1
|
Shintomi K, Masahara-Negishi Y, Shima M, Tane S, Hirano T. Recombinant cyclin B-Cdk1-Suc1 capable of multi-site mitotic phosphorylation in vitro. PLoS One 2024; 19:e0299003. [PMID: 38527022 PMCID: PMC10962838 DOI: 10.1371/journal.pone.0299003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 02/04/2024] [Indexed: 03/27/2024] Open
Abstract
Cyclin-dependent kinase 1 (Cdk1) complexed with cyclin B phosphorylates multiple sites on hundreds of proteins during mitosis. However, it is not fully understood how multi-site mitotic phosphorylation by cyclin B-Cdk1 controls the structures and functions of individual substrates. Here we develop an easy-to-use protocol to express recombinant vertebrate cyclin B and Cdk1 in insect cells from a single baculovirus vector and to purify their complexes with excellent homogeneity. A series of in-vitro assays demonstrate that the recombinant cyclin B-Cdk1 can efficiently and specifically phosphorylate the SP and TP motifs in substrates. The addition of Suc1 (a Cks1 homolog in fission yeast) accelerates multi-site phosphorylation of an artificial substrate containing TP motifs. Importantly, we show that mitosis-specific multi-subunit and multi-site phosphorylation of the condensin I complex can be recapitulated in vitro using recombinant cyclin B-Cdk1-Suc1. The materials and protocols described here will pave the way for dissecting the biochemical basis of critical mitotic processes that accompany Cdk1-mediated large-scale phosphorylation.
Collapse
Affiliation(s)
- Keishi Shintomi
- Chromosome Dynamics Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Yuki Masahara-Negishi
- Chromosome Dynamics Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Masami Shima
- Chromosome Dynamics Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Shoji Tane
- Chromosome Dynamics Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
| |
Collapse
|
2
|
Yoshida MM, Kinoshita K, Shintomi K, Aizawa Y, Hirano T. Regulation of condensin II by self-suppression and release mechanisms. Mol Biol Cell 2024; 35:ar21. [PMID: 38088875 PMCID: PMC10881152 DOI: 10.1091/mbc.e23-10-0392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 01/14/2024] Open
Abstract
In vertebrates, two distinct condensin complexes, condensin I and condensin II, cooperate to drive mitotic chromosome assembly. It remains largely unknown how the two complexes differentially contribute to this process at a mechanistic level. We have previously dissected the role of individual subunits of condensin II by introducing recombinant complexes into Xenopus egg extracts. Here we extend these efforts by introducing a modified functional assay using extracts depleted of topoisomerase IIα (topo IIα), which allows us to further elucidate the functional similarities and differences between condensin I and condensin II. The intrinsically disordered C-terminal region of the CAP-D3 subunit (the D3 C-tail) is a major target of Cdk1 phosphorylation, and phosphorylation-deficient mutations in this region impair condensin II functions. We also identify a unique helical structure in CAP-D3 (the D3 HEAT docker) that is predicted to directly interact with CAP-G2. Deletion of the D3 HEAT docker, along with the D3 C-tail, enhances the ability of condensin II to assemble mitotic chromosomes. Taken together, we propose a self-suppression mechanism unique to condensin II that is released by mitotic phosphorylation. Evolutionary implications of our findings are also discussed.
Collapse
Affiliation(s)
- Makoto M. Yoshida
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | | | - Keishi Shintomi
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Yuuki Aizawa
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| |
Collapse
|
3
|
Tang M, Pobegalov G, Tanizawa H, Chen ZA, Rappsilber J, Molodtsov M, Noma KI, Uhlmann F. Establishment of dsDNA-dsDNA interactions by the condensin complex. Mol Cell 2023; 83:3787-3800.e9. [PMID: 37820734 PMCID: PMC10842940 DOI: 10.1016/j.molcel.2023.09.019] [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: 05/08/2023] [Revised: 08/13/2023] [Accepted: 09/13/2023] [Indexed: 10/13/2023]
Abstract
Condensin is a structural maintenance of chromosomes (SMC) complex family member thought to build mitotic chromosomes by DNA loop extrusion. However, condensin variants unable to extrude loops, yet proficient in chromosome formation, were recently described. Here, we explore how condensin might alternatively build chromosomes. Using bulk biochemical and single-molecule experiments with purified fission yeast condensin, we observe that individual condensins sequentially and topologically entrap two double-stranded DNAs (dsDNAs). Condensin loading transitions through a state requiring DNA bending, as proposed for the related cohesin complex. While cohesin then favors the capture of a second single-stranded DNA (ssDNA), second dsDNA capture emerges as a defining feature of condensin. We provide complementary in vivo evidence for DNA-DNA capture in the form of condensin-dependent chromatin contacts within, as well as between, chromosomes. Our results support a "diffusion capture" model in which condensin acts in mitotic chromosome formation by sequential dsDNA-dsDNA capture.
Collapse
Affiliation(s)
- Minzhe Tang
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Georgii Pobegalov
- Mechanobiology and Biophysics Laboratory, The Francis Crick Institute, London NW1 1AT, UK; Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - Hideki Tanizawa
- Division of Genome Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan
| | - Zhuo A Chen
- Bioanalytics Unit, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany
| | - Juri Rappsilber
- Bioanalytics Unit, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany; Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Maxim Molodtsov
- Mechanobiology and Biophysics Laboratory, The Francis Crick Institute, London NW1 1AT, UK; Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - Ken-Ichi Noma
- Division of Genome Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK; Cell Biology Centre, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa 226-0026, Japan.
| |
Collapse
|
4
|
El Yakoubi W, Akera T. Condensin dysfunction is a reproductive isolating barrier in mice. Nature 2023; 623:347-355. [PMID: 37914934 DOI: 10.1038/s41586-023-06700-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 10/02/2023] [Indexed: 11/03/2023]
Abstract
Reproductive isolation occurs when the genomes of two populations accumulate genetic incompatibilities that prevent interbreeding1,2. Understanding of hybrid incompatibility at the cell biology level is limited, particularly in the case of hybrid female sterility3. Here we find that species divergence in condensin regulation and centromere organization between two mouse species, Mus musculus domesticus and Mus spretus, drives chromosome decondensation and mis-segregation in their F1 hybrid oocytes, reducing female fertility. The decondensation in hybrid oocytes was especially prominent at pericentromeric major satellites, which are highly abundant at M. m. domesticus centromeres4-6, leading to species-specific chromosome mis-segregation and egg aneuploidy. Consistent with the condensation defects, a chromosome structure protein complex, condensin II7,8, was reduced on hybrid oocyte chromosomes. We find that the condensin II subunit NCAPG2 was specifically reduced in the nucleus in prophase and that overexpressing NCAPG2 rescued both the decondensation and egg aneuploidy phenotypes. In addition to the overall reduction in condensin II on chromosomes, major satellites further reduced condensin II levels locally, explaining why this region is particularly prone to decondensation. Together, this study provides cell biological insights into hybrid incompatibility in female meiosis and demonstrates that condensin misregulation and pericentromeric satellite expansion can establish a reproductive isolating barrier in mammals.
Collapse
Affiliation(s)
- Warif El Yakoubi
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Takashi Akera
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| |
Collapse
|
5
|
Yamamoto T, Kinoshita K, Hirano T. Elasticity control of entangled chromosomes: Crosstalk between condensin complexes and nucleosomes. Biophys J 2023; 122:3869-3881. [PMID: 37571823 PMCID: PMC10560673 DOI: 10.1016/j.bpj.2023.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/18/2023] [Accepted: 08/08/2023] [Indexed: 08/13/2023] Open
Abstract
Condensin-mediated loop extrusion is now considered as the main driving force of mitotic chromosome assembly. Recent experiments have shown, however, that a class of mutant condensin complexes deficient in loop extrusion can assemble chromosome-like structures in Xenopus egg extracts, although these structures are somewhat different from those assembled by wild-type condensin complexes. In the absence of topoisomerase II (topo II), the mutant condensin complexes produce an unusual round-shaped structure termed a bean, which consists of a DNA-dense central core surrounded by a DNA-sparse halo. The mutant condensin complexes accumulate in the core, whereas histones are more concentrated in the halo than in the core. We consider that this peculiar structure serves as a model system to study how DNA entanglements, nucleosomes, and condensin functionally crosstalk with each other. To gain insight into how the bean structure is formed, here we construct a theoretical model. Our theory predicts that the core is formed by attractive interactions between mutant condensin complexes, whereas the halo is stabilized by the energy reduction through the selective accumulation of nucleosomes. The formation of the halo increases the elastic free energy due to the DNA entanglement in the core, but the latter free energy is compensated by condensin complexes that suppress the assembly of nucleosomes.
