RSC Chemical Biology最新文献

{"title":"Participation of redox-active residues in polysaccharide monooxygenase catalysis.","authors":"Allison E Batka, Aneesh Bhat, Alexander J Rose, Michael A Marletta","doi":"10.1039/d6cb00144k","DOIUrl":"10.1039/d6cb00144k","url":null,"abstract":"<p><p>Polysaccharide monooxygenases (PMOs) degrade carbohydrate polymers <i>via</i> an oxidative mechanism involving activation of O₂ or H₂O₂ at a mononuclear copper active site. The reaction with O₂ requires the timely delivery of two electrons to the copper during each catalytic cycle. Large polymeric substrates might occlude the active site from reductant access, which raises questions of whether the substrate stays associated with the PMO during catalysis and whether there is an alternate path for electrons to reach the active site. Previous work provided evidence for electron transfer through residues Y168 (the axial tyrosine) and Y62 in an AA9 PMO, <i>Mt</i>PMO9E. Results reported here further investigate these redox-active residues by comparing the Y62F/Y168F double variant (2F) to the wild-type (WT) enzyme. Oxidase activity and oxygenase activity were compared using three different reductants: cysteine, ascorbate, and cellobiose dehydrogenase. Unlike cysteine and ascorbate, cellobiose dehydrogenase is comparatively large and thought to be the native electron donor to fungal PMOs. The oxidase and oxygenase activities of 2F are significantly decreased compared to WT, but the peroxygenase activity is unaffected. The slow oxygenase activity of 2F suggests the PMO is preferentially reduced <i>via</i> the redox-active residues, although some reduction may occur directly at the active site when the substrate is present. Engineering tyrosine residues into an AA9 PMO that natively lacks the redox-active residues increases oxidase activity. The oxygenase reaction is first-order in the reductant, suggesting the rate-limiting step involves electron transfer between the reductant and the redox-active residues. These observations underscore the importance of redox-active residues in O₂ utilization by PMOs.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"2069-2079"},"PeriodicalIF":3.9,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13462859/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148722223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-specific cysteine modifications on proteins induced by <i>trans</i>-cyclooctene.","authors":"Zhijian Yan, Wei Qin","doi":"10.1039/d6cb00166a","DOIUrl":"10.1039/d6cb00166a","url":null,"abstract":"<p><p>Tetrazine-<i>trans</i>-cyclooctene (Tz-TCO) click chemistry has been widely adopted for various applications due to its faster reaction kinetics and higher biocompatibility compared to conventional copper-catalyzed click chemistry. However, most click chemistry groups do not appear to be fully bioorthogonal, as several of them-including tetrazine-have been found to directly modify proteins. Here, we report the unexpected discovery of non-specific protein modifications by TCO during the development of a tetrazine-based proximity labeling method. TCO probes readily conjugate to cysteine residues on proteins, and pre-treatment with iodoacetamide significantly reduces TCO-mediated background labeling. Chemoproteomic analyses reveal that proteins involved in translation are heavily modified by TCO, pointing to potential off-target effects when TCO probes are used in live cells. Our findings underscore the need for further improving the biocompatibility of click chemistry to enable more precise biological applications.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"1724-1729"},"PeriodicalIF":3.9,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13455793/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148707891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proteome-wide target profiling of α-helix mimetics.","authors":"Amrita Date, Archie Wall, Hannah Kiely-Collins, Theo Flack, Jack W Houghton, Jianan Lu, Adam M Thomas, Peiyu Zhang, Andrew J Wilson, Edward W Tate, Anna Barnard","doi":"10.1039/d6cb00065g","DOIUrl":"10.1039/d6cb00065g","url":null,"abstract":"<p><p>The dysregulation of protein-protein interactions (PPIs) in disease states is well established, yet they are challenging to target, owing to the large surface area and featureless nature of protein binding interfaces. For targeting helix-mediated interactions, α-helix mimetics present a promising strategy. These are versatile small molecule scaffolds, capable of mimicking the hotspot residues on an α-helix. A wide range of such scaffolds have been reported, yet their target protein selectivity in the context of a whole proteome requires further exploration. Here, we report the affinity-based protein profiling of three structurally distinct classes of α-helix mimetics, <i>N</i>-substituted oligobenzamides, pyrrolopyrimidines, and oxopiperazines. This represents the first direct cross-comparison of different helix mimetic scaffolds, revealing significant differences in proteome-wide selectivity.