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Cai J, Yun Q, Zhang CY, Wang Z, Hinshaw SM, Zhou H, Suhandynata RT. Concatemer Assisted Stoichiometry Analysis (CASA): targeted mass spectrometry for protein quantification. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.26.605382. [PMID: 39091769 PMCID: PMC11291133 DOI: 10.1101/2024.07.26.605382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Large multi-protein machines are central to multiple biological processes. However, stoichiometric determination of protein complex subunits in their native states presents a significant challenge. This study addresses the limitations of current tools in accuracy and precision by introducing concatemer-assisted stoichiometry analysis (CASA). CASA leverages stable isotope-labeled concatemers and liquid chromatography parallel reaction monitoring mass spectrometry (LC-PRM-MS) to achieve robust quantification of proteins with sub-femtomole sensitivity. As a proof-of-concept, CASA was applied to study budding yeast kinetochores. Stoichiometries were determined for ex vivo reconstituted kinetochore components, including the canonical H3 nucleosomes, centromeric (Cse4CENP-A) nucleosomes, centromere proximal factors (Cbf1 and CBF3 complex), inner kinetochore proteins (Mif2CENP-C, Ctf19CCAN complex), and outer kinetochore proteins (KMN network). Absolute quantification by CASA revealed Cse4CENP-A as a cell-cycle controlled limiting factor for kinetochore assembly. These findings demonstrate that CASA is applicable for stoichiometry analysis of multi-protein assemblies.
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Affiliation(s)
- Jiaxi Cai
- Department of Cellular and Molecular Medicine, University of California, San Diego, California
- Department of Bioengineering, University of California, San Diego, California
| | - Quan Yun
- Department of Cellular and Molecular Medicine, University of California, San Diego, California
| | - Cindy Yuxuan Zhang
- Department of Cellular and Molecular Medicine, University of California, San Diego, California
| | - Ziyi Wang
- Department of Cellular and Molecular Medicine, University of California, San Diego, California
| | - Stephen M. Hinshaw
- Department of Chemical and Systems Biology, Stanford University, Palo Alto, California
| | - Huilin Zhou
- Department of Cellular and Molecular Medicine, University of California, San Diego, California
- Department of Bioengineering, University of California, San Diego, California
- Moores Cancer Center, University of California, San Diego, California
| | - Raymond T. Suhandynata
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, California
- Department of Pathology, University of California, San Diego, California
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2
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Blundon JM, Cesar BI, Bae JW, Čavka I, Haversat J, Ries J, Köhler S, Kim Y. Skp1 proteins are structural components of the synaptonemal complex in C. elegans. SCIENCE ADVANCES 2024; 10:eadl4876. [PMID: 38354250 PMCID: PMC10866564 DOI: 10.1126/sciadv.adl4876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/12/2024] [Indexed: 02/16/2024]
Abstract
The synaptonemal complex (SC) is a zipper-like protein assembly that links homologous chromosomes to regulate recombination and segregation during meiosis. The SC has been notoriously refractory to in vitro reconstitution, thus leaving its molecular organization largely unknown. Here, we report a moonlighting function of two paralogous S-phase kinase-associated protein 1 (Skp1)-related proteins (SKR-1 and SKR-2), well-known adaptors of the Skp1-Cul1-F-box (SCF) ubiquitin ligase, as the key missing components of the SC in Caenorhabditis elegans. SKR proteins repurpose their SCF-forming interfaces to dimerize and interact with meiosis-specific SC proteins, thereby driving synapsis independent of SCF activity. SKR-1 enables the formation of the long-sought-after soluble complex with previously identified SC proteins in vitro, which we propose it to represent a complete SC building block. Our findings demonstrate how a conserved cell cycle regulator has been co-opted to interact with rapidly evolving meiotic proteins to construct the SC and provide a foundation for understanding its structure and assembly mechanisms.