Collapse
Affiliation(s)
- Tetsuya Yamamoto
- Institute for Chemical Reaction Design and Discovery (ICReDD), Hokkaido University, Sapporo, Hokkaido, Japan.
| | | | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan
| |
Collapse
|
6
|
Regulation of the mitotic chromosome folding machines. Biochem J 2022; 479:2153-2173. [PMID: 36268993 DOI: 10.1042/bcj20210140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 09/30/2022] [Accepted: 10/03/2022] [Indexed: 11/17/2022]
Abstract
Over the last several years enormous progress has been made in identifying the molecular machines, including condensins and topoisomerases that fold mitotic chromosomes. The discovery that condensins generate chromatin loops through loop extrusion has revolutionized, and energized, the field of chromosome folding. To understand how these machines fold chromosomes with the appropriate dimensions, while disentangling sister chromatids, it needs to be determined how they are regulated and deployed. Here, we outline the current understanding of how these machines and factors are regulated through cell cycle dependent expression, chromatin localization, activation and inactivation through post-translational modifications, and through associations with each other, with other factors and with the chromatin template itself. There are still many open questions about how condensins and topoisomerases are regulated but given the pace of progress in the chromosome folding field, it seems likely that many of these will be answered in the years ahead.
Collapse
|
7
|
Yoshida MM, Kinoshita K, Aizawa Y, Tane S, Yamashita D, Shintomi K, Hirano T. Molecular dissection of condensin II-mediated chromosome assembly using in vitro assays. eLife 2022; 11:78984. [PMID: 35983835 PMCID: PMC9433093 DOI: 10.7554/elife.78984] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 08/11/2022] [Indexed: 11/18/2022] Open
Abstract
In vertebrates, condensin I and condensin II cooperate to assemble rod-shaped chromosomes during mitosis. Although the mechanism of action and regulation of condensin I have been studied extensively, our corresponding knowledge of condensin II remains very limited. By introducing recombinant condensin II complexes into Xenopus egg extracts, we dissect the roles of its individual subunits in chromosome assembly. We find that one of two HEAT subunits, CAP-D3, plays a crucial role in condensin II-mediated assembly of chromosome axes, whereas the other HEAT subunit, CAP-G2, has a very strong negative impact on this process. The structural maintenance of chromosomes ATPase and the basic amino acid clusters of the kleisin subunit CAP-H2 are essential for this process. Deletion of the C-terminal tail of CAP-D3 increases the ability of condensin II to assemble chromosomes and further exposes a hidden function of CAP-G2 in the lateral compaction of chromosomes. Taken together, our results uncover a multilayered regulatory mechanism unique to condensin II, and provide profound implications for the evolution of condensin II.
Collapse
Affiliation(s)
| | | | - Yuuki Aizawa
- Chromosome Dynamics Laboratory, RIKEN, Wako, Japan
| | - Shoji Tane
- Chromosome Dynamics Laboratory, RIKEN, Wako, Japan
| | | | | | | |
Collapse
|
8
|
Shintomi K. Making Mitotic Chromosomes in a Test Tube. EPIGENOMES 2022; 6:epigenomes6030020. [PMID: 35893016 PMCID: PMC9326633 DOI: 10.3390/epigenomes6030020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 07/18/2022] [Accepted: 07/18/2022] [Indexed: 02/01/2023] Open
Abstract
Mitotic chromosome assembly is an essential preparatory step for accurate transmission of the genome during cell division. During the past decades, biochemical approaches have uncovered the molecular basis of mitotic chromosomes. For example, by using cell-free assays of frog egg extracts, the condensin I complex central for the chromosome assembly process was first identified, and its functions have been intensively studied. A list of chromosome-associated proteins has been almost completed, and it is now possible to reconstitute structures resembling mitotic chromosomes with a limited number of purified factors. In this review, I introduce how far we have come in understanding the mechanism of chromosome assembly using cell-free assays and reconstitution assays, and I discuss their potential applications to solve open questions.
Collapse
Affiliation(s)
- Keishi Shintomi
- Chromosome Dynamics Laboratory, RIKEN, Wako 351-0198, Saitama, Japan
| |
Collapse
|
9
|
Haase J, Chen R, Parker WM, Bonner MK, Jenkins LM, Kelly AE. The TFIIH complex is required to establish and maintain mitotic chromosome structure. eLife 2022; 11:75475. [PMID: 35293859 PMCID: PMC8956287 DOI: 10.7554/elife.75475] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/15/2022] [Indexed: 11/13/2022] Open
Abstract
Condensins compact chromosomes to promote their equal segregation during mitosis, but the mechanism of condensin engagement with and action on chromatin is incompletely understood. Here, we show that the general transcription factor TFIIH complex is continuously required to establish and maintain a compacted chromosome structure in transcriptionally silent Xenopus egg extracts. Inhibiting the DNA-dependent ATPase activity of the TFIIH complex subunit XPB rapidly and reversibly induces a complete loss of chromosome structure and prevents the enrichment of condensins I and II, but not topoisomerase II, on chromatin. In addition, inhibiting TFIIH prevents condensation of both mouse and Xenopus nuclei in Xenopus egg extracts, which suggests an evolutionarily conserved mechanism of TFIIH action. Reducing nucleosome density through partial histone depletion restores chromosome structure and condensin enrichment in the absence of TFIIH activity. We propose that the TFIIH complex promotes mitotic chromosome condensation by dynamically altering the chromatin environment to facilitate condensin loading and condensin-dependent loop extrusion.
Collapse
Affiliation(s)
- Julian Haase
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| | - Richard Chen
- Graduate School of Biomedical Sciences, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Wesley M Parker
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| | - Mary Kate Bonner
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| | - Lisa M Jenkins
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| | - Alexander E Kelly
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| |
Collapse
|
10
|
Kinoshita K, Tsubota Y, Tane S, Aizawa Y, Sakata R, Takeuchi K, Shintomi K, Nishiyama T, Hirano T. A loop extrusion-independent mechanism contributes to condensin I-mediated chromosome shaping. J Cell Biol 2022; 221:212966. [PMID: 35045152 PMCID: PMC8932526 DOI: 10.1083/jcb.202109016] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 11/16/2021] [Accepted: 12/23/2021] [Indexed: 12/14/2022] Open
Abstract
Condensin I is a five-subunit protein complex that is central to mitotic chromosome assembly in eukaryotic cells. Despite recent progress, its molecular mechanisms of action remain to be fully elucidated. By using Xenopus egg extracts as a functional assay, we find that condensin I complexes harboring mutations in its kleisin subunit CAP-H produce chromosomes with confined axes in the presence of topoisomerase IIα (topo IIα) and highly compact structures (termed “beans”) with condensin-positive central cores in its absence. The bean phenotype depends on the SMC ATPase cycle and can be reversed by subsequent addition of topo IIα. The HEAT repeat subunit CAP-D2, but not CAP-G, is essential for the bean formation. Notably, loop extrusion activities of the mutant complexes cannot explain the chromosomal defects they exhibit in Xenopus egg extracts, implying that a loop extrusion–independent mechanism contributes to condensin I–mediated chromosome assembly and shaping. We provide evidence that condensin–condensin interactions underlie these processes.
Collapse
Affiliation(s)
| | - Yuko Tsubota
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Shoji Tane
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan
| | - Yuuki Aizawa
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan
| | - Ryota Sakata
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Kozo Takeuchi
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan
| | | | - Tomoko Nishiyama
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan
| |
Collapse
|
11
|
Higashi TL, Uhlmann F. SMC complexes: Lifting the lid on loop extrusion. Curr Opin Cell Biol 2022; 74:13-22. [PMID: 35016058 PMCID: PMC9089308 DOI: 10.1016/j.ceb.2021.12.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 01/02/2023]
Abstract
Loop extrusion has emerged as a prominent hypothesis for how SMC complexes shape chromosomes - single molecule in vitro observations have yielded fascinating images of this process. When not extruding loops, SMC complexes are known to topologically entrap one or more DNAs. Here, we review how structural insight into the SMC complex cohesin has led to a molecular framework for both activities: a Brownian ratchet motion, associated with topological DNA entry, might repeat itself to elicit loop extrusion. After contrasting alternative loop extrusion models, we explore whether topological loading or loop extrusion is more adept at explaining in vivo SMC complex function. SMC variants that experimentally separate topological loading from loop extrusion will in the future probe their respective contributions to chromosome biology.
