StructurePub Date : 2025-05-30DOI: 10.1016/j.str.2025.05.003
Chu-Hsin Tseng, Wen-Lin Hsieh, Wesley Tien Chiang, Nien-Jen Hu, Chia-Liang Lin
{"title":"Structural insights into the interaction of Hir2 and Hpc2 in the yeast Hir histone chaperone complex","authors":"Chu-Hsin Tseng, Wen-Lin Hsieh, Wesley Tien Chiang, Nien-Jen Hu, Chia-Liang Lin","doi":"10.1016/j.str.2025.05.003","DOIUrl":"https://doi.org/10.1016/j.str.2025.05.003","url":null,"abstract":"The HIRA complex, composed of HIRA, UBN1, and CABIN1 in humans, plays a central role in histone chaperone activity and chromatin regulation by depositing the H3.3 histone variant into nucleosomes. Proper subunit interactions are critical for complex stability and function. In this study, we examine the interaction between Hir2 and Hpc2, the yeast homologs of HIRA and UBN1, using biochemical and structural approaches. We show that the N-terminal to the Hpc2-related domain (NHRD) of Hpc2 binds to the WD40 domain of Hir2, consistent with the human HIRA-UBN1 interaction. The crystal structure of the Hir2_WD40-Hpc2_NHRD complex reveals a seven-bladed β-propeller fold in Hir2_WD40, with Hpc2_NHRD forming an antiparallel β sheet interface. Notably, a unique five-stranded blade in Hir2_WD40, stabilized by proline residue P228, is essential for Hpc2 binding. Mutational analysis confirms key interface residues, providing structural insights into the evolutionary conservation of the HIRA complex.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"37 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144177018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The MIT domain of STAMBP autoinhibits its deubiquitination activity","authors":"Ziyue Chen, Guanchao Wang, Yifan Zhang, Jianping Ding","doi":"10.1016/j.str.2025.05.001","DOIUrl":"https://doi.org/10.1016/j.str.2025.05.001","url":null,"abstract":"STAMBP, a member of the JAMM family of deubiquitinases, specifically targets K63-linked polyubiquitin chains and plays a vital role in regulating the endosomal sorting of activated cell surface receptors. In this study, we conducted comprehensive biochemical analyses of full-length STAMBP and several fragments and demonstrated that the MIT domain binds tightly to the catalytic domain (CD), resulting in autoinhibition of its activity. The crystal structure of the MIT-CD complex reveals that the MIT domain occupies a large portion of the distal ubiquitin-binding site of the CD domain, thereby obstructing substrate binding. Additionally, our biochemical data show that STAM1 binding to STAMBP facilitates substrate binding and enhances its activity, whereas binding of CHMP3 does not relieve autoinhibition or enhance activity. In summary, our findings reveal an autoinhibition mechanism of STAMBP via its MIT domain and provide further insights into the relationships between STAMBP, STAM, and CHMP in regulating STAMBP’s activity.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"50 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144154229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
StructurePub Date : 2025-05-26DOI: 10.1016/j.str.2025.04.022
Amanda D. Stange, Lorena Zuzic, Birgit Schiøtt, Nils A. Berglund
{"title":"Exploring insulin-receptor dynamics: Stability and binding mechanisms","authors":"Amanda D. Stange, Lorena Zuzic, Birgit Schiøtt, Nils A. Berglund","doi":"10.1016/j.str.2025.04.022","DOIUrl":"https://doi.org/10.1016/j.str.2025.04.022","url":null,"abstract":"Insulin binding to the insulin receptor (IR) induces large conformational changes leading to receptor activation. Although there exists a considerable number of IR structures in different conformational and insulin-saturation states, they cannot provide dynamic information or the resolved order of events leading to receptor activation. In this study, we employed molecular dynamics (MD) simulations to the experimentally solved structures of IR-insulin complexes occurring under physiological concentration conditions. We observed that insulin bound to the hybrid sites induced opening of site 1, and that site 1-bound insulin contributed to the extension of the α helix in the C terminus of the <em>α</em> chain (αCT) and increased inter-domain stabilization. Many models have previously been proposed for the activation of IR. Based on our observations, we propose a novel “ladder-climbing” mechanism of insulin-induced IR activation, where insulin gradually migrates from site 2 to site 1 while inducing a controlled conformational change in IR.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"45 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144137153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