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Affiliation(s)
- Joshua M. Blundon
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Brenda I. Cesar
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jung Woo Bae
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Ivana Čavka
- The European Molecular Biology Laboratory, Heidelberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Jocelyn Haversat
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jonas Ries
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Simone Köhler
- The European Molecular Biology Laboratory, Heidelberg, Germany
| | - Yumi Kim
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
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3
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Popchock AR, Larson JD, Dubrulle J, Asbury CL, Biggins S. Direct observation of coordinated assembly of individual native centromeric nucleosomes. EMBO J 2023; 42:e114534. [PMID: 37469281 PMCID: PMC10476280 DOI: 10.15252/embj.2023114534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/27/2023] [Accepted: 07/04/2023] [Indexed: 07/21/2023] Open
Abstract
Eukaryotic chromosome segregation requires the kinetochore, a megadalton-sized machine that forms on specialized centromeric chromatin containing CENP-A, a histone H3 variant. CENP-A deposition requires a chaperone protein HJURP that targets it to the centromere, but it has remained unclear whether HJURP has additional functions beyond CENP-A targeting and why high AT DNA content, which disfavors nucleosome assembly, is widely conserved at centromeres. To overcome the difficulties of studying nucleosome formation in vivo, we developed a microscopy assay that enables direct observation of de novo centromeric nucleosome recruitment and maintenance with single molecule resolution. Using this assay, we discover that CENP-A can arrive at centromeres without its dedicated centromere-specific chaperone HJURP, but stable incorporation depends on HJURP and additional DNA-binding proteins of the inner kinetochore. We also show that homopolymer AT runs in the yeast centromeres are essential for efficient CENP-A deposition. Together, our findings reveal requirements for stable nucleosome formation and provide a foundation for further studies of the assembly and dynamics of native kinetochore complexes.
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Affiliation(s)
- Andrew R Popchock
- Basic Sciences Division, Howard Hughes Medical InstituteFred Hutchinson Cancer CenterSeattleWAUSA
| | - Joshua D Larson
- Department of Physiology and BiophysicsUniversity of WashingtonSeattleWAUSA
| | | | - Charles L Asbury
- Department of Physiology and BiophysicsUniversity of WashingtonSeattleWAUSA
| | - Sue Biggins
- Basic Sciences Division, Howard Hughes Medical InstituteFred Hutchinson Cancer CenterSeattleWAUSA
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4
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Dendooven T, Zhang Z, Yang J, McLaughlin SH, Schwab J, Scheres SHW, Yatskevich S, Barford D. Cryo-EM structure of the complete inner kinetochore of the budding yeast point centromere. SCIENCE ADVANCES 2023; 9:eadg7480. [PMID: 37506202 PMCID: PMC10381965 DOI: 10.1126/sciadv.adg7480] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023]
Abstract
The point centromere of budding yeast specifies assembly of the large kinetochore complex to mediate chromatid segregation. Kinetochores comprise the centromere-associated inner kinetochore (CCAN) complex and the microtubule-binding outer kinetochore KNL1-MIS12-NDC80 (KMN) network. The budding yeast inner kinetochore also contains the DNA binding centromere-binding factor 1 (CBF1) and CBF3 complexes. We determined the cryo-electron microscopy structure of the yeast inner kinetochore assembled onto the centromere-specific centromere protein A nucleosomes (CENP-ANuc). This revealed a central CENP-ANuc with extensively unwrapped DNA ends. These free DNA duplexes bind two CCAN protomers, one of which entraps DNA topologically, positioned on the centromere DNA element I (CDEI) motif by CBF1. The two CCAN protomers are linked through CBF3 forming an arch-like configuration. With a structural mechanism for how CENP-ANuc can also be linked to KMN involving only CENP-QU, we present a model for inner kinetochore assembly onto a point centromere and how it organizes the outer kinetochore for chromosome attachment to the mitotic spindle.
