Journal of structural biology最新文献

{"title":"Crystal structure of the Mycobacterium tuberculosis VirS regulator reveals its interaction with the lead compound SMARt751","authors":"Camille Grosse ,&nbsp;Maud Sigoillot ,&nbsp;Véronique Megalizzi ,&nbsp;Abdalkarim Tanina ,&nbsp;Nicolas Willand ,&nbsp;Alain R. Baulard ,&nbsp;René Wintjens","doi":"10.1016/j.jsb.2024.108090","DOIUrl":"10.1016/j.jsb.2024.108090","url":null,"abstract":"<div><p>Ethionamide (ETO) is a prodrug that is primarily used as a second-line agent in the treatment of tuberculosis. Among the bacterial ETO activators, the monooxygenase MymA has been recently identified, and its expression is regulated by the mycobacterial regulator VirS. The discovery of VirS ligands that can enhance <em>mymA</em> expression and thereby increase the antimycobacterial efficacy of ETO, has led to the development of a novel therapeutic strategy against tuberculosis. This strategy involves the selection of preclinical candidates, including SMARt751. We report the first crystal structure of the AraC-like regulator VirS, in complex with SMARt751, refined at 1.69 Å resolution. Crystals were obtained via an <em>in situ</em> proteolysis method in the requisite presence of SMARt751. The elucidated structure corresponds to the ligand-binding domain of VirS, adopting an α/β fold with structural similarities to H-NOX domains. Within the VirS structure, SMARt751 is situated in a completely enclosed hydrophobic cavity, where it forms hydrogen bonds with Asn11 and Asn149 as well as van der Waals contacts with various hydrophobic amino acids. Comprehensive structural comparisons within the AraC family of transcriptional regulators are conducted and analyzed to figure out the effects of the SMARt751 binding on the regulatory activity of VirS.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108090"},"PeriodicalIF":3.0,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140318461","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":"Unveiling success determinants for AMB-assisted phase expansion of fusion proteins in ARP/wARP","authors":"María C. Cardona-Echavarría ,&nbsp;Carmen Santillán ,&nbsp;Ricardo Miranda-Blancas ,&nbsp;Vivian Stojanoff ,&nbsp;Enrique Rudiño-Piñera","doi":"10.1016/j.jsb.2024.108089","DOIUrl":"10.1016/j.jsb.2024.108089","url":null,"abstract":"<div><p>Fusion proteins (FPs) are frequently utilized as a biotechnological tool in the determination of macromolecular structures using X-ray methods. Here, we explore the use of different protein tags in various FP, to obtain initial phases by using them in a partial molecular replacement (MR) and constructing the remaining FP structure with ARP/wARP. Usually, the tag is removed prior to crystallization, however leaving the tag on may facilitate crystal formation, and structural determination by expanding phases from known to unknown segments of the complex. In this study, the Protein Data Bank was mined for an up-to-date list of FPs with the most used protein tags, Maltose Binding Protein (MBP), Green Fluorescent Protein (GFP), Thioredoxin (TRX), Glutathione transferase (GST) and the Small Ubiquitin-like Modifier Protein (SUMO). Partial MR using the protein tag, followed by automatic model building, was tested on a subset of 116 FP. The efficiency of this method was analyzed and factors that influence the coordinate construction of a substantial portions of the fused protein were identified. Using MBP, GFP, and SUMO as phase generators it was possible to build at least 75 % of the protein of interest in 36 of the 116 cases tested. Our results reveal that tag selection has a significant impact; tags with greater structural stability, such as GFP, increase the success rate. Further statistical analysis identifies that resolution, Wilson B factor, solvent percentage, completeness, multiplicity, protein tag percentage in the FP (considering amino acids), and the linker length play pivotal roles using our approach. In cases where a structural homologous is absent, this method merits inclusion in the toolkit of protein crystallographers.