Ondřej Bulvas, Zdeněk Knejzlík, Anatolij Filimoněnko, Tomáš Kouba, Iva Pichová
{"title":"Conformational landscape of the mycobacterial inosine 5′-monophosphate dehydrogenase octamerization interface","authors":"Ondřej Bulvas, Zdeněk Knejzlík, Anatolij Filimoněnko, Tomáš Kouba, Iva Pichová","doi":"10.1016/j.jsb.2025.108198","DOIUrl":"10.1016/j.jsb.2025.108198","url":null,"abstract":"<div><div>Inosine 5′-monophosphate dehydrogenase (IMPDH), a key enzyme in bacterial purine metabolism, plays an essential role in the biosynthesis of guanine nucleotides and shows promise as a target for antimicrobial drug development. Despite its significance, the conformational dynamics and substrate-induced structural changes in bacterial IMPDH remain poorly understood, particularly with respect to its octameric assembly. Using cryo-EM, we present full-length structures of IMPDH from <em>Mycobacterium smegmatis</em> (<em>Msm</em>IMPDH) captured in a reaction intermediate state, revealing conformational changes upon substrate binding. The structures feature resolved flexible loops that coordinate the binding of the substrate, the cofactor, and the K<sup>+</sup> ion. Our structural analysis identifies a novel octamerization interface unique to <em>Msm</em>IMPDH. Additionally, a previously unobserved barrel-like density suggests potential self-interactions within the C-terminal regions, hinting at a regulatory mechanism tied to assembly and function of the enzyme. These data provide insights into substrate-induced conformational dynamics and novel interaction interfaces in <em>Msm</em>IMPDH, potentially informing the development of IMPDH-targeted drugs.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108198"},"PeriodicalIF":3.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dengue virus-host interactions: Structural and mechanistic insights for future therapeutic strategies","authors":"Moumita Khanra , Indrani Ghosh , Samima Khatun , Nilanjan Ghosh , Shovanlal Gayen","doi":"10.1016/j.jsb.2025.108196","DOIUrl":"10.1016/j.jsb.2025.108196","url":null,"abstract":"<div><div>Dengue pathogen, transmitted by mosquitoes, poses a growing threat as it is capable of inflicting severe illness in humans. Around 40% of the global population is currently affected by the virus, resulting in thousands of fatalities each year. The genetic blueprint of the virus comprises 10 proteins. Three proteins serve as structural components: the capsid (C), the precursor of the membrane protein (PrM/M), and the envelope protein (E). The other proteins serve as non-structural (NS) proteins, consisting of NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5. The virus relies on these NS proteins to expropriate host proteins for its replication. During their intracellular replication, these viruses engage with numerous host components and exploit the cellular machinery for tasks such as entry into various organs, propagation, and transmission. This review explores mainly the relationship between dengue viral protein and host proteins elucidating the development of viral-host interactions. These relationships between the virus and the host give important information on the processes behind viral replication and the etiology of disease, which in turn facilitates the creation of more potent treatment strategies.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108196"},"PeriodicalIF":3.0,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143639637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"NMR and semi-synthesis in synergy to study protein regulation","authors":"Thibault Viennet","doi":"10.1016/j.jsb.2025.108192","DOIUrl":"10.1016/j.jsb.2025.108192","url":null,"abstract":"<div><div>Structural biology as a field has advanced immensely in the last few years, but the mechanistic roles of protein disordered regions and their associated post-translational modifications on the molecular level are still poorly understood. Nuclear magnetic resonance offers the possibility to investigate these regions with atomic resolution and understand the effect of protein modification, and thus protein regulation. However, obtaining suitable and well-defined samples is not straightforward. Here, I review some approaches to protein semi-synthesis for nuclear magnetic resonance purposes, and their applications. I hope to demonstrate that these chemical and structural biology techniques create a powerful synergy that enables structural studies of protein regulation.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108192"},"PeriodicalIF":3.0,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143634149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Philip Maier , Moritz Macht , Silvan Beck , Pavel Kolkhir , Magda Babina , Andreas E. Kremer , Dirk Zahn , Katharina Wolf