Collapse
Affiliation(s)
- Torahiko L Higashi
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, NW1 1AT, UK; Department of Cellular Biochemistry, Kyushu University, Fukuoka, 812-8582, Japan
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, NW1 1AT, UK.
| |
Collapse
|
12
|
Tane S, Shintomi K, Kinoshita K, Tsubota Y, Yoshida MM, Nishiyama T, Hirano T. Cell cycle-specific loading of condensin I is regulated by the N-terminal tail of its kleisin subunit. eLife 2022; 11:84694. [PMID: 36511239 PMCID: PMC9797191 DOI: 10.7554/elife.84694] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
Condensin I is a pentameric protein complex that plays an essential role in mitotic chromosome assembly in eukaryotic cells. Although it has been shown that condensin I loading is mitosis specific, it remains poorly understood how the robust cell cycle regulation of condensin I is achieved. Here, we set up a panel of in vitro assays to demonstrate that cell cycle-specific loading of condensin I is regulated by the N-terminal tail (N-tail) of its kleisin subunit CAP-H. Deletion of the N-tail accelerates condensin I loading and chromosome assembly in Xenopus egg mitotic extracts. Phosphorylation-deficient and phosphorylation-mimetic mutations in the CAP-H N-tail decelerate and accelerate condensin I loading, respectively. Remarkably, deletion of the N-tail enables condensin I to assemble mitotic chromosome-like structures even in interphase extracts. Together with other extract-free functional assays in vitro, our results uncover one of the multilayered mechanisms that ensure cell cycle-specific loading of condensin I onto chromosomes.
Collapse
Affiliation(s)
- Shoji Tane
- Chromosome Dynamics Laboratory, RIKENWakoJapan
| | | | | | - Yuko Tsubota
- Division of Biological Sciences, Graduate School of Science, Nagoya UniversityNagoyaJapan
| | | | - Tomoko Nishiyama
- Division of Biological Sciences, Graduate School of Science, Nagoya UniversityNagoyaJapan
| | | |
Collapse
|
13
|
Breimann L, Morao AK, Kim J, Jimenez DS, Maryn N, Bikkasani K, Carrozza MJ, Albritton SE, Kramer M, Street LA, Cerimi K, Schumann VF, Bahry E, Preibisch S, Woehler A, Ercan S. The H4K20 demethylase DPY-21 regulates the dynamics of condensin DC binding. J Cell Sci 2021; 135:273768. [PMID: 34918745 PMCID: PMC8917352 DOI: 10.1242/jcs.258818] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 11/29/2021] [Indexed: 11/26/2022] Open
Abstract
Condensin is a multi-subunit structural maintenance of chromosomes (SMC) complex that binds to and compacts chromosomes. Here, we addressed the regulation of condensin binding dynamics using Caenorhabditis elegans condensin DC, which represses X chromosomes in hermaphrodites for dosage compensation. We established fluorescence recovery after photobleaching (FRAP) using the SMC4 homolog DPY-27 and showed that a well-characterized ATPase mutation abolishes DPY-27 binding to X chromosomes. Next, we performed FRAP in the background of several chromatin modifier mutants that cause varying degrees of X chromosome derepression. The greatest effect was in a null mutant of the H4K20me2 demethylase DPY-21, where the mobile fraction of condensin DC reduced from ∼30% to 10%. In contrast, a catalytic mutant of dpy-21 did not regulate condensin DC mobility. Hi-C sequencing data from the dpy-21 null mutant showed little change compared to wild-type data, uncoupling Hi-C-measured long-range DNA contacts from transcriptional repression of the X chromosomes. Taken together, our results indicate that DPY-21 has a non-catalytic role in regulating the dynamics of condensin DC binding, which is important for transcription repression. Summary: The histone demethylase DPY-21 has catalytic and non-catalytic roles in condensin DC-mediated X chromosome repression. The non-catalytic activity regulates dynamics of condensin DC binding to X chromosomes.
Collapse
Affiliation(s)
- Laura Breimann
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA.,Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Institute for Biology, Humboldt University of Berlin, Berlin, Germany
| | - Ana Karina Morao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Jun Kim
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - David Sebastian Jimenez
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Nina Maryn
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Krishna Bikkasani
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Michael J Carrozza
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Sarah E Albritton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Maxwell Kramer
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Lena Annika Street
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Kustrim Cerimi
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Vic-Fabienne Schumann
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ella Bahry
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Stephan Preibisch
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Andrew Woehler
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| |
Collapse
|
14
|
Davidson IF, Peters JM. Genome folding through loop extrusion by SMC complexes. Nat Rev Mol Cell Biol 2021; 22:445-464. [PMID: 33767413 DOI: 10.1038/s41580-021-00349-7] [Citation(s) in RCA: 218] [Impact Index Per Article: 72.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2021] [Indexed: 02/02/2023]
Abstract
Genomic DNA is folded into loops and topologically associating domains (TADs), which serve important structural and regulatory roles. It has been proposed that these genomic structures are formed by a loop extrusion process, which is mediated by structural maintenance of chromosomes (SMC) protein complexes. Recent single-molecule studies have shown that the SMC complexes condensin and cohesin are indeed able to extrude DNA into loops. In this Review, we discuss how the loop extrusion hypothesis can explain key features of genome architecture; cellular functions of loop extrusion, such as separation of replicated DNA molecules, facilitation of enhancer-promoter interactions and immunoglobulin gene recombination; and what is known about the mechanism of loop extrusion and its regulation, for example, by chromatin boundaries that depend on the DNA binding protein CTCF. We also discuss how the loop extrusion hypothesis has led to a paradigm shift in our understanding of both genome architecture and the functions of SMC complexes.
Collapse
Affiliation(s)
- Iain F Davidson
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Jan-Michael Peters
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria.
| |
Collapse
|
15
|
Hoencamp C, Dudchenko O, Elbatsh AMO, Brahmachari S, Raaijmakers JA, van Schaik T, Sedeño Cacciatore Á, Contessoto VG, van Heesbeen RGHP, van den Broek B, Mhaskar AN, Teunissen H, St Hilaire BG, Weisz D, Omer AD, Pham M, Colaric Z, Yang Z, Rao SSP, Mitra N, Lui C, Yao W, Khan R, Moroz LL, Kohn A, St Leger J, Mena A, Holcroft K, Gambetta MC, Lim F, Farley E, Stein N, Haddad A, Chauss D, Mutlu AS, Wang MC, Young ND, Hildebrandt E, Cheng HH, Knight CJ, Burnham TLU, Hovel KA, Beel AJ, Mattei PJ, Kornberg RD, Warren WC, Cary G, Gómez-Skarmeta JL, Hinman V, Lindblad-Toh K, Di Palma F, Maeshima K, Multani AS, Pathak S, Nel-Themaat L, Behringer RR, Kaur P, Medema RH, van Steensel B, de Wit E, Onuchic JN, Di Pierro M, Lieberman Aiden E, Rowland BD. 3D genomics across the tree of life reveals condensin II as a determinant of architecture type. Science 2021; 372:984-989. [PMID: 34045355 PMCID: PMC8172041 DOI: 10.1126/science.abe2218] [Citation(s) in RCA: 111] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 04/16/2021] [Indexed: 01/01/2023]
Abstract
We investigated genome folding across the eukaryotic tree of life. We find two types of three-dimensional (3D) genome architectures at the chromosome scale. Each type appears and disappears repeatedly during eukaryotic evolution. The type of genome architecture that an organism exhibits correlates with the absence of condensin II subunits. Moreover, condensin II depletion converts the architecture of the human genome to a state resembling that seen in organisms such as fungi or mosquitoes. In this state, centromeres cluster together at nucleoli, and heterochromatin domains merge. We propose a physical model in which lengthwise compaction of chromosomes by condensin II during mitosis determines chromosome-scale genome architecture, with effects that are retained during the subsequent interphase. This mechanism likely has been conserved since the last common ancestor of all eukaryotes.