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108089"},"PeriodicalIF":3.0,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140306058","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 and kinetic analysis of the monofunctional Staphylococcus aureus PBP1","authors":"Christopher G. Bon ,&nbsp;Jason C. Grigg ,&nbsp;Jaeyong Lee ,&nbsp;Craig S. Robb ,&nbsp;Nathanael A. Caveney ,&nbsp;Lindsay D. Eltis ,&nbsp;Natalie C.J. Strynadka","doi":"10.1016/j.jsb.2024.108086","DOIUrl":"10.1016/j.jsb.2024.108086","url":null,"abstract":"<div><p><em>Staphylococcus aureus</em>, an ESKAPE pathogen, is a major clinical concern due to its pathogenicity and manifold antimicrobial resistance mechanisms. The commonly used β-lactam antibiotics target bacterial penicillin-binding proteins (PBPs) and inhibit crosslinking of peptidoglycan strands that comprise the bacterial cell wall mesh, initiating a cascade of effects leading to bacterial cell death. <em>S. aureus</em> PBP1 is involved in synthesis of the bacterial cell wall during division and its presence is essential for survival of both antibiotic susceptible and resistant <em>S. aureus</em> strains. Here, we present X-ray crystallographic data for <em>S. aureus</em> PBP1 in its apo form as well as acyl-enzyme structures with distinct classes of β-lactam antibiotics representing the penicillins, carbapenems, and cephalosporins, respectively: oxacillin, ertapenem and cephalexin. Our structural data suggest that the PBP1 active site is readily accessible for substrate, with little conformational change in key structural elements required for its covalent acylation of β-lactam inhibitors. Stopped-flow kinetic analysis and gel-based competition assays support the structural observations, with even the weakest performing β-lactams still having comparatively high acylation rates and affinities for PBP1. Our structural and kinetic analysis sheds insight into the ligand–PBP interactions that drive antibiotic efficacy against these historically useful antimicrobial targets and expands on current knowledge for future drug design and treatment of <em>S. aureus</em> infections.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108086"},"PeriodicalIF":3.0,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1047847724000261/pdfft?md5=90b179f904d39532e74640b54f53d324&pid=1-s2.0-S1047847724000261-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140288409","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":"Melanin granules morphology and distribution in human black hair investigated by focused ion beam scanning electron microscopy: Differences between Asian and Caucasian hair","authors":"Toru Kojima ,&nbsp;Hiromi Yamada ,&nbsp;Sakiko Enomoto ,&nbsp;Tomoyo Nakao ,&nbsp;Shigeo Arai","doi":"10.1016/j.jsb.2024.108088","DOIUrl":"10.1016/j.jsb.2024.108088","url":null,"abstract":"<div><p>Melanin granules (melanosomes) in Asian and Caucasian black hairs were investigated by focused ion beam scanning electron microscopy (FIB-SEM). This technique facilitates a direct evaluation of the three-dimensional distribution and morphology of melanin granules without requiring their isolation from hair. Three-dimensional reconstructed images of melanin granule distribution in hair samples were obtained using serial SEM images observed by FIB-SEM. Melanin granules in black hair tended to be three-dimensionally dense in the outer periphery of the cortex. The morphometric parameters of melanin granules were calculated using the reconstructed three-dimensional images. The results confirmed that melanin granules in Caucasian black hair were much smaller those in Asian black hair. Moreover, it was indicated that the relative frequency distribution of the volume of melanin granules was significantly different between Asians and Caucasians.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108088"},"PeriodicalIF":3.0,"publicationDate":"2024-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140293791","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":"Molecular insights into the binding interactions and energetics of the omicron spike variant with hACE2 and a neutralizing antibody","authors":"Vipul Kumar ,&nbsp;Seyad Shefrin,&nbsp;Durai Sundar","doi":"10.1016/j.jsb.2024.108087","DOIUrl":"10.1016/j.jsb.2024.108087","url":null,"abstract":"<div><p>The global spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) since 2019 has led to a continuous evolution of viral variants, with the latest concern being the Omicron (B.1.1.529) variant. In this study, classical molecular dynamics