{"title":"MRGPRX2 ligandome: Molecular simulations reveal three categories of ligand-receptor interactions","authors":"Philip Maier , Moritz Macht , Silvan Beck , Pavel Kolkhir , Magda Babina , Andreas E. Kremer , Dirk Zahn , Katharina Wolf","doi":"10.1016/j.jsb.2025.108193","DOIUrl":"10.1016/j.jsb.2025.108193","url":null,"abstract":"<div><h3>Introduction</h3><div>Mas-related G protein-coupled receptor (MRGPR) X2 is a mast cell receptor known to be activated by a wide range of ligands of various size, charge and origin. Our aim is to gain a deeper understanding of the binding processes of the different MRGPRX2 ligands and the ligand-receptor interactions in order to identify crucial structural elements for receptor activation.</div></div><div><h3>Materials and methods</h3><div>We used the three-dimensional structure of MRGPRX2 described in <em>Nature</em> in 2021 by Cao et al. and Yang et al. to computationally model the interaction between MRGPRX2 and small molecule ligands under simulated physiological conditions.</div></div><div><h3>Results</h3><div>Docking and post-docking samplings of the MRGPRX2 ligandome within the GPCR binding pocket led to the identification of key structural features for protein–ligand interactions. On the ligand side, we obtained an overlay of different molecular patterns or chemical groups by comparing different ligands plotted on the receptor. These key features include at least one protonated amine moiety of MRGPRX2 ligands contributing to one salt-bridge and one π-cation interaction, as well as an extended non-polar domain of the ligand surface that offer hydrophobic segregation and/or π-stacking interactions. In the receptor, we identified amino acids (GLU164, ASP184, PHE101, PHE170, TRP243, PHE244 and PHE257) that specifically interact via hydrogen bonding, salt-bridges, π-cation interactions and π-π stacking with the ligands to direct binding and ultimately receptor activation.</div></div><div><h3>Discussion</h3><div>Our insights into ligand-receptor interaction obtained by molecular modeling can help to predict mast cell activation via MRGPRX2 including adverse reactions, and facilitate the development of MRGPRX2 antagonists for the treatment of mast cell-mediated diseases.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108193"},"PeriodicalIF":3.0,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143630507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dong Kyu Kim , Ha Yeon Cho , Hyo Je Cho , Beom Sik Kang
{"title":"Allosteric inhibition of cytosolic NADP+-dependent isocitrate dehydrogenase by oxaloacetate","authors":"Dong Kyu Kim , Ha Yeon Cho , Hyo Je Cho , Beom Sik Kang","doi":"10.1016/j.jsb.2025.108183","DOIUrl":"10.1016/j.jsb.2025.108183","url":null,"abstract":"<div><div>NADP<sup>+</sup>-dependent cytosolic isocitrate dehydrogenase (IDH1) plays a crucial role in providing reducing energy in response to oxidative stress through the oxidative decarboxylation of isocitrate. NADPH generated by IDH1 serves as an essential cofactor for fatty acid synthesis. The regulation of IDH1 activity is vital for the biological functions of NADPH within cells, and mutations in IDH1 have been implicated in various cancers. In an effort to identify small regulatory molecules for IDH1, we determined the crystal structures of mouse IDH1 complexed with isocitrate and with oxaloacetate. Each IDH1 comprises large and small domains that form an active site, along with a clasp domain that connects two IDH1 molecules for dimerization. Isocitrate was located at the active site in the presence of a magnesium ion, while oxaloacetate was found at a novel site formed by the two clasp domains, in addition to the active site. The activity of IDH1 was diminished in the presence of oxaloacetate and could not be restored by the addition of isocitrate, indicating the presence of allosteric regulation. The activity of the IDH1 H170A mutant, which is unable to bind oxaloacetate in the clasp domain, was unaffected by oxaloacetate. This allosteric regulatory site may serve as a potential target for novel IDH1 inhibitors.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108183"},"PeriodicalIF":3.0,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143597205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Improving CryoEM maps of symmetry-mismatched macromolecular assemblies: A case study on the flagellar motor","authors":"Prashant K. Singh , T.M. Iverson","doi":"10.1016/j.jsb.2025.108184","DOIUrl":"10.1016/j.jsb.2025.108184","url":null,"abstract":"<div><div>Advances in cryo-electron microscopy instrumentation and sample preparation have significantly improved the ability to collect quality data for biomolecular structures. However, achieving resolutions consistent with data quality remains challenging in structures with symmetry mismatches. As a case study, the bacterial