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Affiliation(s)
| | | | - Jing Yang
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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5
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Popchock AR, Larson JD, Dubrulle J, Asbury CL, Biggins S. Direct observation of coordinated assembly of individual native centromeric nucleosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524981. [PMID: 36711558 PMCID: PMC9882320 DOI: 10.1101/2023.01.20.524981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Eukaryotic chromosome segregation requires the kinetochore, a megadalton-sized machine that forms on specialized centromeric chromatin containing CENP-A, a histone H3 variant. CENP-A deposition requires a chaperone protein HJURP that targets it to the centromere, but it has remained unclear whether HJURP has additional functions beyond CENP-A targeting and why high AT DNA content, which disfavors nucleosome assembly, is widely conserved at centromeres. To overcome the difficulties of studying nucleosome formation in vivo, we developed a microscopy assay that enables direct observation of de novo centromeric nucleosome recruitment and maintenance with single molecule resolution. Using this assay, we discover that CENP-A can arrive at centromeres without its dedicated centromere-specific chaperone HJURP, but stable incorporation depends on HJURP and additional DNA-binding proteins of the inner kinetochore. We also show that homopolymer AT runs in the yeast centromeres are essential for efficient CENP-A deposition. Together, our findings reveal requirements for stable nucleosome formation and provide a foundation for further studies of the assembly and dynamics of native kinetochore complexes.
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Affiliation(s)
- Andrew R. Popchock
- Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Joshua D. Larson
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Julien Dubrulle
- Shared Resources, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Charles L. Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Sue Biggins
- Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
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6
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Cieslinski K, Wu YL, Nechyporenko L, Hörner SJ, Conti D, Skruzny M, Ries J. Nanoscale structural organization and stoichiometry of the budding yeast kinetochore. J Cell Biol 2023; 222:213833. [PMID: 36705601 PMCID: PMC9929930 DOI: 10.1083/jcb.202209094] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 12/16/2022] [Accepted: 12/27/2022] [Indexed: 01/28/2023] Open
Abstract
Proper chromosome segregation is crucial for cell division. In eukaryotes, this is achieved by the kinetochore, an evolutionarily conserved multiprotein complex that physically links the DNA to spindle microtubules and takes an active role in monitoring and correcting erroneous spindle-chromosome attachments. Our mechanistic understanding of these functions and how they ensure an error-free outcome of mitosis is still limited, partly because we lack a complete understanding of the kinetochore structure in the cell. In this study, we use single-molecule localization microscopy to visualize individual kinetochore complexes in situ in budding yeast. For major kinetochore proteins, we measured their abundance and position within the metaphase kinetochore. Based on this comprehensive dataset, we propose a quantitative model of the budding yeast kinetochore. While confirming many aspects of previous reports based on bulk imaging, our results present a unifying nanoscale model of the kinetochore in budding yeast.
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Affiliation(s)
- Konstanty Cieslinski
- https://ror.org/03mstc592Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany,Translational Radiation Oncology Unit, Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Yu-Le Wu
- https://ror.org/03mstc592Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany,Faculty of Biosciences, Collaboration for Joint PhD Degree Between European Molecular Biology Laboratory and Heidelberg University, Heidelberg, Germany
| | - Lisa Nechyporenko
- https://ror.org/03mstc592Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany,Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Sarah Janice Hörner
- https://ror.org/03mstc592Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany,https://ror.org/04p61dj41Institute of Molecular and Cell Biology, Mannheim University of Applied Sciences, Mannheim, Germany,Interdisciplinary Center for Neuroscience, Heidelberg University, Heidelberg, Germany
| | - Duccio Conti
- https://ror.org/03vpj4s62Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Michal Skruzny
- https://ror.org/03mstc592Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jonas Ries
- https://ror.org/03mstc592Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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7
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Cell-cycle phospho-regulation of the kinetochore. Curr Genet 2021; 67:177-193. [PMID: 33221975 DOI: 10.1007/s00294-020-01127-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 02/07/2023]
Abstract
The kinetochore is a mega-dalton protein assembly that forms within centromeric regions of chromosomes and directs their segregation during cell division. Here we review cell cycle-mediated phosphorylation events at the kinetochore, with a focus on the budding yeast Saccharomyces cerevisiae and the insight gained from forced associations of kinases and phosphatases. The point centromeres found in the budding yeast S. cerevisiae are one of the simplest such structures found in eukaryotes. The S. cerevisiae kinetochore comprises a single nucleosome, containing a centromere-specific H3 variant Cse4CENP-A, bound to a set of kinetochore proteins that connect to a single microtubule. Despite the simplicity of the budding yeast kinetochore, the proteins are mostly homologous with their mammalian counterparts. In some cases, human proteins can complement their yeast orthologs. Like its mammalian equivalent, the regulation of the budding yeast kinetochore is complex: integrating signals from the cell cycle, checkpoints, error correction, and stress pathways. The regulatory signals from these diverse pathways are integrated at the kinetochore by post-translational modifications, notably phosphorylation and dephosphorylation, to control chromosome segregation. Here we highlight the complex interplay between the activity of the different cell-cycle kinases and phosphatases at the kinetochore, emphasizing how much more we have to understand this essential structure.
