Modification Of Specific Proteins Research Articles

Plant U-box E3 ligase PpPUB59 regulates anthocyanin accumulation by ubiquitinating PpBBX24 in ‘Zaosu’ pear and its red bud mutation

Ubiquitination is the specific modification of target proteins in cells by ubiquitin molecules, which is under the action of a series of special enzymes such as ubiquitin-activating enzymes, binding, and ligase enzymes. Ubiquitination plays an essential role in anthocyanin accumulation in plants. There are few studies on the coloring of pear peel by ubiquitin ligase E3. In this study, an E3 ubiquitin ligase protein PpPUB59 with seven WD40 repeats was cloned. And the function of PpPUB59 on the ubiquitination and protein stability of PpBBX24 and Ppbbx24-del, and the possible action mechanism in the anthocyanin accumulation of ‘Red Zaosu’ was studied. Our results showed that the WD40 repeats were verified to be the key domain interacting with the VP domain of BBX protein. PpPUB59 could degrade PpBBX24 in vitro by interacting with the VP domain but could not degrade the mutant PpBBX24-del without the VP domain. Dual luciferase assay showed that Ppbbx24-del could activate the PpCHS promoter, while PpPUB59 did not interfere with this activation; PpBBX24 could not activate the promotor of PpCHS but could suppress the activation of PpHY5; when the PpPUB59 was co-expressed with PpBBX24 and PpHY5, the activation roles of PpHY5 in the promotor of PpCHS was not recovered. BiFC and yeast two-hybrid experiments showed that PpPUB59 could also interact with PpHY5, which may make it ubiquitinated and degraded by 26S proteasome. In conclusion, PpPUB59 played an essential role in pear anthocyanin accumulation by ubiquitinating the associated transcription factors. These findings clarified the mutant mechanism of the ‘Red Zaosu’ pear at the post-translational modification level and enriched the regulation theory of the pear anthocyanin accumulation.

SITP: A single cell bioinformatics analysis flow captures proteasome markers in the development of breast cancer

Single cell sequencing and related databases have been widely used in the exploration of cancer occurrence and development, but there is still no in-depth explanation of specific and complicated cellular protein modification processes. Ubiquitin-Proteasome System (UPS), as a specific and precise protein modification and degradation process, plays an important role in the biological functions of cancer cell proliferation and apoptosis. Proteasomes, vital multi-catalytic proteinases in eukaryotic cells, play a crucial role in protein degradation and contribute to tumor regulation. The 26S proteasome, part of the ubiquitin–proteasome system. In this study, we have enrolled a common SITP process including analysis of single cell sequencing to elucidate a flow that can capture typical proteasome markers in the oncogenesis and progression of breast cancer. PSMD11, a key component of the 26S proteasome regulatory particle, has been identified as a critical survival factor in cancer cells. Results suggest that PSMD11’s rapid degradation is linked to acute apoptosis in cancer cells, making it a potential target for cancer treatment. Our study explored the potential mechanisms of PSMD11 in breast cancer development. The findings revealed the feasibility of disclosing ubiquitinating biomarkers from public database, as well as presented new evidence supporting PSMD11 as a potential therapeutic biomarker for breast cancer.

Train and Reprogram Your Brain: Effects of Physical Exercise at Different Stages of Life on Brain Functions Saved in Epigenetic Modifications.

Multiple studies have demonstrated the significant effects of physical exercise on brain plasticity, the enhancement of memory and cognition, and mood improvement. Although the beneficial impact of exercise on brain functions and mental health is well established, the exact mechanisms underlying this phenomenon are currently under thorough investigation. Several hypotheses have emerged suggesting various possible mechanisms, including the effects of hormones, neurotrophins, neurotransmitters, and more recently also other compounds such as lactate or irisin, which are released under the exercise circumstances and act both locally or/and on distant tissues, triggering systemic body reactions. Nevertheless, none of these actually explain the long-lasting effect of exercise, which can persist for years or even be passed on to subsequent generations. It is believed that these long-lasting effects are mediated through epigenetic modifications, influencing the expression of particular genes and the translation and modification of specific proteins. This review explores the impact of regular physical exercise on brain function and brain plasticity and the associated occurrence of epigenetic modifications. It examines how these changes contribute to the prevention and treatment of neuropsychiatric and neurological disorders, as well as their influence on the natural aging process and mental health.

Multiplexed chromatin immunoprecipitation sequencing for quantitative study of histone modifications and chromatin factors.