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"1818-1827"},"PeriodicalIF":3.9,"publicationDate":"2026-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13417162/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148621789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ant abaecin-2 is a context-dependent copper-binding effector that can be either inhibitory or protective.","authors":"Caroline M Donaghy, Helena V Heyer-Gray, Charlotte O'Hern, Michael Ibrahim, Bryant Perez-Torres, Nichali Bogues, Andrei T Alexandrescu, Karrera Y Djoko, Jonathan L Klassen, Alfredo M Angeles-Boza","doi":"10.1039/d6cb00146g","DOIUrl":"10.1039/d6cb00146g","url":null,"abstract":"<p><p>Host defense peptides (HDPs) are important components of the innate immune system that are used to combat pathogens and often rely on binding trace nutrient metals for their function. However, controlling nutrient metals may have other roles in host-symbiont interactions beyond poisoning harmful pathogens. This study characterizes the evolution, structural properties, and biochemical activity of the novel hymenopteran HDP abaecin-2. In myrmicine ants such as the fungus-growing tribe Attini, abaecin-2 has evolved to include an Amino-Terminal Cu(ii) and Ni(ii)-binding (ATCUN) motif, which we hypothesize binds copper, a trace nutrient that is enriched in attine ant colonies. Combined results from mass spectrometry, competitive binding assays, circular dichroism, and NMR indicate that the abaecin-2 peptide lacks a defined secondary structure and can associate with up to 2 Cu(ii) ions, one strongly bound at the ATCUN motif and another weakly bound, likely at a conserved histidine residue. Despite its copper-binding activity, abaecin-2 alone does not exhibit antibacterial activity against <i>Escherichia coli</i> or <i>Bacillus subtilis</i> (models for bacteria that live in ant fungus gardens). However, it synergizes with a model pore-forming peptide cecropin A to inhibit the growth of <i>E. coli</i>, similar to the related peptide abaecin-1. The copper-binding activity conferred by the ATCUN motif also protects copper-sensitive <i>E. coli</i> from excess copper toxicity. The dual context-dependent inhibitory and protective roles for abaecin-2 indicate that this previously under-characterized HDP may be used by attine ants to regulate both harmful and beneficial symbionts.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"1804-1817"},"PeriodicalIF":3.9,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13398410/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Amidine isosteric modification tunes proteolytic stability and activity.","authors":"Jacob Byerly-Duke, Sarah M Bernhard, Rida Ibrahim, Sayan Das, Krishna K Sharma, Chinmaya Panda, Vincenzo Venditti, Tao Che, Brett VanVeller","doi":"10.1039/d6cb00138f","DOIUrl":"10.1039/d6cb00138f","url":null,"abstract":"<p><p>The therapeutic potential of peptides is severely limited by rapid metabolism mediated by proteases. Traditional stabilization strategies often compromise pharmacological profiles by disrupting native conformation or physicochemical properties. Here we show that backbone amidine substitution offers a minimal, site-specific modification that enhances metabolic stability. Using the pentapeptide Leu-enkephalin as a model, amidine replacement of metabolically labile amides attenuated or blocked proteolysis in a position-dependent manner, with one analog preserving and even enhancing G-protein signaling at the μ-opioid receptor while reducing β-arrestin2 recruitment. Amidines thus provide a modular strategy to rescue promising peptide leads limited by metabolic instability, with the potential of conferring protease resistance without the need for wholesale scaffold redesign.