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8
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Structural and dynamic mechanisms of CBF3-guided centromeric nucleosome formation. Nat Commun 2021; 12:1763. [PMID: 33741944 PMCID: PMC7979930 DOI: 10.1038/s41467-021-21985-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 02/22/2021] [Indexed: 11/08/2022] Open
Abstract
Accurate chromosome segregation relies on the specific centromeric nucleosome-kinetochore interface. In budding yeast, the centromere CBF3 complex guides the deposition of CENP-A, an H3 variant, to form the centromeric nucleosome in a DNA sequence-dependent manner. Here, we determine the structures of the centromeric nucleosome containing the native CEN3 DNA and the CBF3core bound to the canonical nucleosome containing an engineered CEN3 DNA. The centromeric nucleosome core structure contains 115 base pair DNA including a CCG motif. The CBF3core specifically recognizes the nucleosomal CCG motif through the Gal4 domain while allosterically altering the DNA conformation. Cryo-EM, modeling, and mutational studies reveal that the CBF3core forms dynamic interactions with core histones H2B and CENP-A in the CEN3 nucleosome. Our results provide insights into the structure of the budding yeast centromeric nucleosome and the mechanism of its assembly, which have implications for analogous processes of human centromeric nucleosome formation.
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9
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Kim HW, Eletsky A, Gonzalez KJ, van der Wel H, Strauch EM, Prestegard JH, West CM. Skp1 Dimerization Conceals Its F-Box Protein Binding Site. Biochemistry 2020; 59:1527-1536. [PMID: 32227851 PMCID: PMC7521599 DOI: 10.1021/acs.biochem.0c00094] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Skp1 is an adapter that links F-box proteins to cullin-1 in the Skp1/cullin-1/F-box (SCF) protein family of E3 ubiquitin ligases that targets specific proteins for polyubiquitination and subsequent protein degradation. Skp1 from the amoebozoan Dictyostelium forms a stable homodimer in vitro with a Kd of 2.5 μM as determined by sedimentation velocity studies yet is monomeric in crystal complexes with F-box proteins. To investigate the molecular basis for the difference, we determined the solution NMR structure of a doubly truncated Skp1 homodimer (Skp1ΔΔ). The solution structure of the Skp1ΔΔ dimer reveals a 2-fold symmetry with an interface that buries ∼750 Å2 of predominantly hydrophobic surface. The dimer interface overlaps with subsite 1 of the F-box interaction area, explaining why only the Skp1 monomer binds F-box proteins (FBPs). To confirm the model, Rosetta was used to predict amino acid substitutions that might disrupt the dimer interface, and the F97E substitution was chosen to potentially minimize interference with F-box interactions. A nearly full-length version of Skp1 with this substitution (Skp1ΔF97E) behaved as a stable monomer at concentrations of ≤500 μM and actively bound a model FBP, mammalian Fbs1, which suggests that the dimeric state is not required for Skp1 to carry out a basic biochemical function. Finally, Skp1ΔF97E is expected to serve as a monomer model for high-resolution NMR studies previously hindered by dimerization.