Collapse
Affiliation(s)
- Claire Hoencamp
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Olga Dudchenko
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
| | - Ahmed M O Elbatsh
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | | | - Jonne A Raaijmakers
- Division of Cell Biology, Oncode Institute, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Tom van Schaik
- Division of Gene Regulation, Oncode Institute, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | | | - Vinícius G Contessoto
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Department of Physics, Institute of Biosciences, Letters and Exact Sciences, São Paulo State University (UNESP), São José do Rio Preto - SP, 15054-000, Brazil
| | - Roy G H P van Heesbeen
- Division of Cell Biology, Oncode Institute, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Bram van den Broek
- BioImaging Facility, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Aditya N Mhaskar
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Hans Teunissen
- Division of Gene Regulation, Oncode Institute, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Brian Glenn St Hilaire
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - David Weisz
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Arina D Omer
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - Melanie Pham
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zane Colaric
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhenzhen Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech, Pudong 201210, China
| | - Suhas S P Rao
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Namita Mitra
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Christopher Lui
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - Weijie Yao
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ruqayya Khan
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Leonid L Moroz
- Whitney Laboratory and Department of Neuroscience, University of Florida, Gainesville, FL 32611, USA
| | - Andrea Kohn
- Whitney Laboratory and Department of Neuroscience, University of Florida, Gainesville, FL 32611, USA
| | - Judy St Leger
- Department of Biosciences, Cornell University College of Veterinary Medicine, Ithaca, NY 14853, USA
| | | | | | | | - Fabian Lim
- Department of Medicine and Molecular Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Emma Farley
- Department of Medicine and Molecular Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Nils Stein
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK Gatersleben), 06466 Seeland, Germany
- Center of Integrated Breeding Research (CiBreed), Department of Crop Sciences, Georg-August-University Göttingen, 37075 Göttingen, Germany
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA 6009, Australia
| | - Alexander Haddad
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - Daniel Chauss
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ayse Sena Mutlu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Meng C Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Neil D Young
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, VIC 3010, Australia
| | - Evin Hildebrandt
- Avian Diseases and Oncology Laboratory, US Department of Agriculture, Agricultural Research Service, East Lansing, MI 48823, USA
| | - Hans H Cheng
- Avian Diseases and Oncology Laboratory, US Department of Agriculture, Agricultural Research Service, East Lansing, MI 48823, USA
| | | | - Theresa L U Burnham
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, CA 95616, USA
- Coastal and Marine Institute and Department of Biology, San Diego State University, San Diego, CA 92106, USA
| | - Kevin A Hovel
- Coastal and Marine Institute and Department of Biology, San Diego State University, San Diego, CA 92106, USA
| | - Andrew J Beel
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Pierre-Jean Mattei
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Roger D Kornberg
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Wesley C Warren
- Department of Animal Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Gregory Cary
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - José Luis Gómez-Skarmeta
- Centro Andaluz de Biología del Desarrollo CSIC, Universidad Pablo de Olavide, 41013 Sevilla, Spain
| | - Veronica Hinman
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Kerstin Lindblad-Toh
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, 751 23 Uppsala, Sweden
| | - Federica Di Palma
- Department of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Kazuhiro Maeshima
- Genome Dynamics Laboratory, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, Sokendai (Graduate University for Advanced Studies), Mishima, Shizuoka 411-8540, Japan
| | - Asha S Multani
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sen Pathak
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Liesl Nel-Themaat
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Richard R Behringer
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Parwinder Kaur
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA 6009, Australia
| | - René H Medema
- Division of Cell Biology, Oncode Institute, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Bas van Steensel
- Division of Gene Regulation, Oncode Institute, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Elzo de Wit
- Division of Gene Regulation, Oncode Institute, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - José N Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Departments of Physics and Astronomy, Chemistry, and Biosciences, Rice University, Houston, TX 77005, USA
| | - Michele Di Pierro
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Erez Lieberman Aiden
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech, Pudong 201210, China
- UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA 6009, Australia
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Benjamin D Rowland
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands.
| |
Collapse
|
16
|
Gerguri T, Fu X, Kakui Y, Khatri BS, Barrington C, Bates PA, Uhlmann F. Comparison of loop extrusion and diffusion capture as mitotic chromosome formation pathways in fission yeast. Nucleic Acids Res 2021; 49:1294-1312. [PMID: 33434270 PMCID: PMC7897502 DOI: 10.1093/nar/gkaa1270] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 12/01/2020] [Accepted: 12/21/2020] [Indexed: 01/17/2023] Open
Abstract
Underlying higher order chromatin organization are Structural Maintenance of Chromosomes (SMC) complexes, large protein rings that entrap DNA. The molecular mechanism by which SMC complexes organize chromatin is as yet incompletely understood. Two prominent models posit that SMC complexes actively extrude DNA loops (loop extrusion), or that they sequentially entrap two DNAs that come into proximity by Brownian motion (diffusion capture). To explore the implications of these two mechanisms, we perform biophysical simulations of a 3.76 Mb-long chromatin chain, the size of the long Schizosaccharomyces pombe chromosome I left arm. On it, the SMC complex condensin is modeled to perform loop extrusion or diffusion capture. We then compare computational to experimental observations of mitotic chromosome formation. Both loop extrusion and diffusion capture can result in native-like contact probability distributions. In addition, the diffusion capture model more readily recapitulates mitotic chromosome axis shortening and chromatin compaction. Diffusion capture can also explain why mitotic chromatin shows reduced, as well as more anisotropic, movements, features that lack support from loop extrusion. The condensin distribution within mitotic chromosomes, visualized by stochastic optical reconstruction microscopy (STORM), shows clustering predicted from diffusion capture. Our results inform the evaluation of current models of mitotic chromosome formation.
Collapse
Affiliation(s)
- Tereza Gerguri
- Biomolecular Modelling Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Xiao Fu
- Biomolecular Modelling Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Yasutaka Kakui
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
- Waseda Institute for Advanced Study, Waseda University, 1-21-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051, Japan
| | - Bhavin S Khatri
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
| | - Christopher Barrington
- Bioinformatics and Biostatistics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Paul A Bates
- Biomolecular Modelling Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| |
Collapse
|
17
|
Birnie A, Dekker C. Genome-in-a-Box: Building a Chromosome from the Bottom Up. ACS NANO 2021; 15:111-124. [PMID: 33347266 PMCID: PMC7844827 DOI: 10.1021/acsnano.0c07397] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 12/16/2020] [Indexed: 05/24/2023]
Abstract
Chromosome structure and dynamics are essential for life, as the way that our genomes are spatially organized within cells is crucial for gene expression, differentiation, and genome transfer to daughter cells. There is a wide variety of methods available to study chromosomes, ranging from live-cell studies to single-molecule biophysics, which we briefly review. While these technologies have yielded a wealth of data, such studies still leave a significant gap between top-down experiments on live cells and bottom-up in vitro single-molecule studies of DNA-protein interactions. Here, we introduce "genome-in-a-box" (GenBox) as an alternative in vitro approach to build and study chromosomes, which bridges this gap. The concept is to assemble a chromosome from the bottom up by taking deproteinated genome-sized DNA isolated from live cells and subsequently add purified DNA-organizing elements, followed by encapsulation in cell-sized containers using microfluidics. Grounded in the rationale of synthetic cell research, the approach would enable to experimentally study emergent effects at the global genome level that arise from the collective action of local DNA-structuring elements. We review the various DNA-structuring elements present in nature, from nucleoid-associated proteins and SMC complexes to phase separation and macromolecular crowders. Finally, we discuss how GenBox can contribute to several open questions on chromosome structure and dynamics.
Collapse
Affiliation(s)
- Anthony Birnie
- Department of Bionanoscience, Kavli
Institute of Nanoscience Delft, Delft University
of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli
Institute of Nanoscience Delft, Delft University
of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| |
Collapse
|
18
|
Cutts EE, Vannini A. Condensin complexes: understanding loop extrusion one conformational change at a time. Biochem Soc Trans 2020; 48:2089-2100. [PMID: 33005926 PMCID: PMC7609036 DOI: 10.1042/bst20200241] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/07/2020] [Accepted: 09/09/2020] [Indexed: 12/12/2022]
Abstract
Condensin and cohesin, both members of the structural maintenance of chromosome (SMC) family, contribute to the regulation and structure of chromatin. Recent work has shown both condensin and cohesin extrude DNA loops and most likely work via a conserved mechanism. This review focuses on condensin complexes, highlighting recent in vitro work characterising DNA loop formation and protein structure. We discuss similarities between condensin and cohesin complexes to derive a possible mechanistic model, as well as discuss differences that exist between the different condensin isoforms found in higher eukaryotes.