ChIP-seq is a widely used technique for studying histone post-translational modifications and DNA-binding proteins. DNA fragments associated with a specific protein or histone modification epitope are captured by using antibodies, sequenced and mapped to a reference genome. Albeit versatile and popular, performing many parallel ChIP-seq experiments to compare different conditions, replicates and epitopes is laborious, is prone to experimental variation and does not allow quantitative comparisons unless adequate spike-in chromatin is included. We present a detailed protocol for performing and analyzing a multiplexed quantitative chromatin immunoprecipitation-sequencing experiment (MINUTE-ChIP), in which multiple samples are profiled against multiple epitopes in a single workflow. Multiplexing not only dramatically increases the throughput of ChIP-seq experiments (e.g., profiling 12 samples against multiple histone modifications or DNA-binding proteins in a single experiment), but also enables accurate quantitative comparisons. The protocol consists of four parts: sample preparation (i.e., lysis, chromatin fragmentation and barcoding of native or formaldehyde-fixed material), pooling and splitting of the barcoded chromatin into parallel immunoprecipitation reactions, preparation of next-generation sequencing libraries from input and immunoprecipitated DNA and data analysis using our dedicated analysis pipeline. This pipeline autonomously generates quantitatively scaled ChIP-seq tracks for downstream analysis and visualization, alongside necessary quality control indicators. The entire workflow requires basic knowledge in molecular biology and bioinformatics and can be completed in 1 week. MINUTE-ChIP empowers biologists to perform every ChIP-seq experiment with an appropriate number of replicates and control conditions, delivering more statistically robust, exquisitely quantitative and biologically meaningful results.

Ubiquitination and deubiquitination in the regulation of N6-methyladenosine functional molecules.

N6 methyladenosine (m6A) is the most prevalent RNA epigenetic modification, regulated by methyltransferases and demethyltransferases and recognized by methylation-related reading proteins to impact mRNA splicing, translocation, stability, and translation efficiency. It significantly affects a variety of activities, including stem cell maintenance and differentiation, tumor formation, immune regulation, and metabolic disorders. Ubiquitination refers to the specific modification of target proteins by ubiquitin molecule in response to a series of enzymes. E3 ligases connect ubiquitin to target proteins and usually lead to protein degradation. On the contrary, deubiquitination induced by deubiquitinating enzymes (DUBs) can separate ubiquitin and regulate the stability of protein. Recent studies have emphasized the potential importance of ubiquitination and deubiquitination in controlling the function of m6A modification. In this review, we discuss the impact of ubiquitination and deubiquitination on m6A functional molecules in diseases, such as metabolism, cellular stress, and tumor growth.

Polyamine-Derived Aminoaldehydes and Acrolein: Cytotoxicity, Reactivity and Analysis of the Induced Protein Modifications.

Polyamines participate in the processes of cell growth and development. The degradation branch of their metabolism involves amine oxidases. The oxidation of spermine, spermidine and putrescine releases hydrogen peroxide and the corresponding aminoaldehyde. Polyamine-derived aminoaldehydes have been found to be cytotoxic, and they represent the subject of this review. 3-aminopropanal disrupts the lysosomal membrane and triggers apoptosis or necrosis in the damaged cells. It is implicated in the pathogenesis of cerebral ischemia. Furthermore, 3-aminopropanal yields acrolein through the elimination of ammonia. This reactive aldehyde is also generated by the decomposition of aminoaldehydes produced in the reaction of serum amine oxidase with spermidine or spermine. In addition, acrolein is a common environmental pollutant. It causes covalent modifications of proteins, including carbonylation, the production of Michael-type adducts and cross-linking, and it has been associated with inflammation-related diseases. APAL and acrolein are detoxified by aldehyde dehydrogenases and other mechanisms. High-performance liquid chromatography, immunochemistry and mass spectrometry have been largely used to analyze the presence of polyamine-derived aminoaldehydes and protein modifications elicited by their effect. However, the main and still open challenge is to find clues for discovering clear linkages between aldehyde-induced modifications of specific proteins and the development of various diseases.

