMEN
N-Acyl phospholipids are atypical components of cell membranes that bear three acyl chains and serve as potential biosynthetic precursors for lipid mediators such as endocannabinoids. Biochemical studies have implicated ABHD4 as a brain N-acyl phosphatidylethanolamine (NAPE) lipase, but in vivo evidence for this functional assignment is lacking. Here, we describe ABHD4(-/-) mice and their characterization using untargeted lipidomics to discover that ABHD4 regulates multiple classes of brain N-acyl phospholipids. In addition to showing reductions in brain glycerophospho-NAEs (GP-NAEs) and plasmalogen-based lyso-NAPEs (lyso-pNAPEs), ABHD4(-/-) mice exhibited decreases in a distinct set of brain lipids that were structurally characterized as N-acyl lysophosphatidylserines (lyso-NAPSs). Biochemical assays confirmed that NAPS lipids are direct substrates of ABHD4. These findings, taken together, designate ABHD4 as a principal regulator of N-acyl phospholipid metabolism in the mammalian nervous system.
Asunto(s)
Química Encefálica/fisiología , Encéfalo/metabolismo , Lisofosfolipasa/metabolismo , Fosfatidiletanolaminas/metabolismo , Animales , Lisofosfolipasa/clasificación , Lisofosfolipasa/genética , Ratones , Ratones Noqueados , Fosfatidiletanolaminas/genéticaRESUMEN
The gut microbiota influences numerous aspects of human biology. One facet that has not been thoroughly explored is its impact on the host proteome. We hypothesized that the microbiota may produce certain of its effects through covalent modification of host proteins. We focused on protein lysine ε-acetylation because of its recently discovered roles in regulation of cell metabolism, and the potential for products of microbial fermentation to interact with the lysine acetylation machinery of host cells. Germ-free mice, fed a (15)N-labeled diet for two generations, were colonized as adults with a microbiota harvested from conventionally raised mouse donors. Using high-resolution mass spectrometry, we quantified 3,891 liver and proximal colonic proteins, 558 of which contained 1,602 sites of lysine acetylation, 43% not previously described. Multiple proteins from multiple subcellular compartments underwent microbiota-associated increases in their levels of lysine acetylation at one or more residues, in one or both tissues. Acetylated proteins were enriched in functions related to energy production, respiration, and primary metabolism. A number of the acetylation events affect lysine residues at or near the active sites of enzymes, whereas others occur at locations that may affect other facets of protein function. One of these modifications, affecting Lys292 in mouse α-1-antitrypsin, was detected in the corresponding lysine of the human serum protein. Methods described in this report can be applied to other co- or posttranslational modifications, and add quantitation of protein expression and covalent modification to the arsenal of techniques for characterizing the dynamic, important interactions between gut symbionts and their hosts.
Asunto(s)
Vida Libre de Gérmenes , Intestinos/microbiología , Metagenoma , Acetilación , Animales , Colon/metabolismo , Cianobacterias/metabolismo , Femenino , Fermentación , Humanos , Hígado/metabolismo , Lisina/química , Masculino , Espectrometría de Masas/métodos , Ratones , Ratones Endogámicos C57BLRESUMEN
Covalent chemistry is a versatile approach for expanding the ligandability of the human proteome. Activity-based protein profiling (ABPP) can infer the specific residues modified by electrophilic compounds through competition with broadly reactive probes. However, the extent to which such residue-directed platforms fully assess the protein targets of electrophilic compounds in cells remains unclear. Here we evaluate a complementary protein-directed ABPP method that identifies proteins showing stereoselective reactivity with alkynylated, chiral electrophilic compounds-termed stereoprobes. Integration of protein- and cysteine-directed data from cancer cells treated with tryptoline acrylamide stereoprobes revealed generally well-correlated ligandability maps and highlighted features, such as protein size and the proteotypicity of cysteine-containing peptides, that explain gaps in each ABPP platform. In total, we identified stereoprobe binding events for >300 structurally and functionally diverse proteins, including compounds that stereoselectively and site-specifically disrupt MAD2L1BP interactions with the spindle assembly checkpoint complex leading to delayed mitotic exit in cancer cells.
RESUMEN
In the past decade, there have been remarkable advances in proteomic technologies. Mass spectrometry has emerged as the preferred method for in-depth characterization of the protein components of biological systems. Using mass spectrometry, key insights into the composition, regulation and function of molecular complexes and pathways have been gained. From these studies, it is clear that mass-spectrometry-based proteomics is now a powerful 'hypothesis-generating engine' that, when combined with complementary molecular, cellular and pharmacological techniques, provides a framework for translating large data sets into an understanding of complex biological processes.