Collapse
Affiliation(s)
- Erin E. Cutts
- Division of Structural Biology, The Institute of Cancer Research, London SW7 3RP, U.K
| | - Alessandro Vannini
- Division of Structural Biology, The Institute of Cancer Research, London SW7 3RP, U.K
- Fondazione Human Technopole, Structural Biology Research Centre, 20157 Milan, Italy
| |
Collapse
|
19
|
Hassler M, Shaltiel IA, Kschonsak M, Simon B, Merkel F, Thärichen L, Bailey HJ, Macošek J, Bravo S, Metz J, Hennig J, Haering CH. Structural Basis of an Asymmetric Condensin ATPase Cycle. Mol Cell 2020; 74:1175-1188.e9. [PMID: 31226277 PMCID: PMC6591010 DOI: 10.1016/j.molcel.2019.03.037] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 03/16/2019] [Accepted: 03/27/2019] [Indexed: 01/20/2023]
Abstract
The condensin protein complex plays a key role in the structural organization of genomes. How the ATPase activity of its SMC subunits drives large-scale changes in chromosome topology has remained unknown. Here we reconstruct, at near-atomic resolution, the sequence of events that take place during the condensin ATPase cycle. We show that ATP binding induces a conformational switch in the Smc4 head domain that releases its hitherto undescribed interaction with the Ycs4 HEAT-repeat subunit and promotes its engagement with the Smc2 head into an asymmetric heterodimer. SMC head dimerization subsequently enables nucleotide binding at the second active site and disengages the Brn1 kleisin subunit from the Smc2 coiled coil to open the condensin ring. These large-scale transitions in the condensin architecture lay out a mechanistic path for its ability to extrude DNA helices into large loop structures.
Collapse
Affiliation(s)
- Markus Hassler
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Indra A Shaltiel
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Marc Kschonsak
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Bernd Simon
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Fabian Merkel
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; Collaboration for Joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Lena Thärichen
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Henry J Bailey
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Jakub Macošek
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Sol Bravo
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Jutta Metz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Janosch Hennig
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Christian H Haering
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
| |
Collapse
|
20
|
Elbatsh AMO, Kim E, Eeftens JM, Raaijmakers JA, van der Weide RH, García-Nieto A, Bravo S, Ganji M, Uit de Bos J, Teunissen H, Medema RH, de Wit E, Haering CH, Dekker C, Rowland BD. Distinct Roles for Condensin's Two ATPase Sites in Chromosome Condensation. Mol Cell 2019; 76:724-737.e5. [PMID: 31629658 PMCID: PMC6900782 DOI: 10.1016/j.molcel.2019.09.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/17/2019] [Accepted: 09/13/2019] [Indexed: 01/19/2023]
Abstract
Condensin is a conserved SMC complex that uses its ATPase machinery to structure genomes, but how it does so is largely unknown. We show that condensin's ATPase has a dual role in chromosome condensation. Mutation of one ATPase site impairs condensation, while mutating the second site results in hyperactive condensin that compacts DNA faster than wild-type, both in vivo and in vitro. Whereas one site drives loop formation, the second site is involved in the formation of more stable higher-order Z loop structures. Using hyperactive condensin I, we reveal that condensin II is not intrinsically needed for the shortening of mitotic chromosomes. Condensin II rather is required for a straight chromosomal axis and enables faithful chromosome segregation by counteracting the formation of ultrafine DNA bridges. SMC complexes with distinct roles for each ATPase site likely reflect a universal principle that enables these molecular machines to intricately control chromosome architecture.
Collapse
Affiliation(s)
- Ahmed M O Elbatsh
- Division of Gene Regulation, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Eugene Kim
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands
| | - Jorine M Eeftens
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands
| | - Jonne A Raaijmakers
- Division of Cell Biology, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Robin H van der Weide
- Division of Gene Regulation, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Alberto García-Nieto
- Division of Gene Regulation, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Sol Bravo
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Mahipal Ganji
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands
| | - Jelmi Uit de Bos
- Division of Cell Biology, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Hans Teunissen
- Division of Gene Regulation, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - René H Medema
- Division of Cell Biology, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Elzo de Wit
- Division of Gene Regulation, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Christian H Haering
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands.
| | - Benjamin D Rowland
- Division of Gene Regulation, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands.
| |
Collapse
|
21
|
Thadani R, Kamenz J, Heeger S, Muñoz S, Uhlmann F. Cell-Cycle Regulation of Dynamic Chromosome Association of the Condensin Complex. Cell Rep 2019; 23:2308-2317. [PMID: 29791843 PMCID: PMC5986713 DOI: 10.1016/j.celrep.2018.04.082] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 12/15/2017] [Accepted: 04/18/2018] [Indexed: 11/16/2022] Open
Abstract
Eukaryotic cells inherit their genomes in the form of chromosomes, which are formed from the compaction of interphase chromatin by the condensin complex. Condensin is a member of the structural maintenance of chromosomes (SMC) family of ATPases, large ring-shaped protein assemblies that entrap DNA to establish chromosomal interactions. Here, we use the budding yeast Saccharomyces cerevisiae to dissect the role of the condensin ATPase and its relationship with cell-cycle-regulated chromosome binding dynamics. ATP hydrolysis-deficient condensin binds to chromosomes but is defective in chromosome condensation and segregation. By modulating the ATPase, we demonstrate that it controls condensin's dynamic turnover on chromosomes. Mitosis-specific phosphorylation of condensin's Smc4 subunit reduces the turnover rate. However, reducing turnover by itself is insufficient to compact chromosomes. We propose that condensation requires fine-tuned dynamic condensin interactions with more than one DNA. These results enhance our molecular understanding of condensin function during chromosome condensation.
Collapse
Affiliation(s)
- Rahul Thadani
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK; Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Julia Kamenz
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Sebastian Heeger
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Sofía Muñoz
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
| |
Collapse
|
22
|
Molecular Dynamics Simulations of Condensin-Mediated Mitotic Chromosome Assembly. Methods Mol Biol 2019. [PMID: 31147926 DOI: 10.1007/978-1-4939-9520-2_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Molecular dynamics simulation is a powerful tool used in modern molecular modeling, which enables a deeper comprehension of the physical behavior of atoms and molecules at a micro level. In this study, we simulated mitotic chromosome assembly mediated by condensins, a class of large protein complexes containing a pair of structural maintenance of chromosomes (SMC) subunits that are central to this process. In this chapter, we present the construction of a coarse-grained physical model of chromosomal DNA fibers and condensin molecules, and monitoring of the function of condensins in mitotic chromosome assembly, using computer-based molecular dynamics simulation. We explain how our model of chromosomes and condensins may be simulated using a package of molecular dynamics simulation. Procedures involved in calculating the observables of dynamics are described, together with an example of the simulation results.
Collapse
|
23
|
Hara K, Kinoshita K, Migita T, Murakami K, Shimizu K, Takeuchi K, Hirano T, Hashimoto H. Structural basis of HEAT-kleisin interactions in the human condensin I subcomplex. EMBO Rep 2019; 20:embr.201847183. [PMID: 30858338 PMCID: PMC6501013 DOI: 10.15252/embr.201847183] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 02/13/2019] [Accepted: 02/20/2019] [Indexed: 12/30/2022] Open
Abstract
Condensin I is a multi‐protein complex that plays an essential role in mitotic chromosome assembly and segregation in eukaryotes. It is composed of five subunits: two SMC (SMC2 and SMC4), a kleisin (CAP‐H), and two HEAT‐repeat (CAP‐D2 and CAP‐G) subunits. Although balancing acts of the two HEAT‐repeat subunits have been demonstrated to enable this complex to support the dynamic assembly of chromosomal axes in vertebrate cells, its underlying mechanisms remain poorly understood. Here, we report the crystal structure of a human condensin I subcomplex comprising hCAP‐G and hCAP‐H. hCAP‐H binds to the concave surfaces of a harp‐shaped HEAT‐repeat domain of hCAP‐G. Physical interaction between hCAP‐G and hCAP‐H is indeed essential for mitotic chromosome assembly recapitulated in Xenopus egg cell‐free extracts. Furthermore, this study reveals that the human CAP‐G‐H subcomplex has the ability to interact with not only double‐stranded DNA, but also single‐stranded DNA, suggesting functional divergence of the vertebrate condensin I complex in proper mitotic chromosome assembly.
Collapse
Affiliation(s)
- Kodai Hara
- Department of Physical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | | | - Tomoko Migita
- Department of Physical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Kei Murakami
- Department of Physical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Kenichiro Shimizu
- Department of Physical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Kozo Takeuchi
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan
| | - Hiroshi Hashimoto
- Department of Physical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| |
Collapse
|
24
|
Cdc48/VCP Promotes Chromosome Morphogenesis by Releasing Condensin from Self-Entrapment in Chromatin. Mol Cell 2019; 69:664-676.e5. [PMID: 29452641 DOI: 10.1016/j.molcel.2018.01.030] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 11/04/2017] [Accepted: 01/22/2018] [Indexed: 01/26/2023]
Abstract
The morphological transformation of amorphous chromatin into distinct chromosomes is a hallmark of mitosis. To achieve this, chromatin must be compacted and remodeled by a ring-shaped enzyme complex known as condensin. However, the mechanistic basis underpinning condensin's role in chromosome remodeling has remained elusive. Here we show that condensin has a strong tendency to trap itself in its own reaction product during chromatin compaction and yet is capable of interacting with chromatin in a highly dynamic manner in vivo. To resolve this apparent paradox, we identified specific chromatin remodelers and AAA-class ATPases that act in a coordinated manner to release condensin from chromatin entrapment. The Cdc48 segregase is the central linchpin of this regulatory mechanism and promotes ubiquitin-dependent cycling of condensin on mitotic chromatin as well as effective chromosome condensation. Collectively, our results show that condensin inhibition by its own reaction product is relieved by forceful enzyme extraction from chromatin.