flagellar motor is a large complex essential for bacterial chemotaxis and virulence. This motor contains a smaller membrane-supramembrane ring (MS-ring) and a larger cytoplasmic ring (C-ring). These two features have a 33:34 symmetry mismatch when expressed in <em>E. coli</em>. Because close symmetry mismatches are the most difficult to deconvolute, this makes the flagellar motor an excellent model system to evaluate refinement strategies for symmetry mismatch. We compared the performance of masked refinement, local refinement, and particle subtracted refinement on the same data. We found that particle subtraction prior to refinement was critical for approaching the smaller MS-ring. Additional processing resulted in final resolutions of 3.1 Å for the MS-ring and 3.0 Å for the C-ring, which improves the resolution of the MS-ring by 0.3 Å and the resolution of the C-ring by 1.0 Å as compared to past work. Although particle subtraction is fairly well-established, it is rarely applied to problems of symmetry mismatch, making this case study a valuable demonstration of its utility in this context.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108184"},"PeriodicalIF":3.0,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143585985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Niko Faul , Shih-Ya Chen , Christian Lamberz , Mark Bruckner , Christian Dienemann , Thomas P. Burg
{"title":"Cryo-iCLEM: Cryo correlative light and electron microscopy with immersion objectives","authors":"Niko Faul , Shih-Ya Chen , Christian Lamberz , Mark Bruckner , Christian Dienemann , Thomas P. Burg","doi":"10.1016/j.jsb.2025.108179","DOIUrl":"10.1016/j.jsb.2025.108179","url":null,"abstract":"<div><div>Correlative light and electron microscopy (CLEM) is a powerful tool for investigating cellular structure and function at the molecular level. However, while electron microscopy is often performed to great advantage at cryogenic temperatures, this is not always the case for light microscopy. One key challenge is the lack of cryo-compatible immersion objectives. In recent years, multiple cryoimmersion light microscopy (cryo-iLM) approaches have been described, but these techniques have never been used in correlative approaches. Here we present a novel workflow for correlative cryoimmersion light microscopy and electron cryomicroscopy (cryo-iCLEM). Cryo-electron tomography conducted before and after cryo-iLM reveals that cryo-iCLEM maintains ultra-thin, electron-transparent samples mechanically intact and does not degrade the ultrastructural preservation achieved through plunge-freezing. For cryo-iLM, the sample is first embedded in a viscous immersion medium at cryogenic temperatures and examined with a custom cryo-immersion objective. After cryo-iLM, the immersion medium is dissolved in liquid ethane, allowing for subsequent cryo-EM imaging. We further show that cryo-iCLEM can be used on FIB-lamellae, demonstrating that mechanically sensitive samples remain undamaged. Embedding the sample in the immersion fluid reduces contamination and thus allows data acquisition over many hours. Samples can therefore be examined in detail with the advantage of low bleaching rates of fluorophores at cryogenic temperatures. In the future, we hope that our approach can help improve the performance of many advanced light microscopy techniques when they are applied in the context of cryo-CLEM.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 1","pages":"Article 108179"},"PeriodicalIF":3.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143458330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Isabella Silva Barreto , Marianne Liebi , Sophie Le Cann , Saima Ahmed , Leonard C. Nielsen , Tilman A. Grünewald , Hector Dejea , Viviane Lutz-Bueno , Niamh C. Nowlan , Hanna Isaksson
{"title":"Lack of embryonic skeletal muscle in mice leads to abnormal mineral deposition and growth","authors":"Isabella Silva Barreto , Marianne Liebi , Sophie Le Cann , Saima Ahmed , Leonard C. Nielsen , Tilman A. Grünewald , Hector Dejea , Viviane Lutz-Bueno , Niamh C. Nowlan , Hanna Isaksson","doi":"10.1016/j.jsb.2025.108178","DOIUrl":"10.1016/j.jsb.2025.108178","url":null,"abstract":"<div><div>Developing bones can be severely impaired by a range of disorders where muscular loading is abnormal. Recent work has indicated that the effects of absent skeletal muscle on bones are more severe early in development, with rudiment length and mineralization lengths being almost normal in muscle-less limbs just prior to birth. However, the impact of abnormal mechanical loading on the nanoscale structure and composition during prenatal mineralization remains unknown. In this exploratory study, we characterized the mineralization process of humeri from muscle-less limb embryonic mice using a multiscale approach by