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"1777-1783"},"PeriodicalIF":3.9,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13367194/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148449584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of novel cofactorless self-cleaving RNAs with activity at low pH.","authors":"Nae Sakimoto, Emily Matsusaka, Natsuki Doi, Tell Biwata, Taku Ishigaki, Tomoka Akita, Elisa Tomita-Sudo, Shigenori Iwai, Junji Kawakami","doi":"10.1039/d6cb00054a","DOIUrl":"10.1039/d6cb00054a","url":null,"abstract":"<p><p>Several diseases abnormally lower cellular pH owing to metabolic pathway changes. Developing drugs based on genetic material that act only in target tissues may reduce side effects by exploiting the differences between diseased and normal tissue environments. Most naturally occurring ribozymes-ribonucleic acids with catalytic activity-are active at a neutral pH and inactive at lower pH. Ribozymes that cleave RNA only in acidic solutions require a general acid with a sufficiently low p<i>K</i> _a and a general base with a p<i>K</i> _a closer to the acidic region. As the rational design of such a ribozyme is difficult, we performed an <i>in vitro</i> assay for the selection of self-cleaving RNAs under acidic conditions. We attempted to develop a self-cleaving RNA that only acts in acidic solutions without requiring divalent metal cations, as the activity of natural ribozymes is affected by the presence or absence of these ions. To obtain RNA molecules with high activity under any conditions, <i>in vitro</i> selection was performed in the absence of divalent metal ions and cofactors. Using this method, we obtained a new functional RNA with self-cleavage activity only at an acidic pH. This RNA also exhibited high activity in the absence of divalent metal ions. This study derived a novel functional RNA. The obtained RNAs were shortened to a 53-nucleotide RNA with the original properties, and the sequence required for the catalytic activity was identified.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"1793-1803"},"PeriodicalIF":3.9,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13384015/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148608507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Outstanding Reviewers for <i>RSC Chemical Biology</i> in 2025.","authors":"","doi":"10.1039/d6cb90030e","DOIUrl":"https://doi.org/10.1039/d6cb90030e","url":null,"abstract":"<p><p>We would like to take this opportunity to thank all of <i>RSC Chemical Biology</i>'s reviewers for helping to preserve quality and integrity in chemical science literature. We would also like to highlight the Outstanding Reviewers for <i>RSC Chemical Biology</i> in 2025.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13397074/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Illuminating spatial dynamics of glutamine metabolism with a sensitive genetically encoded biosensor.","authors":"Jack M Scully, Michael J Sun, Siddharth Das, Nataly J Arias, Edmund D Kapelczak, Tiffany D Robinson, Katie G Vineall, Teagan S Dean, Tara TeSlaa, Ajit S Divakaruni, Danielle L Schmitt","doi":"10.1039/d6cb00164e","DOIUrl":"10.1039/d6cb00164e","url":null,"abstract":"<p><p>Glutamine is the most abundant amino acid in serum, used as a key nutrient by cells for protein synthesis, energy production, carbon and nitrogen metabolism, and cellular redox balance. The use of glutamine in the cell is highly compartmentalized, but the dynamics of glutamine metabolism across organelles and individual cells are not fully understood. To illuminate subcellular glutamine dynamics, we developed a green fluorescent protein-based intracellular glutamine optical reporter, iGlo. We find iGlo is sensitive and specific for glutamine and can be used to measure glutamine uptake, production, and consumption with high spatiotemporal resolution in multiple cell types. Furthermore, multiplexed imaging of iGlo with a lactate biosensor in single cells reveals the temporal crosstalk between glucose and glutamine metabolism to maintain energy homeostasis. Thus, iGlo enables the sensitive and precise study of compartmentalized glutamine dynamics and represents a new and enhanced tool for studying the spatiotemporal dynamics and regulation of metabolism.