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Affiliation(s)
- Hyun W. Kim
- Dept. of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602 USA
| | - Alexander Eletsky
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 USA
| | - Karen J. Gonzalez
- Dept. of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602 USA
| | - Hanke van der Wel
- Dept. of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602 USA
| | - Eva-Maria Strauch
- Dept. of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA 30602 USA
| | - James H. Prestegard
- Dept. of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602 USA
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 USA
| | - Christopher M. West
- Dept. of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602 USA
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 USA
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602 USA
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10
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Ng CT, Gan L. Investigating eukaryotic cells with cryo-ET. Mol Biol Cell 2020; 31:87-100. [PMID: 31935172 PMCID: PMC6960407 DOI: 10.1091/mbc.e18-05-0329] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 11/25/2019] [Accepted: 11/29/2019] [Indexed: 01/06/2023] Open
Abstract
The interior of eukaryotic cells is mysterious. How do the large communities of macromolecular machines interact with each other? How do the structures and positions of these nanoscopic entities respond to new stimuli? Questions like these can now be answered with the help of a method called electron cryotomography (cryo-ET). Cryo-ET will ultimately reveal the inner workings of a cell at the protein, secondary structure, and perhaps even side-chain levels. Combined with genetic or pharmacological perturbation, cryo-ET will allow us to answer previously unimaginable questions, such as how structure, biochemistry, and forces are related in situ. Because it bridges structural biology and cell biology, cryo-ET is indispensable for structural cell biology-the study of the 3-D macromolecular structure of cells. Here we discuss some of the key ideas, strategies, auxiliary techniques, and innovations that an aspiring structural cell biologist will consider when planning to ask bold questions.
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Affiliation(s)
- Cai Tong Ng
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543
| | - Lu Gan
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore 117543
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11
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Baptista CG, Lis A, Deng B, Gas-Pascual E, Dittmar A, Sigurdson W, West CM, Blader IJ. Toxoplasma F-box protein 1 is required for daughter cell scaffold function during parasite replication. PLoS Pathog 2019; 15:e1007946. [PMID: 31348812 PMCID: PMC6685633 DOI: 10.1371/journal.ppat.1007946] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 08/07/2019] [Accepted: 06/27/2019] [Indexed: 01/06/2023] Open
Abstract
By binding to the adaptor protein SKP1 and serving as substrate receptors for the SKP1 Cullin, F-box E3 ubiquitin ligase complex, F-box proteins regulate critical cellular processes including cell cycle progression and membrane trafficking. While F-box proteins are conserved throughout eukaryotes and are well studied in yeast, plants, and animals, studies in parasitic protozoa are lagging. We have identified eighteen putative F-box proteins in the Toxoplasma genome of which four have predicted homologs in Plasmodium. Two of the conserved F-box proteins were demonstrated to be important for Toxoplasma fitness and here we focus on an F-box protein, named TgFBXO1, because it is the most highly expressed by replicative tachyzoites and was also identified in an interactome screen as a Toxoplasma SKP1 binding protein. TgFBXO1 interacts with Toxoplasma SKP1 confirming it as a bona fide F-box protein. In interphase parasites, TgFBXO1 is a component of the Inner Membrane Complex (IMC), which is an organelle that underlies the plasma membrane. Early during replication, TgFBXO1 localizes to the developing daughter cell scaffold, which is the site where the daughter cell IMC and microtubules form and extend from. TgFBXO1 localization to the daughter cell scaffold required centrosome duplication but before kinetochore separation was completed. Daughter cell scaffold localization required TgFBXO1 N-myristoylation and was dependent on the small molecular weight GTPase, TgRab11b. Finally, we demonstrate that TgFBXO1 is required for parasite growth due to its function as a daughter cell scaffold effector. TgFBXO1 is the first F-box protein to be studied in apicomplexan parasites and represents the first protein demonstrated to be important for daughter cell scaffold function.