StructurePub Date : 2025-05-23DOI: 10.1016/j.str.2025.04.020
Qingbo Liu, Ruth J. Parsons, Kevin Wiehe, Robert J. Edwards, Kevin O. Saunders, Peng Zhang, Huiyi Miao, Kedamawit Tilahun, Julia Jones, Yue Chen, Bhavna Hora, Wilton B. Williams, David Easterhoff, Xiao Huang, Katarzyna Janowska, Katayoun Mansouri, Barton F. Haynes, Priyamvada Acharya, Paolo Lusso
{"title":"Acquisition of quaternary trimer interaction as a key step in the lineage maturation of a broad and potent HIV-1 neutralizing antibody","authors":"Qingbo Liu, Ruth J. Parsons, Kevin Wiehe, Robert J. Edwards, Kevin O. Saunders, Peng Zhang, Huiyi Miao, Kedamawit Tilahun, Julia Jones, Yue Chen, Bhavna Hora, Wilton B. Williams, David Easterhoff, Xiao Huang, Katarzyna Janowska, Katayoun Mansouri, Barton F. Haynes, Priyamvada Acharya, Paolo Lusso","doi":"10.1016/j.str.2025.04.020","DOIUrl":"https://doi.org/10.1016/j.str.2025.04.020","url":null,"abstract":"Although most broadly neutralizing antibodies (bNAbs) specific for the CD4-binding site (CD4-BS) of HIV-1 interact with a single gp120 protomer, a few mimic the quaternary binding mode of CD4, making contact with a second protomer through elongated heavy chain framework 3 (FRH3) or complementarity-determining region 1 (CDRH1) loops. Here, we show that a CDRH3-dominated anti-CD4-BS bNAb, CH103, establishes quaternary interaction despite regular-length FRH3 and CDRH1. This quaternary interaction is critical for neutralization and is primarily mediated by two FRH3 acidic residues that were sequentially acquired and subjected to strong positive selection during CH103 maturation. Cryoelectron microscopy (cryo-EM) structures confirmed the role of the two FRH3 acidic residues in mediating quaternary contact and demonstrated that CH103 reaches the adjacent gp120 protomer by virtue of its unique angle of approach. Thus, the acquisition of quaternary interaction may constitute a key step in the lineage maturation of a broad and potent HIV-1 neutralizing antibody.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"24 8 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144122795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
StructurePub Date : 2025-05-23DOI: 10.1016/j.str.2025.04.021
Weida Zhang, Yuanyuan Zhang, Weidong Mao, Tao Huang, Xinrong Yu, Xiaohong Qin, Li-Zhi Mi
{"title":"Unprocessed BMP9 precursor is an intrinsic antagonist for its active growth factor","authors":"Weida Zhang, Yuanyuan Zhang, Weidong Mao, Tao Huang, Xinrong Yu, Xiaohong Qin, Li-Zhi Mi","doi":"10.1016/j.str.2025.04.021","DOIUrl":"https://doi.org/10.1016/j.str.2025.04.021","url":null,"abstract":"BMP9, a member of the TGFβ superfamily, plays a crucial role in angiogenesis, tissue development, and innate immunity. Dysregulation of BMP9 signaling is implicated in various diseases. Unlike latent TGFβs, BMP9 is produced as a precursor that is processed into an active pro-protein complex. However, the regulatory mechanisms governing the precursor’s activity and its biological functions have been largely unexplored. In this study, we demonstrate that the unprocessed BMP9 precursor acts as an intrinsic antagonist to its pro-protein in angiogenesis and osteogenesis. This inhibition occurs through competitive binding to the receptors ENG and ALK1. We also identify structural requirements for the precursor’s recognition by these receptors. Our findings reveal previously underappreciated functions of the BMP9 precursor and its regulatory mechanisms in growth factor signaling, with significant implications for developmental biology and clinical interventions.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"45 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144122873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
StructurePub Date : 2025-05-21DOI: 10.1016/j.str.2025.04.019
Jun-Ping Bai, Chenou Zhang, Iman Bahader, Nicola Strenzke, Vijay Renigunta, Dominik Oliver, Dhasakumar Navaratnam, Oliver Beckstein, Joseph Santos-Sacchi