simulations were conducted to elucidate the biophysical aspects of the Omicron spike protein's receptor-binding domain (RBD) in its interaction with human angiotensin-converting enzyme 2 (hACE2) and a neutralizing antibody, comparing it to the wildtype (WT). To model the Omicron variant, 15 in silico mutations were introduced in the RBD region of WT (retrieved from PDB). The simulations of WT spike-hACE2 and Omicron spike-hACE2 complexes revealed comparable binding stability and dynamics. Notably, the Q493R mutation in the Omicron spike increased interactions with hACE2, particularly with ASP38 and ASP355. Additionally, mutations such as N417K, T478K, and Y505H contributed to enhanced structural stability in the Omicron variant. Conversely, when comparing WT with Omicron in complex with a neutralizing antibody, simulation results demonstrated poorer binding dynamics and stability for the Omicron variant. The E484K mutation significantly decreased binding interactions, resulting in an overall decrease in binding energy (∼−57 kcal/mol) compared to WT (∼−84 kcal/mol). This study provides valuable molecular insights into the heightened infectivity of the Omicron variant, shedding light on the specific mutations influencing its interactions with hACE2 and neutralizing antibodies.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108087"},"PeriodicalIF":3.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140143707","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":"Optimal 3D angular sampling with applications to cryo-EM problems","authors":"Valeriy Titarenko ,&nbsp;Alan M. Roseman","doi":"10.1016/j.jsb.2024.108083","DOIUrl":"10.1016/j.jsb.2024.108083","url":null,"abstract":"<div><p>The goal of cryo-EM experiments in the biological sciences is to determine the atomic structure of a molecule and deduce insights into its functions and mechanisms. Despite improvements in instrumentation for data collection and new software algorithms, in most cases, individual atoms are not resolved. Model building of proteins, nucleic acids, or molecules in general, is feasible from the experimentally determined density maps at resolutions up to the range of 3–4 Angstroms. For lower-resolution maps or parts of maps, fitting smaller structures obtained by modelling or experimental techniques with higher resolution is a way to resolve the issue. In practice, we have an atomic structure, generate its density map at a given resolution, and translate/rotate the map within a region of interest in the experimental map, computing a measure-of-fit score with the corresponding areas of the experimental map. This procedure is computationally intensive since we work in 6D space. An optimal ordered list of rotations will reduce the angular error and help to find the best-fitting positions faster for a coarse global search or a local refinement. It can be used for adaptive approaches to stop fitting algorithms earlier once the desired accuracy has been achieved. We demonstrate how the performance of some fitting algorithms can be improved by grouping sets of rotations. We present an approach to generate more efficient 3D angular sampling, and provide the computer code to generate lists of optimal orientations for single and grouped rotations and the lists themselves.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108083"},"PeriodicalIF":3.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1047847724000236/pdfft?md5=7e1e2d9ef741145f9751aeb796e70580&pid=1-s2.0-S1047847724000236-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140136899","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":"Tooth acellular extrinsic fibre cementum incremental lines in humans are formed by parallel branched Sharpey’s fibres and not by its mineral phase","authors":"Lourdes R. Couoh ,&nbsp;Lauro Bucio ,&nbsp;José Luis Ruvalcaba ,&nbsp;Britta Manoel ,&nbsp;Tengteng Tang ,&nbsp;Aurélien Gourrier ,&nbsp;Kathryn Grandfield","doi":"10.1016/j.jsb.2024.108084","DOIUrl":"10.1016/j.jsb.2024.108084","url":null,"abstract":"<div><p>In humans, the growth pattern of the acellular extrinsic fibre cementum (AEFC) has been useful to estimate the age-at-death. However, the structural organization behind such a pattern remains poorly understood. In this study tooth cementum from seven individuals from a Mexican modern skeletal