Proteome-wide identification of S-sulfenylated cysteines response to salt stress in Brassica napus root

Reactive oxygen species (ROS) play a key role in a variety of biological processes, such as the perception of abiotic stress, the integration of different environmental signals, and the activation of stress response networks. Salt stress could induce an increased ROS accumulation in plants, disrupting intracellular redox homeostasis, leading to post-translational modifications (PTMs) of specific proteins, and eventually causing adaptive changes in metabolism. Here, we performed an iodoTMT-based proteomic approach to identify the sulfenylated proteins in B. napus root responsing to salt stress. Totally, 1 348 sulfenylated sites in 751 proteins were identified and these proteins were widely existed in different cell compartments and processes. Our study revealed that proteins with changed abundance and sulfenylation level in B. napus root under salt stress were mainly enriched in the biological processes of ion binding, glycolysis, ATP binding, and oxidative stress response. This study displays a landscape of sulfenylated proteins response to salt stress in B. napus root and provides some theoretical support for further understanding of the molecular mechanisms of redox regulation under salt stress in plants.

Reverse-QTY code design of active human serum albumin self-assembled amphiphilic nanoparticles for effective anti-tumor drug doxorubicin release in mice

Human serum albumin (HSA) is a highly water-soluble protein with 67% alpha-helix content and three distinct domains (I, II, and III). HSA offers a great promise in drug delivery with enhanced permeability and retention effect. But it is hindered by protein denaturation during drug entrapment or conjugation that result in distinct cellular transport pathways and reduction of biological activities. Here we report using a protein design approach named reverse-QTY (rQTY) code to convert specific hydrophilic alpha-helices to hydrophobic to alpha-helices. The designed HSA undergo self-assembly of well-ordered nanoparticles with highly biological actives. The hydrophilic amino acids, asparagine (N), glutamine (Q), threonine (T), and tyrosine (Y) in the helical B-subdomains of HSA were systematically replaced by hydrophobic leucine (L), valine (V), and phenylalanine (F). HSArQTY nanoparticles exhibited efficient cellular internalization through the cell membrane albumin binding protein GP60, or SPARC (secreted protein, acidic and rich in cysteine)-mediated pathways. The designed HSArQTY variants displayed superior biological activities including: i) encapsulation of drug doxorubicin, ii) receptor-mediated cellular transport, iii) tumor cell targeting, and iv) antitumor efficiency compare to denatured HSA nanoparticles. HSArQTY nanoparticles provided superior tumor targeting and antitumor therapeutic effects compared to the albumin nanoparticles fabricated by antisolvent precipitation method. We believe that the rQTY code is a robust platform for specific hydrophobic modification of functional hydrophilic proteins with clear-defined binding interfaces.

Mechanisms of TRAF3 regulation of TLR signaling in B lymphocytes

Abstract Toll-like receptors (TLRs) are pattern recognition receptors that bridge the innate and adaptive immune system and are critical for host defense. TLR signaling to B cells is important in normal immunity, but also implicated in autoimmune disease and B cell lymphomas (BCL). Most studies focus on the role of TLRs in myeloid cell populations. However, B cells express most TLRs and are highly responsive to TLR ligands, yet TLR-mediated B cell pathways are understudied. Previous studies from our lab show that TRAF3 inhibits B cell TLR functions, including cytokine production, Ig isotype switching, and antibody production in response to ligands for TLRs 3, 4, 7/8 and 9. A key knowledge gapis identifying the molecular mechanisms by which TRAF3 mediates this regulation. Our working hypothesisis that B cell-TRAF3 regulates the recruitment and/or post-translational modification of specific TLR complex signaling proteins. Our recent data show that B cell-TRAF3 forms a heterocomplex with TRAF6, associating with the tyrosine kinase Syk. In the absence of TRAF3, TRAF6 shows a greater association with several TLR signaling proteins, including MyD88, IRAK1 and Syk. This suggests that TRAF3 may inhibit TRAF6 access to the TLR signaling complex, and thus early TLR signaling. In addition, our work introduces a role for Syk in TLR signaling in B cells. In the absence of TRAF3, activation of Syk is enhanced in response to ligands for TLRs 4 and 7. Inhibition of Syk activation also revealed downstream effects on TLR-mediated NFκB activation. Further studies aim at providing new insights into molecular mechanisms contributing to the regulation of B cell-TRAF3 in TLR signaling. VA Merit Review I01 BX001702 NIH P50 CA97274 RO1 AI5107312000000113259002001 NIH T32 Training Grant AI07485 RO1 AI1762656

MTNA: A deep learning based predictor for identifying multiple types of N-terminal protein acetylated sites