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Affiliation(s)
- Carlos Gustavo Baptista
- Department of Microbiology and Immunology, University at Buffalo School of Medicine, Buffalo, New York, United States of America
| | - Agnieszka Lis
- Department of Microbiology and Immunology, University at Buffalo School of Medicine, Buffalo, New York, United States of America
| | - Bowen Deng
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Elisabet Gas-Pascual
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Ashley Dittmar
- Department of Microbiology and Immunology, University at Buffalo School of Medicine, Buffalo, New York, United States of America
| | - Wade Sigurdson
- Department of Physiology and Biophysics, University at Buffalo School of Medicine, Buffalo, New York, United States of America
| | - Christopher M. West
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Ira J. Blader
- Department of Microbiology and Immunology, University at Buffalo School of Medicine, Buffalo, New York, United States of America
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12
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West CM, Kim HW. Nucleocytoplasmic O-glycosylation in protists. Curr Opin Struct Biol 2019; 56:204-212. [PMID: 31128470 DOI: 10.1016/j.sbi.2019.03.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 03/19/2019] [Accepted: 03/31/2019] [Indexed: 12/17/2022]
Abstract
O-Glycosylation is an increasingly recognized modification of intracellular proteins in all kingdoms of life, and its occurrence in protists has been investigated to understand its evolution and its roles in the virulence of unicellular pathogens. We focus here on two kinds of glycoregulation found in unicellular eukaryotes: one is a simple O-fucose modification of dozens if not hundreds of Ser/Thr-rich proteins, and the other a complex pentasaccharide devoted to a single protein associated with oxygen sensing and the assembly of polyubiquitin chains. These modifications are not required for life but contingently modulate biological processes in the social amoeba Dictyostelium and the human pathogen Toxoplasma gondii, and likely occur in diverse unicellular protists. O-Glycosylation that is co-localized in the cytoplasm allows for glycoregulation over the entire life of the protein, contrary to the secretory pathway where glycosylation usually occurs before its delivery to its site of function. Here, we interpret cellular roles of nucleocytoplasmic glycans in terms of current evidence for their effects on the conformation and dynamics of protist proteins, to serve as a guide for future studies to examine their broader significance.
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Affiliation(s)
- Christopher M West
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA 30602 USA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602 USA; Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 USA.
| | - Hyun W Kim
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA 30602 USA
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13
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Hamilton G, Dimitrova Y, Davis TN. Seeing is believing: our evolving view of kinetochore structure, composition, and assembly. Curr Opin Cell Biol 2019; 60:44-52. [PMID: 31078123 DOI: 10.1016/j.ceb.2019.03.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/20/2019] [Accepted: 03/28/2019] [Indexed: 11/26/2022]
Abstract
This review highlights three recent trends in the field of kinetochore biology: the proliferation of structural data for kinetochore protein complexes (including CBF3, Dam1c, Mis12cMIND, and CENP-NLChl4/Iml3); the growing consensus that the kinetochore is a dynamic structure whose composition changes as the cell cycle progresses; and the mounting evidence of multiple pathways whereby the microtubule-binding elements of the outer kinetochore may be recruited by inner kinetochore proteins. Our focus is on the two best-studied systems in the field: human and budding yeast kinetochores. This review will demonstrate the remarkable similarity of these two systems, as well as their intriguing differences.
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Affiliation(s)
- Grace Hamilton
- Department of Biochemistry, University of Washington Box 357350, 1705 NE Pacific St., Seattle, WA 98195-7350, USA
| | - Yoana Dimitrova
- Genentech, Inc., 1 DNA Way, MS: 27, South San Francisco, CA 94080, USA
| | - Trisha N Davis
- Department of Biochemistry, University of Washington Box 357350, 1705 NE Pacific St., Seattle, WA 98195-7350, USA.
