Journal of structural biology最新文献

{"title":"Determinants of site-selectivity in human ileal bile acid-binding protein by NMR dynamic analysis of a functionally-impaired mutant","authors":"Tamara Teski ,&nbsp;Gergő Horváth ,&nbsp;Orsolya Toke","doi":"10.1016/j.jsb.2025.108202","DOIUrl":"10.1016/j.jsb.2025.108202","url":null,"abstract":"<div><div>Human ileal bile acid-binding protein (hI-BABP), a member of the family of intracellular lipid-binding proteins, has a key role in the enterohepatic circulation of bile salts. The two internal binding sites of hI-BABP exhibit positive cooperativity accompanied by a site preference of glycocholate (GCA) and glycochenodeoxycholate (GCDA), the two most abundant bile salts in the human body. Previous study of Q51A hI-BABP in its <em>apo</em> state, a mutant with lost site-selectivity, suggests that disruption of the hydrogen-bonding network in the vicinity of the C/D-turn has long-range dynamic effects. To improve our understanding of the determinants of site-selectivity in hI-BABP, a comparative NMR chemical shift and spin relaxation analysis of homo- and heterotypic bile salt complexes of wild-type and Q51A hI-BABP was carried out. The wild-type GCDA-complex shows a striking similarity with the thermodynamically most stable hI-BABP:GCDA:GCA complex in terms of both structure and dynamic behaviour, suggesting that the bound GCDA at site 1 has a decisive role in conveying key stabilizing interactions in the physiologically most abundant heterotypic complex. Destabilization of hI-BABP-GCDA by the functionally impairing mutation Q51A is indicated by both the increase of ms-timescale motions in key segments of the protein as well as by increased ps-ns local fluctuations superimposed on slow motions. Our study suggests that binding interactions in hI-BABP might be modulated by altering the dynamic behaviour of specific segments in the protein with implications for targeting the intracellular trafficking of bile salts and bile salt-induced stimulation of nuclear receptors.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108202"},"PeriodicalIF":3.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873613","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":"2.0 Å cryo-EM structure of the 55 kDa nucleoplasmin domain of AtFKBP53","authors":"Nikhil Bharambe ,&nbsp;Ketul Saharan ,&nbsp;Dileep Vasudevan ,&nbsp;Sandip Basak","doi":"10.1016/j.jsb.2025.108203","DOIUrl":"10.1016/j.jsb.2025.108203","url":null,"abstract":"<div><div>The knowledge of three-dimensional structures of biological macromolecules is crucial for understanding the molecular mechanisms underlying disease pathology and for devising drugs targeting specific molecules. Single particle cryo-electron microscopy (Cryo-EM) has become indispensable for this purpose, particularly for large macromolecules and their complexes. However, its effectiveness has been limited in achieving near-atomic resolution for smaller macromolecules. This study presents the Cryo-EM structure of a 55 kDa pentameric AtFKBP53 nucleoplasmin domain at 2.0 Å nominal resolution. Our approach involves selecting the optimal grid for data collection and precise alignment of small particles to enhance the resolution of the final 3D reconstructed map. In this study, we systematically processed cryo-EM dataset of a small molecule to improve alignment, and this data processing strategy can be used as a guidance to process the cryo-EM data of other small molecules.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108203"},"PeriodicalIF":3.0,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859033","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":"Phylogenetic analysis and structural studies of heteromeric acetyl-CoA carboxylase from the oleaginous Amazonian microalgae Ankistrodesmus sp.: Insights into the BC and BCCP subunits","authors":"Andry Mercedes Mavila ,&nbsp;Jhon Antoni Vargas ,&nbsp;Eloy Condori ,&nbsp;Erick Giancarlo Suclupe Farro ,&nbsp;Adriano Alves Furtado ,&nbsp;Josué Manuel López ,&nbsp;Silvia Lucila Gonzalez ,&nbsp;Humberto D’Muniz Pereira ,&nbsp;Jorge Luis Marapara ,&nbsp;Roger Ruiz Paredes ,&nbsp;Marianela Cobos ,&nbsp;Juan C. Castro ,&nbsp;Richard Charles Garratt ,&nbsp;Diego Antonio Leonardo","doi":"10.1016/j.jsb.2025.108200","DOIUrl":"10.1016/j.jsb.2025.108200","url":null,"abstract":"<div><div>Acetyl-CoA carboxylase (ACC) is an essential enzyme in fatty acid biosynthesis that catalyzes the formation of malonyl-CoA from acetyl-CoA. While structural studies on ACC components have largely focused on prokaryotes and higher plants, the assembly and molecular adaptations of ACC in microalgae remain underexplored. This study aimed to fill this gap by providing the first structural and evolutionary characterization of both biotin carboxylase (BC) and biotin carboxyl carrier protein (BCCP) from a microalga (<em>Ankistrodesmus</em> sp.<em>)</em>. Phylogenetic analysis revealed distinct evolutionary trajectories for BC and BCCP, with BC forming a chlorophyte-specific clade closely related to other oleaginous species, while BCCP displayed two distinct isoforms within green algae, resulting from gene duplication. The crystallographic structure of BC was solved in its apo (1.75 Å) and ADP-Mg²⁺-bound (1.90 Å) states, revealing conserved conformational changes associated with cofactor binding. BCCP from <em>Ankistrodesmus</em> sp. displayed a unique QLGTF/H motif instead of the canonical AMKXM biotinylation motif, suggesting loss of biotinylation capacity. However, the presence of three additional lysines in the protruding thumb loop, with Lys95 as a candidate for biotin attachment, indicates potential compensatory adaptations. SEC-MALS and pull-down assays confirmed the formation of a stable 1:1 BC-BCCP complex, and circular dichroism showed increased thermal stability of the complex, supporting its structural stability. This study highlights unique structural adaptations in <em>Ankistrodesmus</em> sp. ACC, emphasizing the evolutionary plasticity of BC and BCCP. These insights provide a foundation for future investigations into ACC regulation in photosynthetic organisms and offer potential biotechnological applications for optimizing lipid production in microalgae.