<abstract> <p>N-terminal acetylation is a specific protein modification that occurs only at the N-terminus but plays a significant role in protein stability, folding, subcellular localization and protein-protein interactions. Computational methods enable finding N-terminal acetylated sites from large-scale proteins efficiently. However, limited by the number of the labeled proteins, existing tools only focus on certain subtypes of N-terminal acetylated sites on frequently detected amino acids. For example, NetAcet focuses on alanine, glycine, serine and threonine only, and N-Ace predicts on alanine, glycine, methionine, serine and threonine. With the growth of experimental N-terminal acetylated site data, it is observed that N-terminal protein acetylation occurs on nearly ten types of amino acids. To facilitate comprehensive analysis, we have developed MTNA (Multiple Types of N-terminal Acetylation), a deep learning network capable of accurately predicting N-terminal protein acetylation sites for various amino acids at the N-terminus. MTNA not only outperforms existing tools but also has the capability to identify rare types of N-terminal protein acetylated sites occurring on less studied amino acids.</p> </abstract>

Brain O-GlcNAcylation: From Molecular Mechanisms to Clinical Phenotype.

O-GlcNAc is the attachment of β-N-acetylglucosamine to the hydroxyl group of serine and threonine in nuclear and cytoplasmic proteins. It is generally not further elongated but exists as a monosaccharide that can be rapidly added or removed. Thousands of proteins involved in gene transcription, protein translation and degradation as well as the regulation of signal transduction contain O-GlcNAc. Brain is one of the tissues where O-GlcNAc is the most highly expressed and deletion of neuronal O-GlcNAc leads to death early in development. O-GlcNAc is also important for normal adult brain function, where dynamic processes like learning and memory at least in part depend on the modification of specific proteins by O-GlcNAc. Conversely, too much or too little O-GlcNAc in the brain contributes to several disorders including obesity, intellectual disability and Alzheimer's disease. In this chapter, we describe the expression and regulation of O-GlcNAc in the nervous system.

Factors affecting the modification of bovine milk proteins in high hydrostatic pressure processing: An updated review.

High hydrostatic pressure (HHP) treatment induces structural changes in bovine milk proteins depending on factors such as the temperature, pH, concentration, decompression rate, cycling, composition of the medium and pressure level and duration. An in-depth understanding of the impact of these factors is important for controlling HHP-induced modification of milk proteins and the interactions within or between them, which can be applied to prevent undesired aggregation, gelation, and precipitation during HHP processing or to obtain specific milk protein modifications to attain specific protein properties. In this regard, understanding the influences of these factors can provide insight into the modulation and optimization of HHP conditions to attain specific milk protein structures. In recent years, there has been a great research attention on HHP-induced changes in milk proteins influenced by factors such as pH, temperature, concentration, cycling, decompression condition, and medium composition. Hence, to provide insight into how these factors control milk protein structures under HHP treatment and to understand if their effects depend on HHP parameters and environmental conditions, this review discusses recent findings on how various factors (pH, temperature, cycling, decompression rate, medium composition, and concentration) affect HHP-induced bovine milk protein modification. Practical Application: The information provided in this review will be very useful to anticipate the challenges related to the formulation and development of pressure-treated milk and dairy products.

MO185: Post-Translational Carbamylation of Sortilin is Associated with Cardiovascular Calcification in Chronic Kidney Disease

Abstract BACKGROUND AND AIMS Sortilin, an intracellular sorting receptor, has been identified as a cardiovascular (CV) risk factor in the general population. Patients with chronic kidney disease (CKD) are highly susceptible to developing CV complications such as CV calcification. However, specific CKD-induced post-translational protein modifications of sortilin and their link to CV calcification remain unknown. METHODS Circulating sortilin isolated from two independent CKD cohorts was analysed by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/TOF mass spectrometry). The binding partner affinity was analysed by surface plasmon resonance spectroscopy. The effect of carbamylated sortilin on vascular calcification was analysed in vitro using human coronary artery smooth muscle cells. RESULTS In CKD patients, targeted mass spectrometric analyses of circulating sortilin revealed an increase in carbamylated lysine residues with kidney function decline. Carbamylation did not affect dimer formation of sortilin assessed by mass spectrometry. We observed an increased affinity of interleukin 6 to in vitro carbamylated sortilin. Carbamylated sortilin increased SMC calcification in vitro that was accelerated by interleukin 6, while carbamylated albumin and collagen type I did not affect SMC calcification. Mass-spectrometry imaging of human calcified arteries revealed in situ carbamylated sortilin. In CKD patients, sortilin carbamylation was associated with coronary artery calcification volume, independent of age, kidney function and other risk factors. Moreover, patients with carbamylated sortilin displayed significantly faster coronary artery calcification progression than patients without sortilin carbamylation. CONCLUSION Carbamylated sortilin is a risk factor for CV calcification and may contribute to elevated CV complications in patients with CKD.