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Yan K, Zhang Z, Yang J, McLaughlin SH, Barford D. Architecture of the CBF3-centromere complex of the budding yeast kinetochore. Nat Struct Mol Biol 2018; 25:1103-1110. [PMID: 30478265 PMCID: PMC6292502 DOI: 10.1038/s41594-018-0154-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/10/2018] [Indexed: 01/01/2023]
Abstract
Kinetochores are multicomponent complexes responsible for coordinating the attachment of centromeric DNA to mitotic-spindle microtubules. The point centromeres of budding yeast are organized into three centromeric determining elements (CDEs), and are associated with the centromere-specific nucleosome Cse4. Deposition of Cse4 at CEN loci is dependent on the CBF3 complex that engages CDEIII to direct Cse4 nucleosomes to CDEII. To understand how CBF3 recognizes CDEIII and positions Cse4, we determined a cryo-EM structure of a CBF3-CEN complex. CBF3 interacts with CEN DNA as a head-to-head dimer that includes the whole of CDEIII and immediate 3' regions. Specific CEN-binding of CBF3 is mediated by a Cep3 subunit of one of the CBF3 protomers that forms major groove interactions with the conserved and essential CCG and TGT motifs of CDEIII. We propose a model for a CBF3-Cse4-CEN complex with implications for understanding CBF3-directed deposition of the Cse4 nucleosome at CEN loci.
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Affiliation(s)
- Kaige Yan
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Ziguo Zhang
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Jing Yang
- MRC Laboratory of Molecular Biology, Cambridge, UK
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15
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Zhang W, Lukoyanova N, Miah S, Lucas J, Vaughan CK. Insights into Centromere DNA Bending Revealed by the Cryo-EM Structure of the Core Centromere Binding Factor 3 with Ndc10. Cell Rep 2018; 24:744-754. [PMID: 30021170 PMCID: PMC6077249 DOI: 10.1016/j.celrep.2018.06.068] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/06/2018] [Accepted: 06/15/2018] [Indexed: 12/21/2022] Open
Abstract
The centromere binding factor 3 (CBF3) complex binds the third centromere DNA element in organisms with point centromeres, such as S. cerevisiae. It is an essential complex for assembly of the kinetochore in these organisms, as it facilitates genetic centromere specification and allows association of all other kinetochore components. We determined high-resolution structures of the core complex of CBF3 alone and in association with a monomeric construct of Ndc10, using cryoelectron microscopy (cryo-EM). We identify the DNA-binding site of the complex and present a model in which CBF3 induces a tight bend in centromeric DNA, thus facilitating assembly of the centromeric nucleosome. Cryo-EM studies of CBF3 reveal the core complex has a deep asymmetric channel The size, conservation, and charge of the channel suggest that it binds centromere DNA Unique insertions in the Ctf13 F box provide the binding site for one Ndc10 monomer The Ndc10 DNA-binding site is in plane with and perpendicular to the CBF3 channel
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Affiliation(s)
- Wenjuan Zhang
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, UK; Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Natalya Lukoyanova
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Shomon Miah
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, UK
| | - Jonathan Lucas
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Cara K Vaughan
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, UK; Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
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16
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Leber V, Nans A, Singleton MR. Structural basis for assembly of the CBF3 kinetochore complex. EMBO J 2018; 37:269-281. [PMID: 29212814 PMCID: PMC5771398 DOI: 10.15252/embj.201798134] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/30/2017] [Accepted: 11/20/2017] [Indexed: 11/09/2022] Open
Abstract
Eukaryotic chromosomes contain a specialised region known as the centromere, which forms the platform for kinetochore assembly and microtubule attachment. The centromere is distinguished by the presence of nucleosomes containing the histone H3 variant, CENP-A. In budding yeast, centromere establishment begins with the recognition of a specific DNA sequence by the CBF3 complex. This in turn facilitates CENP-ACse4 nucleosome deposition and kinetochore assembly. Here, we describe a 3.6 Å single-particle cryo-EM reconstruction of the core CBF3 complex, incorporating the sequence-specific DNA-binding protein Cep3 together with regulatory subunits Ctf13 and Skp1. This provides the first structural data on Ctf13, defining it as an F-box protein of the leucine-rich-repeat family, and demonstrates how a novel F-box-mediated interaction between Ctf13 and Skp1 is responsible for initial assembly of the CBF3 complex.
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Affiliation(s)
- Vera Leber
- Structural Biology of Chromosome Segregation Laboratory, The Francis Crick Institute, London, UK
| | - Andrea Nans
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, UK
| | - Martin R Singleton
- Structural Biology of Chromosome Segregation Laboratory, The Francis Crick Institute, London, UK
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