Collapse
|
25
|
Baxter J, Oliver AW, Schalbetter SA. Are SMC Complexes Loop Extruding Factors? Linking Theory With Fact. Bioessays 2018; 41:e1800182. [PMID: 30506702 DOI: 10.1002/bies.201800182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/05/2018] [Indexed: 01/24/2023]
Abstract
The extreme length of chromosomal DNA requires organizing mechanisms to both promote functional genetic interactions and ensure faithful chromosome segregation when cells divide. Microscopy and genome-wide contact frequency analyses indicate that intra-chromosomal looping of DNA is a primary pathway of chromosomal organization during all stages of the cell cycle. DNA loop extrusion has emerged as a unifying model for how chromosome loops are formed in cis in different genomic contexts and cell cycle stages. The highly conserved family of SMC complexes have been found to be required for DNA cis-looping and have been suggested to be the enzymatic core of loop extruding machines. Here, the current body of evidence available for the in vivo and in vitro action of SMC complexes is discussed and compared to the predictions made by the loop extrusion model. How SMC complexes may differentially act on chromatin to generate DNA loops and how they could work to generate the dynamic and functionally appropriate organization of DNA in cells is explored.
Collapse
Affiliation(s)
- Jonathan Baxter
- Genome Damage and Stability Centre, Science Park Road, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, UK
| | - Antony W Oliver
- Genome Damage and Stability Centre, Science Park Road, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, UK
| | - Stephanie A Schalbetter
- Genome Damage and Stability Centre, Science Park Road, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, UK
| |
Collapse
|
26
|
Lawrimore J, Doshi A, Friedman B, Yeh E, Bloom K. Geometric partitioning of cohesin and condensin is a consequence of chromatin loops. Mol Biol Cell 2018; 29:2737-2750. [PMID: 30207827 PMCID: PMC6249845 DOI: 10.1091/mbc.e18-02-0131] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 08/13/2018] [Accepted: 09/04/2018] [Indexed: 12/29/2022] Open
Abstract
SMC (structural maintenance of chromosomes) complexes condensin and cohesin are crucial for proper chromosome organization. Condensin has been reported to be a mechanochemical motor capable of forming chromatin loops, while cohesin passively diffuses along chromatin to tether sister chromatids. In budding yeast, the pericentric region is enriched in both condensin and cohesin. As in higher-eukaryotic chromosomes, condensin is localized to the axial chromatin of the pericentric region, while cohesin is enriched in the radial chromatin. Thus, the pericentric region serves as an ideal model for deducing the role of SMC complexes in chromosome organization. We find condensin-mediated chromatin loops establish a robust chromatin organization, while cohesin limits the area that chromatin loops can explore. Upon biorientation, extensional force from the mitotic spindle aggregates condensin-bound chromatin from its equilibrium position to the axial core of pericentric chromatin, resulting in amplified axial tension. The axial localization of condensin depends on condensin's ability to bind to chromatin to form loops, while the radial localization of cohesin depends on cohesin's ability to diffuse along chromatin. The different chromatin-tethering modalities of condensin and cohesin result in their geometric partitioning in the presence of an extensional force on chromatin.
Collapse
Affiliation(s)
- Josh Lawrimore
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Ayush Doshi
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Brandon Friedman
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Elaine Yeh
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kerry Bloom
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| |
Collapse
|
27
|
Condensin ATPase motifs contribute differentially to the maintenance of chromosome morphology and genome stability. PLoS Biol 2018; 16:e2003980. [PMID: 29949571 PMCID: PMC6039025 DOI: 10.1371/journal.pbio.2003980] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 07/10/2018] [Accepted: 06/12/2018] [Indexed: 02/06/2023] Open
Abstract
Effective transfer of genetic information during cell division requires a major reorganization of chromosome structure. This process is triggered by condensin, a conserved pentameric ATPase essential for chromosome condensation. How condensin harnesses the energy of ATP hydrolysis to promote chromatin reorganization is unknown. To address this issue, we performed a genetic screen specifically focused on the ATPase domain of Smc4, a core subunit of condensin. Our screen identified mutational hotspots that impair condensin’s ability to condense chromosomes to various degrees. These mutations have distinct effects on viability, genome stability, and chromosome morphology, revealing unique thresholds for condensin enzymatic activity in the execution of its cellular functions. Biochemical analyses indicate that inactivation of Smc4 ATPase activity can result in cell lethality because it favors a specific configuration of condensin that locks ATP in the enzyme. Together, our results provide critical insights into the mechanism used by condensin to harness the energy of ATP hydrolysis for the compaction of chromatin. In eukaryotes, the deletion of a single copy of most genes shows little or no detectable phenotype under standard proliferative conditions. This implies that a large reduction in the level of a gene product can be tolerated by eukaryotic organisms and that a “reserve capacity” is built in the protein machinery that drives most cellular processes. Here, we test if the main effector of chromosome condensation—the condensin complex—operates with a reserve enzymatic capacity in the execution of its multiple functions in vivo. To achieve this, we created an allelic series of mutations that selectively inactivate condensin ATPase activity in a graded manner. We show that many core functions of condensin can be maintained even at low levels of ATPase activity. Our data also reveal the existence of various thresholds of ATPase activity that are necessary and sufficient for the execution of different cellular functions by condensin. Notably, loss of genome stability at repetitive DNA is only observed when condensin ATPase activity is severely impaired. Taken together, our results reveal key insights into the process of ATP hydrolysis by condensin and how the energy it releases promotes genome remodeling and stability during cell division.
Collapse
|
28
|
Sakai Y, Mochizuki A, Kinoshita K, Hirano T, Tachikawa M. Modeling the functions of condensin in chromosome shaping and segregation. PLoS Comput Biol 2018; 14:e1006152. [PMID: 29912867 PMCID: PMC6005465 DOI: 10.1371/journal.pcbi.1006152] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 04/24/2018] [Indexed: 11/18/2022] Open
Abstract
The mechanistic details underlying the assembly of rod-shaped chromosomes during mitosis and how they segregate from each other to act as individually mobile units remain largely unknown. Here, we construct a coarse-grained physical model of chromosomal DNA and condensins, a class of large protein complexes that plays key roles in these processes. We assume that condensins have two molecular activities: consecutive loop formation in DNA and inter-condensin attractions. Our simulation demonstrates that both of these activities and their balancing acts are essential for the efficient shaping and segregation of mitotic chromosomes. Our results also demonstrate that the shaping and segregation processes are strongly correlated, implying their mechanistic coupling during mitotic chromosome assembly. Our results highlight the functional importance of inter-condensin attractions in chromosome shaping and segregation. Immediately before a cell divides, chromosomal DNA in a eukaryotic cell is packaged into a discrete set of rod-shaped chromosomes. This process, known as mitotic chromosome assembly or condensation, secures the faithful segregation of genetic information into daughter cells. Central to this mechanistically complex process is a class of protein complexes known as condensins. However, how condensins support the assembly and segregation of mitotic chromosomes at a mechanistic level remains elusive. Here we construct a coarse-grained physical model of chromosomal DNA fibers and condensin molecules, and study how condensins work in the mitotic chromosome assembly using computer simulations. Our results show that two activities of condensins, formation of consecutive loops in chromosomal DNA fibers and inter-condensin attractions, are necessary for both the shaping and segregation of mitotic chromosomes, and balancing acts of these activities help to coordinate the efficient progress of the processes. Importantly, chromosome shaping and segregation in our results are strongly correlated, implying that they are controlled by the same underlying mechanism mediated by condensins.