{"title":"Chloride binding does not influence prestin motor speed at very high frequencies in the mouse outer hair cell","authors":"Jun-Ping Bai, Chenou Zhang, Iman Bahader, Nicola Strenzke, Vijay Renigunta, Dominik Oliver, Dhasakumar Navaratnam, Oliver Beckstein, Joseph Santos-Sacchi","doi":"10.1016/j.str.2025.04.019","DOIUrl":"https://doi.org/10.1016/j.str.2025.04.019","url":null,"abstract":"Prestin (SLC26A5) promotes mechanical feedback via outer hair cells (OHC) within the organ of Corti, governed by voltage-dependent kinetics of its charge movements; namely, nonlinear-capacitance (NLC). We study NLC frequency response in mouse OHC membrane patches. The characteristic frequency cut-off (F<sub>is</sub>) is 27 kHz. Single point mutations within prestin’s chloride binding pocket (S396E and S398E) lack usual anion influence. In agreement, we show absence of anion binding in these mutants through molecular dynamics (MD) simulations. NLC F<sub>is</sub> in S396E knock-in mice is unaltered, indicating that high frequency activity is not governed by chloride but likely by viscoelastic loads. Also, the allosteric action of chloride does not underlie piezoelectric-like behavior in prestin, since tension sensitivity of S396E NLC is comparable to WT. Because structures of all studied species appear indistinguishable, with analogous chloride binding pockets, prestin performance likely evolved by modifying, not its protein-anion interaction, but instead mechanical loads on the protein.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"94 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144103984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
StructurePub Date : 2025-05-21DOI: 10.1016/j.str.2025.04.018
Daniel Santos, Lorenzo Foglia, Philip D. Kiser, Alvin Yu
{"title":"The molecular mechanisms of visual chromophore release from cellular retinaldehyde-binding protein","authors":"Daniel Santos, Lorenzo Foglia, Philip D. Kiser, Alvin Yu","doi":"10.1016/j.str.2025.04.018","DOIUrl":"https://doi.org/10.1016/j.str.2025.04.018","url":null,"abstract":"Cellular retinaldehyde-binding protein (CRALBP) is an 11-<em>cis</em>-retinoid binding protein operating within the visual cycle. CRALBP serves as the terminal acceptor of 11-<em>cis</em>-retinaldehyde (11cRAL) produced within the retinal pigment epithelium (RPE) and mediates 11cRAL transport to the RPE apical microvilli. Crystallographic structures of CRALBP revealed that the 11cRAL-binding pocket is sealed off from bulk solvent, indicating a necessity for conformational changes to allow ligand egress. Here, we performed long timescale all-atom molecular dynamics simulations of CRALBP to elucidate the mechanisms of ligand release. CRALBP exhibits slower diffusive behavior in the presence of membranes containing negatively charged phospholipids, which bind to an exposed cationic pocket in CRALBP. Umbrella sampling calculations revealed thermodynamically likely pathways for 11cRAL egress. Our data suggest that the CRALBP-acidic phospholipid interaction facilitates 11cRAL release through allosteric, conformational changes that perturb the binding site, lowering ligand affinity. These findings offer insights into the molecular pathology of CRALBP-associated retinopathy.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"9 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144103989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
StructurePub Date : 2025-05-16DOI: 10.1016/j.str.2025.04.017
Minjae Kim, Jinwoo Kim, Gyu Sung Lee, Paul Dominic B. Olinares, Yougant Airan, Jasmine L. Chow, Jongseok Park, Yujin Jeong, Jiho Park, Brian T. Chait, Seth B. Herzon, Chung Sub Kim, Jin Young Kang
{"title":"Structural study on human microbiome-derived polyketide synthases that assemble genotoxic colibactin","authors":"Minjae Kim, Jinwoo Kim, Gyu Sung Lee, Paul Dominic B. Olinares, Yougant Airan, Jasmine L. Chow, Jongseok Park, Yujin Jeong, Jiho Park, Brian T. Chait, Seth B. Herzon, Chung Sub Kim, Jin Young Kang","doi":"10.1016/j.str.2025.04.017","DOIUrl":"https://doi.org/10.1016/j.str.2025.04.017","url":null,"abstract":"Colibactin, a human microbiome-derived genotoxin, promotes colorectal cancer by damaging the host gut epithelial genomes. While colibactin is synthesized via a hybrid non-ribosomal peptide synthetase (NRPS)-polyketide synthase (PKS) pathway, known as <em>pks</em> or <em>clb</em>, the structural details of its biosynthetic enzymes remain limited, hindering our understanding of its biosynthesis and clinical application. In this study, we report the cryo-EM structures of two colibactin-producing PKS enzymes, ClbC and ClbI, captured in different reaction states using a substrate-mimic crosslinker. Our structural analysis revealed the binding sites of carrier protein (CP) domains of the ClbC and ClbI on their ketosynthase (KS) domains. Further, we identified a novel NRPS-PKS docking interaction between ClbI and its upstream enzyme, ClbH, mediated by the C-terminal peptide ClbH and the dimeric interface of ClbI, establishing a 1:2 stoichiometry. These findings advance our understanding of colibactin assembly line and provide broader insights into NRPS-PKS natural product biosynthesis mechanisms.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"35 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