combining X-ray scattering and fluorescence with infrared and light microscopy to identify potential key aspects of interest for future in-depth investigations. Muscle-less humeri were characterized by initially less mineralized tissue to later catch up with controls, and exhibited continuous growth of mineral particles, which ultimately led to seemingly larger mineral particles than their controls at the end of development. Muscle-less limbs exhibited an abnormal pattern of mineralization, reflected by a more widespread distribution of zinc and homogenous distribution of hydroxyapatite compared to controls, which instead showed trabecular-like structures and zinc localized only to regions of ongoing mineralization. The decrease in collagen content in the hypertrophic zone due to resorption of the cartilage collagen matrix was less distinct in muscle-less limbs compared to controls. Surprisingly, the nanoscale orientation of the mineral particles was unaffected by the lack of skeletal muscle. The identified accelerated progression of ossification in muscle-less limbs at later prenatal stages provides a possible anatomical mechanism underlying their recovery in skeletal development.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 1","pages":"Article 108178"},"PeriodicalIF":3.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143433421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kristina Vogel , Johanna Moeller , Nina G. Bozhanova , Markus Voehler , Anja Penk , Jens Meiler , Clara T. Schoeder
{"title":"Computational Engineering of siderocalin to modulate its binding affinity to the antihypertension drug candesartan","authors":"Kristina Vogel , Johanna Moeller , Nina G. Bozhanova , Markus Voehler , Anja Penk , Jens Meiler , Clara T. Schoeder","doi":"10.1016/j.jsb.2025.108180","DOIUrl":"10.1016/j.jsb.2025.108180","url":null,"abstract":"<div><div>Lipocalin family proteins have been shown to bind a vast array of small molecules and have subsequently been adapted to selectively bind specific ligands. In this study, candesartan, an antihypertension drug, was identified to bind mouse and human siderocalin in biomolecular NMR experiments, allowing for structural insights into the candesartan-siderocalin interaction. The ligand binding site was determined through an integrative structural biology approach using <em>in silico</em> ligand docking guided by NMR experiments. Building on this structurally informed binding model, we used rational protein design to modulate the binding pocket for increased or decreased ligand binding affinity. The predicted mutations were evaluated <em>in vitro</em> using isothermal titration calorimetry. This resulted in a mutant with a 50-fold increase in binding affinity in addition to a second mutant with a five-fold decrease in binding affinity. Thus, siderocalins have potential as a scaffold for creation of various ligand binding-based tools, including drug scavengers.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 1","pages":"Article 108180"},"PeriodicalIF":3.0,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143468251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effects of Gα C-terminal deletion on the intrinsic GDP release/GTPase activity and conformational dynamics","authors":"Junyoung Kim, Ka Young Chung","doi":"10.1016/j.jsb.2025.108182","DOIUrl":"10.1016/j.jsb.2025.108182","url":null,"abstract":"<div><div>Heterotrimeric G proteins (G proteins) serve as key signaling mediators downstream of G protein-coupled receptors (GPCRs). Comprised of Gα, Gβ, and Gγ subunits, the activation state of Gα, determined by GDP or GTP binding, governs G protein activity. While high-resolution structures of GPCR-G protein complexes have identified the Gα C-terminal 5 residues (<em>i.e.,</em> wavy hook) as critical for GPCR binding and coupling selectivity, its influence on Gα’s intrinsic biochemical properties remains unclear. Here, we investigated the role of wavy hook truncation in the intrinsic GDP/GTP turnover rate, GTPase activity, and conformational dynamics of Gαs and Gαi1 using BODIPY-labeled nucleotides and hydrogen/deuterium exchange mass spectrometry (HDX-MS). Truncation of the wavy hook significantly altered the GDP/GTP turnover rate, GTPase activity, and conformational flexibility of Gαs, particularly at the p-loop through α1 region, but had minimal impact on Gαi1. These findings reveal subtype-specific effects of the wavy hook on G protein stability and conformational dynamics, highlighting the importance of structural elements in regulating G protein function and their implications for GPCR signaling studies.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108182"},"PeriodicalIF":3.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143537316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}