Mechanisms of TRAF3 regulation of TLR signaling in B lymphocytes

Abstract TRAF3 is an adaptor protein that binds to a variety of receptor types on immune cells and exerts multiple regulatory functions in signaling pathways. TRAF3 functions are cell type and context dependent. B cell-TRAF3 inhibits homeostatic NFκB2 activation and other pro-survival signaling pathways; restraint of survival is a B cell-unique TRAF3 function. Loss of B cell-TRAF3 in vivo contributes to early autoimmunity and later lymphomagenesis. TRAF3 inhibits B cell TLR functions, including cytokine production (IL-6, IL-10, IL-12p40 and TNFα), Ig isotype switching, and antibody production in response to ligands for TLRs 3, 4, 7/8 and 9. A key knowledge gap is identifying the molecular mechanisms by which TRAF3 mediates this regulation. Our working hypothesis is that B cell-TRAF3 regulates the activity, recruitment, and/or post-translational modification of specific TLR signaling proteins. Our recent data show that B cell-TRAF3 forms a heterocomplex with TRAF6, associating with the tyrosine kinase Syk and inhibiting early TLR signals, such as pIRAK1 degradation. In the absence of TRAF3, TRAF6 shows a greater association with several TLR signaling proteins. These results suggest that TRAF3 may inhibit TRAF6 access to the TLR signaling complex, and thus early TLR signaling. Further studies aimed at providing new insights into the molecular mechanisms contributing to the regulation of B cell-TRAF3 in TLR signaling can inform selection and development of more targeted therapies for B cell malignancies and autoimmunity. Supported by VA Merit Review IO1 BX001702 NIH RO1 AI62656 NIH P50 CA97274 NIH T32 Training Grant AI07485

Selective detection of protein acetylation by NMR spectroscopy

Selective detection of biomolecules and their modifications in cells is essential for understanding cell functions and diseases. We have developed an NMR pulse sequence, Ac-FIND (Acetylation-FIltered aNd eDited), which uses isotope editing/filtering techniques for selective detection of protein acetylation. Acetylation of the N-terminus and lysine side chains by N-succinimidyl acetate was selectively observed for intrinsically disordered α-synuclein and well-ordered ubiquitin. Furthermore, when nonacetylated 13C/15N-enriched α-synuclein was introduced into live HEK293 cells, intracellular N-terminal acetylation of α-synuclein was detected by the appearance of a single peak using Ac-FIND. This work demonstrates the utility of NMR to detect a specific protein modification both in vitro and in live cells.

EXECUTER2 modulates the EXECUTER1 signalosome through its singlet oxygen-dependent oxidation

Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling. The Arabidopsis thaliana EXECUTER1 (EX1) protein, a chloroplast-localized singlet oxygen (1O2) sensor, undergoes tryptophan (Trp) 643 oxidation by 1O2, a chloroplast-derived and light-dependent reactive oxygen species. The indole side chain of Trp is vulnerable to 1O2, leading to the generation of oxidized Trp variants and priming EX1 for degradation by a membrane-bound FtsH protease. The perception of 1O2 via Trp643 oxidation and subsequent EX1 proteolysis facilitate chloroplast-to-nucleus retrograde signaling. In this study, we discovered that the EX1-like protein EX2 also undergoes 1O2-dependent Trp530 oxidation and FtsH-dependent turnover, which attenuates 1O2 signaling by decelerating EX1-Trp643 oxidation and subsequent EX1 degradation. Consistent with this finding, the loss of EX2 function reinforces EX1-dependent retrograde signaling by accelerating EX1-Trp643 oxidation and subsequent EX1 proteolysis, whereas overexpression of EX2 produces molecular phenotypes opposite to those observed in the loss–of- function mutants of EX2. Intriguingly, phylogenetic analysis suggests that EX2 may have emerged evolutionarily to attenuate the sensitivity of EX1 toward 1O2. Collectively, these results suggest that EX2 functions as a negative regulator of the EX1 signalosome through its own 1O2-dependent oxidation, providing a new mechanistic insight into the regulation of EX1-mediated 1O2 signaling.