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108200"},"PeriodicalIF":3.0,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768447","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":"Mechanistic insights into cyclodextrins as substrates and inhibitors of GH57 family amylopullulanase from Aquifex aeolicus","authors":"Zhimin Zhu ,&nbsp;Minjun Li ,&nbsp;Qin Xu ,&nbsp;Liqing Huang ,&nbsp;Huan Zhou ,&nbsp;Weiwei Wang ,&nbsp;Qisheng Wang ,&nbsp;Feng Yu","doi":"10.1016/j.jsb.2025.108199","DOIUrl":"10.1016/j.jsb.2025.108199","url":null,"abstract":"<div><div>Maltooligosaccharides (MOs) have gained significant attention in the food and pharmaceutical industries owing to their valuable functional properties, including controlled sweetness, digestibility, and enhanced bioavailability. However, conventional MOs is production involves complex processing steps and significant production costs. A potential high-efficiency synthesis of specific MOs can be achieved through the ring-opening reaction of cyclodextrins (CDs) catalyzed by amylolytic enzymes. In this study, we analyze the catalytic conversion of α-, β-, and γ-CDs by a GH57 family amylopullulanase from <em>Aquifex aeolicus</em> (AaApu) using thin-layer chromatography (TLC). Our findings demonstrate that AaApu has a substrate specificity for γ-CD, while all three CDs exert competitive inhibition on pullulan hydrolysis. To elucidate the molecular mechanism of CDs as inhibitor and substrate of amylopullulanase, we determined high-resolution crystal structures of AaApu (wild-type and D352N) in complex with α-, β-, and γ-CD through co-crystallization. These findings establish a structure–function framework for understanding the bifunctional nature of CDs as both substrates and inhibitors in GH57 amylopullulanases.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108199"},"PeriodicalIF":3.0,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143692443","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":"Structural insights into the RNA binding inhibitors of the C-terminal domain of the SARS-CoV-2 nucleocapsid","authors":"Preeti Dhaka,&nbsp;Jai Krishna Mahto,&nbsp;Ankur Singh,&nbsp;Pravindra Kumar,&nbsp;Shailly Tomar","doi":"10.1016/j.jsb.2025.108197","DOIUrl":"10.1016/j.jsb.2025.108197","url":null,"abstract":"<div><div>The SARS-CoV-2 nucleocapsid (N) protein is an essential structural element of the virion, playing a crucial role in enclosing the viral genome into a ribonucleoprotein (RNP) assembly, as well as viral replication and transmission. The C-terminal domain of the N-protein (N-CTD) is essential for encapsidation, contributing to the stabilization of the RNP complex. In a previous study, three inhibitors (ceftriaxone, cefuroxime, and ampicillin) were screened for their potential to disrupt the RNA packaging process by targeting the N-protein. However, the binding efficacy, mechanism of RNA binding inhibition, and molecular insights of binding with N-CTD remain unclear. In this study, we evaluated the binding efficacy of these inhibitors using isothermal titration calorimetry (ITC), revealing the affinity of ceftriaxone (18 ± 1.3 μM), cefuroxime (55 ± 4.2 μM), and ampicillin (28 ± 1.2 μM) with the N-CTD. Further inhibition assay and fluorescence polarisation assay demonstrated RNA binding inhibition, with IC₅₀ ranging from ∼ 12 to 18 μM and K_D values between 24 μM to 32 μM for the inhibitors, respectively. Additionally, we also determined the inhibitor-bound complex crystal structures of N-CTD-Ceftriaxone (2.0 Å) and N-CTD-Ampicillin (2.2 Å), along with the structure of apo N-CTD (1.4 Å). These crystal structures revealed previously unobserved interaction sites involving residues K261, K266, R293, Q294, and W301 at the oligomerization interface and the predicted RNA-binding region of N-CTD. These findings provide valuable molecular insights into the inhibition of N-CTD, highlighting its potential as an underexplored but promising target for the development of novel antiviral agents against coronaviruses.</div></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"217 2","pages":"Article 108197"},"PeriodicalIF":3.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143669161","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":"Conformational landscape of the mycobacterial inosine 5′-monophosphate dehydrogenase octamerization interface","authors":"Ondřej Bulvas,&nbsp;Zdeněk Knejzlík,&nbsp;Anatolij Filimoněnko,&nbsp;Tomáš Kouba,&nbsp;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⁺ 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 ,&nbsp;Indrani Ghosh ,&nbsp;Samima Khatun ,&nbsp;Nilanjan Ghosh ,&nbsp;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}

{"title":"MRGPRX2 ligandome: Molecular simulations reveal three categories of ligand-receptor interactions","authors":"Philip Maier ,&nbsp;Moritz Macht ,&nbsp;Silvan Beck ,&nbsp;Pavel Kolkhir ,&nbsp;Magda Babina ,&nbsp;Andreas E. Kremer ,&nbsp;Dirk Zahn ,&nbsp;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}

{"title":"Allosteric inhibition of cytosolic NADP+-dependent isocitrate dehydrogenase by oxaloacetate","authors":"Dong Kyu Kim ,&nbsp;Ha Yeon Cho ,&nbsp;Hyo Je Cho ,&nbsp;Beom Sik Kang","doi":"10.1016/j.jsb.2025.108183","DOIUrl":"10.1016/j.jsb.2025.108183","url":null,"abstract":"<div><div>NADP⁺-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}