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"1839-1855"},"PeriodicalIF":3.9,"publicationDate":"2026-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13446454/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148686126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NovaID: photocatalytic proximity labeling with an engineered HyperNova.","authors":"Jianbei Zhu, Ziyuan Wang, Qishuo Zheng, Hao Sun, Shuo Han","doi":"10.1039/d6cb00091f","DOIUrl":"10.1039/d6cb00091f","url":null,"abstract":"<p><p>Photocatalytic proximity labeling has transformed the mapping of local molecular environments in living cells, but many existing platforms depend on flavin, heme, or metal cofactors, limiting their broader deployment. Here we repurpose HyperNova, a monomeric photosensitizer with an autocatalytically formed chromophore, as a genetically encoded photocatalyst for photocatalytic proximity labeling. Using biotin-aniline as the substrate, we show that HyperNova enables 560 nm light-activated proximity labeling across multiple subcellular compartments in living cells. We further engineer a blue-light-activated variant, HyperNova Green, and demonstrate that HyperNova and HyperNova Green can be selectively activated by 560 nm and 460 nm light, respectively, enabling dual-wavelength orthogonal labeling within the same sample and in distinct compartments of the same cell. In addition, fusion of HyperNova to Antares2 enables bioluminescence resonance energy transfer (BRET)-mediated activation, offering an external-illumination-free mode of proximity labeling. Together, these results establish NovaID as a compact and versatile proximity labeling platform with broad potential for spatiotemporally-resolved mapping of local subcellular environments.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"1716-1723"},"PeriodicalIF":3.9,"publicationDate":"2026-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13358894/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148438210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The KDM6 histone H3K27me3 demethylase inhibitor GSK-J4 induces metal and stress responses in multiple myeloma cells.","authors":"Adam P Cribbs, Edward S Hookway, Clarence Yapp, Ka-Hing Che, James E Dunford, Karina Gutheridge, Charlotte Palmer, Federica Lari, Graham Wells, Martin Philpott, Peter Cain, Deborah Brotherton, Eleanor Calcutt, Anvesha Saxena, Hal Drakesmith, Matthew T O Holland, Wolfgang Maret, Jude Fitzgibbons, Paul E Brennan, John C Christianson, Udo Oppermann","doi":"10.1039/d6cb00162a","DOIUrl":"10.1039/d6cb00162a","url":null,"abstract":"<p><p>Thioneins are cysteine-rich apoproteins that regulate divalent metal homeostasis by virtue of their metal-chelation properties resulting in the ligand-bound metallothionein state. Previous studies show transient upregulation of the metallothionein (MT) gene cluster as part of a complex transcriptional response to a class of histone H3K27me3 demethylase tool compounds targeting human Fe²⁺ dependent ketoglutarate oxygenases KDM6A (UTX) and KDM6B (JmjD3). The prototypic bioactive KDM6 inhibitor GSK-J4 induces apoptotic cell death in multiple myeloma cells and corresponding transcriptomic profiles are dominated by metal and integrated stress response (ISR) signatures, also observed in primary human myeloma cells. Here we investigate the hypothesis that metal-chelation by GSK-J4 provides the means for transport and intracellular release of Zn²⁺ leading to a metallothionein transcriptomic response signature. Live cell imaging of myeloma cells shows transient increases in intracellular free Zn²⁺ concentrations when exposed to GSK-J4, consistent with a model of inhibitor-mediated metal transport, further supported by direct metal-inhibitor complex formation as determined by MALDI-TOF mass spectrometry and ¹H NMR. Comparisons of GSK-J4 and ZnSO₄ treatments in the presence or absence of metal chelators show that both treatment conditions induce different transcription factor repertoires with an overlapping MTF1 transcriptional regulation responsible for metallothionein and metal ion transport regulation. The data provide a possible explanation for the observed metal response upon GSK-J4 inhibition however the relationship with the pro-apoptotic ISR mechanism in myeloma cells requires further investigation.</p>","PeriodicalId":40691,"journal":{"name":"RSC Chemical Biology","volume":" ","pages":"2014-2027"},"PeriodicalIF":3.9,"publicationDate":"2026-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13470865/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148762617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}