series were analyzed with the aim of unveiling the AEFC collagenous and mineral structure using multimodal imaging approaches. The organization of collagen fibres was first determined using: light microscopy, transmission electron microscopy (TEM), electron tomography, and plasma FIB scanning electron microscopy (PFIB-SEM) tomography. The mineral properties were then investigated using: synchrotron small-angle X-ray scattering (SAXS) for <em>T</em>-parameter (correlation length between mineral particles); synchrotron X-ray diffraction (XRD) for <em>L</em>-parameter (mineral crystalline domain size estimation), alignment parameter (crystals preferred orientation) and lattice parameters <em>a</em> and <em>c</em>; as well as synchrotron X-ray fluorescence for spatial distribution of calcium, phosphorus and zinc. Results show that Sharpey’s fibres branched out fibres that cover and uncover other collagen bundles forming aligned arched structures that are joined by these same fibres but in a parallel fashion. The parallel fibres are not set as a continuum on the same plane and when they are superimposed project the AEFC incremental lines due to the collagen birefringence. The orientation of the apatite crystallites is subject to the arrangement of the collagen fibres, and the obtained parameter values along with the elemental distribution maps, revealed this mineral tissue as relatively homogeneous. Therefore, no intrinsic characteristics of the mineral phase could be associated with the alternating AEFC incremental pattern.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108084"},"PeriodicalIF":3.0,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1047847724000248/pdfft?md5=c1309a961c2032bcfd5f02aeb90fc4f0&pid=1-s2.0-S1047847724000248-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140119861","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 Xylanase A double mutation on substrate specificity and structural dynamics","authors":"Meagan E. MacDonald ,&nbsp;Nicholas G.M. Wells ,&nbsp;Bakar A. Hassan ,&nbsp;Joshua A. Dudley ,&nbsp;Kylie J. Walters ,&nbsp;Dmitry M. Korzhnev ,&nbsp;James M. Aramini ,&nbsp;Colin A. Smith","doi":"10.1016/j.jsb.2024.108082","DOIUrl":"10.1016/j.jsb.2024.108082","url":null,"abstract":"<div><p>While protein activity is traditionally studied with a major focus on the active site, the activity of enzymes has been hypothesized to be linked to the flexibility of adjacent regions, warranting more exploration into how the dynamics in these regions affects catalytic turnover. One such enzyme is Xylanase A (XylA), which cleaves hemicellulose xylan polymers by hydrolysis at internal β-1,4-xylosidic linkages. It contains a “thumb” region whose flexibility has been suggested to affect the activity. The double mutation D11F/R122D was previously found to affect activity and potentially bias the thumb region to a more open conformation. We find that the D11F/R122D double mutation shows substrate-dependent effects, increasing activity on the non-native substrate ONPX2 but decreasing activity on its native xylan substrate. To characterize how the double mutant causes these kinetics changes, nuclear magnetic resonance (NMR) and molecular dynamics (MD) simulations were used to probe structural and flexibility changes. NMR chemical shift perturbations revealed structural changes in the double mutant relative to the wild-type, specifically in the thumb and fingers regions. Increased slow-timescale dynamics in the fingers region was observed as intermediate-exchange line broadening. Lipari-Szabo order parameters show negligible changes in flexibility in the thumb region in the presence of the double mutation. To help understand if there is increased energetic accessibility to the open state upon mutation, alchemical free energy simulations were employed that indicated thumb opening is more favorable in the double mutant. These studies aid in further characterizing how flexibility in adjacent regions affects the function of XylA.