StructurePub Date : 2025-05-14DOI: 10.1016/j.str.2025.04.016
Mohammad M. Sajadi, Abdolrahim Abbasi, Zahra Rikhtegaran Tehrani, Christine Siska, Rutilio Clark, Woo Chi, Michael S. Seaman, Dieter Mielke, Kshitij Wagh, Qingbo Liu, Taylor Jumpa, Randal R. Ketchem, Dung N. Nguyen, William D. Tolbert, Brian G. Pierce, Ben Atkinson, Derrick Deming, Megan Sprague, Andrew Asakawa, David Ferrer, Anthony DeVico
{"title":"A comprehensive engineering strategy improves potency and manufacturability of a near pan-neutralizing antibody against HIV","authors":"Mohammad M. Sajadi, Abdolrahim Abbasi, Zahra Rikhtegaran Tehrani, Christine Siska, Rutilio Clark, Woo Chi, Michael S. Seaman, Dieter Mielke, Kshitij Wagh, Qingbo Liu, Taylor Jumpa, Randal R. Ketchem, Dung N. Nguyen, William D. Tolbert, Brian G. Pierce, Ben Atkinson, Derrick Deming, Megan Sprague, Andrew Asakawa, David Ferrer, Anthony DeVico","doi":"10.1016/j.str.2025.04.016","DOIUrl":"https://doi.org/10.1016/j.str.2025.04.016","url":null,"abstract":"Anti-HIV envelope broadly neutralizing antibodies (bnAbs) are alternatives to conventional antiretrovirals with the potential to prevent and treat infection, reduce latent reservoirs, and/or mediate a functional cure. Clinical trials with “first-generation” bnAbs used alone or in combination show promising antiviral effects but also highlight that additional engineering of “enhanced” antibodies will be required for optimal clinical utility, while preserving or enhancing Current Good Manufacturing Practices (cGMP) manufacturing capability. Here, we report the engineering of an anti-CD4-binding site (CD4bs) bnAb, N49P9.3. Through a series of rational modifications, we produced a variant, N49P9.6-FR-LS, that demonstrates enhanced potency, superior antiviral activity in combination with other bnAbs, low polyreactivity, and longer circulating half-life. Additional engineering for manufacturing produced a final variant, eN49P9, with properties conducive to cGMP production. Overall, these efforts demonstrate the feasibility of developing enhanced anti-CD4bs bnAbs with greatly improved antiviral properties as well as potential translational value.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"2 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143946274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
StructurePub Date : 2025-05-14DOI: 10.1016/j.str.2025.04.009
Jake C. Lachowicz, Steven Grudman, Jeffrey B. Bonanno, Andras Fiser, Tyler L. Grove
{"title":"Structural insights from active site variants and β-8 loop interactions in viperin-like enzymes","authors":"Jake C. Lachowicz, Steven Grudman, Jeffrey B. Bonanno, Andras Fiser, Tyler L. Grove","doi":"10.1016/j.str.2025.04.009","DOIUrl":"https://doi.org/10.1016/j.str.2025.04.009","url":null,"abstract":"Viperin and viperin-like enzymes (VLEs) are members of the radical SAM superfamily that perform radical-mediated dehydrations on nucleoside triphosphates to yield 3′-deoxy-3′,4′-didehydronucleoside triphosphates (ddhNTPs). Interestingly, viperin and VLEs demonstrate species-dependent substrate selectivity. Some fungal species have a second VLE and, while most viperin and VLEs contain an NΦHX<sub>4</sub>CX<sub>3</sub>CX<sub>2</sub>CF motif, these secondary VLEs are catalytically hindered by a histidine to phenylalanine substitution, an NΦFX<sub>4</sub>CX<sub>3</sub>CX<sub>2</sub>CF motif (NΦF). Herein, we utilize a combination of bioinformatics, enzymology, and X-ray crystallography to demonstrate that NΦF VLEs likely utilize CTP as a substrate. Based on these observations, we demonstrate that the β-8 loop in TvVip1 can be engineered with the β-8 loop from a CTP-selective viperin (<em>Mus musculus</em>) to “swap” substrate selectivity from UTP to CTP. These results provide insight into the determinants of substrate selectivity exhibited by VLEs and introduce a potential route for engineering viperin and VLEs to form alternative ddhNTPs.","PeriodicalId":22168,"journal":{"name":"Structure","volume":"33 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143946283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}