Collapse
Affiliation(s)
- Yuji Sakai
- iTHES Research Group, RIKEN, Wako, Japan.,Theoretical Biology Laboratory, RIKEN, Wako, Japan.,Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Atsushi Mochizuki
- iTHES Research Group, RIKEN, Wako, Japan.,Theoretical Biology Laboratory, RIKEN, Wako, Japan.,iTHEMS Program, RIKEN, Wako, Japan.,CREST, JST 4-1-8 Honcho, Kawaguchi, Japan
| | | | | | - Masashi Tachikawa
- iTHES Research Group, RIKEN, Wako, Japan.,Theoretical Biology Laboratory, RIKEN, Wako, Japan.,iTHEMS Program, RIKEN, Wako, Japan
| |
Collapse
|
29
|
Abstract
The mitotic chromosome, which is composed of a pair of sister chromatids, is a large macromolecular assembly that ensures faithful transmission of genetic information into daughter cells. Despite its fundamental importance, how a nucleosome fiber is folded and assembled into a large-scale chromatid structure remains poorly understood. To address this question, we have established a biochemically tractable system in which mitotic chromatids can be reconstituted in vitro by mixing a simple substrate (sperm nucleus) and a limited number of purified factors. The minimum set of required factors includes core histones, three histone chaperones, topoisomerase II, and condensin I. In this article, we describe a set of protocols for the preparation of key reagents and the setup of reconstitution reactions. We believe that this classical approach of biochemical reconstitution will be of great help to dissect the mechanisms of action of individual factors during mitotic chromatid assembly and to assess the contribution of nucleosome dynamics to this process from a fresh angle. © 2018 by John Wiley & Sons, Inc.
Collapse
|
30
|
Wang HZ, Yang SH, Li GY, Cao X. Subunits of human condensins are potential therapeutic targets for cancers. Cell Div 2018; 13:2. [PMID: 29467813 PMCID: PMC5819170 DOI: 10.1186/s13008-018-0035-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 02/05/2018] [Indexed: 11/16/2022] Open
Abstract
The main role of condensins is to regulate chromosome condensation and segregation during cell cycles. Recently, it has been suggested in the literatures that subunits of condensin I and condensin II are involved in some human cancers. This paper will first briefly discuss discoveries of human condensins, their components and structures, and their multiple cellular functions. This will be followed by reviews of most recent studies on subunits of human condensins and their dysregulations or mutations in human cancers. It can be concluded that many of these subunits have potentials to be novel targets for cancer therapies. However, hCAP-D2, a subunit of human condensin I, has not been directly documented to be associated with any human cancers to date. This review hypothesizes that hCAP-D2 can also be a potential therapeutic target for human cancers, and therefore that all subunits of human condensins are potential therapeutic targets for human cancers.
Collapse
Affiliation(s)
- Hong-Zhen Wang
- 1School of Life Sciences, Jilin Normal University, Siping, 136000 P. R. China.,2Key Laboratory for Molecular Enzymology and Engineering of The Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012 P. R. China.,3Department of Chemical and Biological Engineering, University of Ottawa, Ottawa, K1N 6N5 Canada
| | - Si-Han Yang
- 1School of Life Sciences, Jilin Normal University, Siping, 136000 P. R. China
| | - Gui-Ying Li
- 2Key Laboratory for Molecular Enzymology and Engineering of The Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012 P. R. China
| | - Xudong Cao
- 3Department of Chemical and Biological Engineering, University of Ottawa, Ottawa, K1N 6N5 Canada
| |
Collapse
|
31
|
Eeftens JM, Bisht S, Kerssemakers J, Kschonsak M, Haering CH, Dekker C. Real-time detection of condensin-driven DNA compaction reveals a multistep binding mechanism. EMBO J 2017; 36:3448-3457. [PMID: 29118001 PMCID: PMC5709735 DOI: 10.15252/embj.201797596] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/18/2017] [Accepted: 10/19/2017] [Indexed: 11/09/2022] Open
Abstract
Condensin, a conserved member of the SMC protein family of ring-shaped multi-subunit protein complexes, is essential for structuring and compacting chromosomes. Despite its key role, its molecular mechanism has remained largely unknown. Here, we employ single-molecule magnetic tweezers to measure, in real time, the compaction of individual DNA molecules by the budding yeast condensin complex. We show that compaction can proceed in large steps, driving DNA molecules into a fully condensed state against forces of up to 2 pN. Compaction can be reversed by applying high forces or adding buffer of high ionic strength. While condensin can stably bind DNA in the absence of ATP, ATP hydrolysis by the SMC subunits is required for rendering the association salt insensitive and for the subsequent compaction process. Our results indicate that the condensin reaction cycle involves two distinct steps, where condensin first binds DNA through electrostatic interactions before using ATP hydrolysis to encircle the DNA topologically within its ring structure, which initiates DNA compaction. The finding that both binding modes are essential for its DNA compaction activity has important implications for understanding the mechanism of chromosome compaction.
Collapse
Affiliation(s)
- Jorine M Eeftens
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands
| | - Shveta Bisht
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Jacob Kerssemakers
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands
| | - Marc Kschonsak
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Christian H Haering
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands
| |
Collapse
|
32
|
Shintomi K, Hirano T. Mitotic Chromosome Assembly In Vitro: Functional Cross Talk between Nucleosomes and Condensins. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2017; 82:157-164. [PMID: 29118204 DOI: 10.1101/sqb.2017.82.033639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The mitotic chromosome is a macromolecular assembly that ensures error-free transmission of the genome during cell division. It has long been a big mystery how long stretches of DNA might be folded into rod-shaped chromosomes or how such an elaborate process might be accomplished at a mechanistic level. Cell-free extracts made from frog eggs offer a unique opportunity to address these questions by enabling mitotic chromosomes to be assembled in a test tube. Moreover, the core part of the chromosome assembly reaction can now be reconstituted with a limited number of purified factors. A combination of these in vitro assays makes it possible not only to prepare a complete list of proteins required for chromosome assembly but also to dissect functions of individual proteins and their cooperation with unparalleled clarity. Emerging lines of evidence underscore the paramount importance of condensins in building mitotic chromosomes and shed new light on the functional cross talk between nucleosomes and condensins in this process.
Collapse
Affiliation(s)
- Keishi Shintomi
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| |
Collapse
|
33
|
Oligomerization and ATP stimulate condensin-mediated DNA compaction. Sci Rep 2017; 7:14279. [PMID: 29079757 PMCID: PMC5660149 DOI: 10.1038/s41598-017-14701-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 10/16/2017] [Indexed: 11/09/2022] Open
Abstract
Large-scale chromatin remodeling during mitosis is catalyzed by a heteropentameric enzyme known as condensin. The DNA-organizing mechanism of condensin depends on the energy of ATP hydrolysis but how this activity specifically promotes proper compaction and segregation of chromosomes during mitosis remains poorly understood. Purification of budding yeast condensin reveals that it occurs not only in the classical heteropentameric "monomer" form, but that it also adopts much larger configurations consistent with oligomerization. We use a single-DNA magnetic tweezers assay to study compaction of DNA by yeast condensin, with the result that only the multimer shows ATP-enhanced DNA-compaction. The compaction reaction involves step-like events of 200 nm (600 bp) size and is strongly suppressed by forces above 1 pN, consistent with a loop-capture mechanism for initial binding and compaction. The compaction reactions are largely insensitive to DNA torsional stress. Our results suggest a physiological role for oligomerized condensin in driving gradual chromatin compaction by step-like and slow "creeping" dynamics consistent with a loop-extrusion mechanism.
Collapse
|
34
|
Kschonsak M, Merkel F, Bisht S, Metz J, Rybin V, Hassler M, Haering CH. Structural Basis for a Safety-Belt Mechanism That Anchors Condensin to Chromosomes. Cell 2017; 171:588-600.e24. [PMID: 28988770 PMCID: PMC5651216 DOI: 10.1016/j.cell.2017.09.008] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 06/07/2017] [Accepted: 09/05/2017] [Indexed: 12/13/2022]
Abstract
Condensin protein complexes coordinate the formation of mitotic chromosomes and thereby ensure the successful segregation of replicated genomes. Insights into how condensin complexes bind to chromosomes and alter their topology are essential for understanding the molecular principles behind the large-scale chromatin rearrangements that take place during cell divisions. Here, we identify a direct DNA-binding site in the eukaryotic condensin complex, which is formed by its Ycg1Cnd3 HEAT-repeat and Brn1Cnd2 kleisin subunits. DNA co-crystal structures reveal a conserved, positively charged groove that accommodates the DNA double helix. A peptide loop of the kleisin subunit encircles the bound DNA and, like a safety belt, prevents its dissociation. Firm closure of the kleisin loop around DNA is essential for the association of condensin complexes with chromosomes and their DNA-stimulated ATPase activity. Our data suggest a sophisticated molecular basis for anchoring condensin complexes to chromosomes that enables the formation of large-sized chromatin loops.