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108082"},"PeriodicalIF":3.0,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140028306","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":"Deep generative priors for biomolecular 3D heterogeneous reconstruction from cryo-EM projections","authors":"Bin Shi ,&nbsp;Kevin Zhang ,&nbsp;David J. Fleet ,&nbsp;Robert A. McLeod ,&nbsp;R.J. Dwayne Miller ,&nbsp;Jane Y. Howe","doi":"10.1016/j.jsb.2024.108073","DOIUrl":"10.1016/j.jsb.2024.108073","url":null,"abstract":"<div><p>Cryo-electron microscopy has become a powerful tool to determine three-dimensional (3D) structures of rigid biological macromolecules from noisy micrographs with single-particle reconstruction. Recently, deep neural networks, e.g., CryoDRGN, have demonstrated conformational and compositional heterogeneity of complexes. However, the lack of ground-truth conformations poses a challenge to assess the performance of heterogeneity analysis methods. In this work, variational autoencoders (VAE) with three types of deep generative priors were learned for latent variable inference and heterogeneous 3D reconstruction via Bayesian inference. More specifically, VAEs with “Variational Mixture of Posteriors” priors (VampPrior-SPR), non-parametric exemplar-based priors (ExemplarPrior-SPR) and priors from latent score-based generative models (LSGM-SPR) were quantitatively compared with CryoDRGN. We built four simulated datasets composed of hypothetical continuous conformation or discrete states of the hERG K + channel. Empirical and quantitative comparisons of inferred latent representations were performed with affine-transformation-based metrics. These models with more informative priors gave better regularized, interpretable factorized latent representations with better conserved pairwise distances, less deformed latent distributions and lower within-cluster variances. They were also tested on experimental datasets to resolve compositional and conformational heterogeneity (50S ribosome assembly, cowpea chlorotic mottle virus, and pre-catalytic spliceosome) with comparable high resolution. Codes and data are available: https://github.com/benjamin3344/DGP-SPR.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108073"},"PeriodicalIF":3.0,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1047847724000133/pdfft?md5=3206ac69857bd12de4ee871dac621d47&pid=1-s2.0-S1047847724000133-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140022084","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":"Tropomyosin induces the synthesis of magnesian calcite in sea urchin spines","authors":"Yugo Kato ,&nbsp;Woosuk Ha ,&nbsp;Zehua Zheng ,&nbsp;Lumi Negishi ,&nbsp;Jun Kawano ,&nbsp;Yoshihisa Kurita ,&nbsp;Hitoshi Kurumizaka ,&nbsp;Michio Suzuki","doi":"10.1016/j.jsb.2024.108074","DOIUrl":"10.1016/j.jsb.2024.108074","url":null,"abstract":"<div><p>Calcium carbonate is present in many biominerals, including in the exoskeletons of crustaceans and shells of mollusks. High Mg-containing calcium carbonate was synthesized by high temperatures, high pressures or high molecular organic matter. For example, biogenic high Mg-containing calcite is synthesized under strictly controlled Mg concentration at ambient temperature and pressure. The spines of sea urchins consist of calcite, which contain a high percentage of magnesium. In this study, we investigated the factors that increase the magnesium content in calcite from the spines of the sea urchin, <em>Heliocidaris crassispina</em>. X-ray diffraction and inductively coupled plasma mass spectrometry analyses showed that sea urchin spines contain about 4.8% Mg. The organic matrix extracted from the <em>H. crassispina</em> spines induced the crystallization of amorphous phase and synthesis of magnesium-containing calcite, while amorphous was synthesized without SUE (sea urchin extract). In addition, aragonite was synthesized by SUE treated with protease-K. HC tropomyosin was specifically incorporated into Mg precipitates. Recombinant HC-tropomyosin induced calcite contained 0.1–2.5% Mg synthesis. Western blotting of sea urchin spine extracts confirmed that HC tropomyosin was present in the purple sea urchin spines at a protein weight ratio of 1.5%. These results show that HC tropomyosin is one factor that increases the magnesium concentration in the calcite of <em>H</em>. <em>crassispina</em> spines.</p></div>","PeriodicalId":17074,"journal":{"name":"Journal of structural biology","volume":"216 2","pages":"Article 108074"},"PeriodicalIF":3.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140021985","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}