S-nitrosothiols signaling in cystic fibrosis airways

S-nitrosothiols (SNOs) are small naturally occurring thiol and nitric oxide adducts that participate in many cell signaling pathways in living organisms. SNOs receive widespread attention in cell biology, biochemistry and chemistry because they can donate nitric oxide and/or nitrosonium ions in S-nitrosylation reactions, which are comparable to phosphorylation, acetylation, glutathionylation, and palmitoylation reactions. SNOs have advantageous effects in respiratory diseases and other systems in the body. S-nitrosylation signaling is a metabolically regulated physiological process that leads to specific post-translational protein modifications. S-nitrosylation signaling is faulty in cystic fibrosis (CF) and many other lung diseases. CF is an inherited, lethal autosomal recessive multisystem disease resulting from mutations in the gene encoding the CF transmembrane conductance regulatory (CFTR) protein. F508del CFTR is the most common mutation associated with CF, which results in CFTR misfolding because a phenylalanine is deleted from the primary structure of CFTR. The majority of wild-type CFTR and almost all F508del is degraded before reaching the cell surface. Ultimately, CF researchers have been looking to correct the mutated CFTR protein in the CF patients. Remarkably, researchers have found that SNOs levels are low in the CF lower airway compared to non-CF patients. We have been interested in determining whether SNOs increase CFTR maturation through S-nitrosylation. Maturation of both wild type and mutant F508del CFTR increases SNOs, which up-regulate CFTR maturation. In this review, we summarized our current knowledge of S-nitrosothiols signaling in cystic fibrosis airways.

Carbamylated sortilin associates with cardiovascular calcification in patients with chronic kidney disease

Sortilin, an intracellular sorting receptor, has been identified as a cardiovascular risk factor in the general population. Patients with chronic kidney disease (CKD) are highly susceptible to develop cardiovascular complications such as calcification. However, specific CKD-induced posttranslational protein modifications of sortilin and their link to cardiovascular calcification remain unknown. To investigate this, we examined two independent CKD cohorts for carbamylation of circulating sortilin and detected increased carbamylated sortilin lysine residues in the extracellular domain of sortilin with kidney function decline using targeted mass spectrometry. Structure analysis predicted altered ligand binding by carbamylated sortilin, which was verified by binding studies using surface plasmon resonance measurement, showing an increased affinity of interleukin 6 to invitro carbamylated sortilin. Further, carbamylated sortilin increased vascular calcification invitro and exvivo that was accelerated by interleukin 6. Imaging by mass spectrometry of human calcified arteries revealed in situ carbamylated sortilin. In patients with CKD, sortilin carbamylation was associated with coronary artery calcification, independent of age and kidney function. Moreover, patients with carbamylated sortilin displayed significantly faster progression of coronary artery calcification than patients without sortilin carbamylation. Thus, carbamylated sortilin may be a risk factor for cardiovascular calcification and may contribute to elevated cardiovascular complications in patients with CKD.

Protein Labeling and Crosslinking by Covalent Aptamers.

We developed a new approach to selectively modify native proteins in their biological environment using electrophilic covalent aptamers. These aptamers are generated through introduction of a proximity-driven electrophile at specific nucleotide sites. Using thrombin as a proof-of-concept, we demonstrate that covalent aptamers can selectively transfer a variety of functional handles and/or irreversibly crosslink to the target protein. This approach offers broad programmability and high target specificity. Furthermore, it addresses issues common to aptamers such as instability towards endogenous nucleases and residence times during target engagement. Covalent aptamers are new tools that enable specific protein modification and sensitive protein detection. Moreover, they provide prolonged, nuclease-resistant enzyme inhibition.

Protein Labeling and Crosslinking by Covalent Aptamers

AbstractWe developed a new approach to selectively modify native proteins in their biological environment using electrophilic covalent aptamers. These aptamers are generated through introduction of a proximity‐driven electrophile at specific nucleotide sites. Using thrombin as a proof‐of‐concept, we demonstrate that covalent aptamers can selectively transfer a variety of functional handles and/or irreversibly crosslink to the target protein. This approach offers broad programmability and high target specificity. Furthermore, it addresses issues common to aptamers such as instability towards endogenous nucleases and residence times during target engagement. Covalent aptamers are new tools that enable specific protein modification and sensitive protein detection. Moreover, they provide prolonged, nuclease‐resistant enzyme inhibition.