Collapse
Affiliation(s)
- Marc Kschonsak
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Fabian Merkel
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Shveta Bisht
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Jutta Metz
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Vladimir Rybin
- Protein Expression and Purification Core Facility, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Markus Hassler
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany.
| | - Christian H Haering
- Cell Biology and Biophysics Unit, Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany.
| |
Collapse
|
35
|
Ono T, Sakamoto C, Nakao M, Saitoh N, Hirano T. Condensin II plays an essential role in reversible assembly of mitotic chromosomes in situ. Mol Biol Cell 2017; 28:2875-2886. [PMID: 28835373 PMCID: PMC5638589 DOI: 10.1091/mbc.e17-04-0252] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 01/31/2023] Open
Abstract
A modified protocol for inducing reversible assembly of mitotic chromosomes in situ is developed. As judged by this assay, which is combined with quantitative morphological analyses using a supervised machine-learning algorithm, condensin II plays a crucial role in both the recovery of chromatin shapes and the reorganization of chromosome axes. Condensins I and II are multisubunit complexes that play a central role in mitotic chromosome assembly. Although both complexes become concentrated along the axial region of each chromatid by metaphase, it remains unclear exactly how such axes might assemble and contribute to chromosome shaping. To address these questions from a physico-chemical point of view, we have established a set of two-step protocols for inducing reversible assembly of chromosome structure in situ, namely within a whole cell. In this assay, mitotic chromosomes are first expanded in a hypotonic buffer containing a Mg2+-chelating agent and then converted into different shapes in a NaCl concentration-dependent manner. Both chromatin and condensin-positive chromosome axes are converted into near-original shapes at 100 mM NaCl. This assay combined with small interfering RNA depletion demonstrates that the recovery of chromatin shapes and the reorganization of axes are highly sensitive to depletion of condensin II but less sensitive to depletion of condensin I or topoisomerase IIα. Furthermore, quantitative morphological analyses using the machine-learning algorithm wndchrm support the notion that chromosome shaping is tightly coupled to the reorganization of condensin II-based axes. We propose that condensin II makes a primary contribution to mitotic chromosome architecture and maintenance in human cells.
Collapse
Affiliation(s)
- Takao Ono
- Chromosome Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Chiyomi Sakamoto
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811, Japan
| | - Mitsuyoshi Nakao
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811, Japan
| | - Noriko Saitoh
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| |
Collapse
|
36
|
An SMC-like protein binds and regulates Caenorhabditis elegans condensins. PLoS Genet 2017; 13:e1006614. [PMID: 28301465 PMCID: PMC5373644 DOI: 10.1371/journal.pgen.1006614] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 03/30/2017] [Accepted: 02/01/2017] [Indexed: 01/17/2023] Open
Abstract
Structural Maintenance of Chromosomes (SMC) family proteins participate in multisubunit complexes that govern chromosome structure and dynamics. SMC-containing condensin complexes create chromosome topologies essential for mitosis/meiosis, gene expression, recombination, and repair. Many eukaryotes have two condensin complexes (I and II); C. elegans has three (I, II, and the X-chromosome specialized condensin IDC) and their regulation is poorly understood. Here we identify a novel SMC-like protein, SMCL-1, that binds to C. elegans condensin SMC subunits, and modulates condensin functions. Consistent with a possible role as a negative regulator, loss of SMCL-1 partially rescued the lethal and sterile phenotypes of a hypomorphic condensin mutant, while over-expression of SMCL-1 caused lethality, chromosome mis-segregation, and disruption of condensin IDC localization on X chromosomes. Unlike canonical SMC proteins, SMCL-1 lacks hinge and coil domains, and its ATPase domain lacks conserved amino acids required for ATP hydrolysis, leading to the speculation that it may inhibit condensin ATPase activity. SMCL-1 homologs are apparent only in the subset of Caenorhabditis species in which the condensin I and II subunit SMC-4 duplicated to create the condensin IDC- specific subunit DPY-27, suggesting that SMCL-1 helps this lineage cope with the regulatory challenges imposed by evolution of a third condensin complex. Our findings uncover a new regulator of condensins and highlight how the duplication and divergence of SMC complex components in various lineages has created new proteins with diverse functions in chromosome dynamics.
Collapse
|
37
|
Kinoshita K, Hirano T. Dynamic organization of mitotic chromosomes. Curr Opin Cell Biol 2017; 46:46-53. [PMID: 28214612 DOI: 10.1016/j.ceb.2017.01.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 01/30/2017] [Indexed: 12/19/2022]
Abstract
The assembly of rod-shaped chromosomes during mitosis is an essential prerequisite for faithful segregation of genetic information into daughter cells. Despite the long history of chromosome research, it is only recently that we have acquired powerful approaches and crucial tools that help to unlock the secret of this seemingly complex process. In particular, in vitro assays, mammalian genetics, Hi-C analyses and computer simulations have provided valuable information during the past two years. These studies are now beginning to elucidate how the core components of mitotic chromosomes, namely, histones, topoisomerase IIα and condensins, cooperate with each other to convert very long stretches of DNA into rod-shaped chromosomes.
Collapse
Affiliation(s)
- Kazuhisa Kinoshita
- Chromosome Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| |
Collapse
|
38
|
Condensin, master organizer of the genome. Chromosome Res 2017; 25:61-76. [PMID: 28181049 DOI: 10.1007/s10577-017-9553-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/19/2016] [Accepted: 01/23/2017] [Indexed: 02/06/2023]
Abstract
A fundamental requirement in nature is for a cell to correctly package and divide its replicated genome. Condensin is a mechanical multisubunit complex critical to this process. Condensin uses ATP to power conformational changes in DNA to enable to correct DNA compaction, organization, and segregation of DNA from the simplest bacteria to humans. The highly conserved nature of the condensin complex and the structural similarities it shares with the related cohesin complex have provided important clues as to how it functions in cells. The fundamental requirement for condensin in mitosis and meiosis is well established, yet the precise mechanism of action is still an open question. Mutation or removal of condensin subunits across a range of species disrupts orderly chromosome condensation leading to errors in chromosome segregation and likely death of the cell. There are divergences in function across species for condensin. Once considered to function solely in mitosis and meiosis, an accumulating body of evidence suggests that condensin has key roles in also regulating the interphase genome. This review will examine how condensin organizes our genomes, explain where and how it binds the genome at a mechanical level, and highlight controversies and future directions as the complex continues to fascinate and baffle biologists.
Collapse
|
39
|
Kagami Y, Yoshida K. The functional role for condensin in the regulation of chromosomal organization during the cell cycle. Cell Mol Life Sci 2016; 73:4591-4598. [PMID: 27402120 PMCID: PMC11108269 DOI: 10.1007/s00018-016-2305-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/24/2016] [Accepted: 07/06/2016] [Indexed: 12/23/2022]
Abstract
In all organisms, the control of cell cycle progression is a fundamental process that is essential for cell growth, development, and survival. Through each cell cycle phase, the regulation of chromatin organization is essential for natural cell proliferation and maintaining cellular homeostasis. During mitosis, the chromatin morphology is dramatically changed to have a "thread-like" shape and the condensed chromosomes are segregated equally into two daughter cells. Disruption of the mitotic chromosome architecture physically impedes chromosomal behaviors, such as chromosome alignment and chromosome segregation; therefore, the proper mitotic chromosome structure is required to maintain chromosomal stability. Accumulating evidence has demonstrated that mitotic chromosome condensation is induced by condensin complexes. Moreover, recent studies have shown that condensin also modulates interphase chromatin and regulates gene expression. This review mainly focuses on the molecular mechanisms that condensin uses to exert its functions during the cell cycle progression. Moreover, we discuss the condensin-mediated chromosomal organization in cancer cells.
Collapse
Affiliation(s)
- Yuya Kagami
- Department of Biochemistry, Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Kiyotsugu Yoshida
- Department of Biochemistry, Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo, 105-8461, Japan.
| |
Collapse
|
40
|
Yoshimura SH, Hirano T. HEAT repeats - versatile arrays of amphiphilic helices working in crowded environments? J Cell Sci 2016; 129:3963-3970. [PMID: 27802131 DOI: 10.1242/jcs.185710] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cellular proteins do not work in isolation. Instead, they often function as part of large macromolecular complexes, which are transported and concentrated into specific cellular compartments and function in a highly crowded environment. A central theme of modern cell biology is to understand how such macromolecular complexes are assembled efficiently and find their destinations faithfully. In this Opinion article, we will focus on HEAT repeats, flexible arrays of amphiphilic helices found in many eukaryotic proteins, such as karyopherins and condensins, and discuss how these uniquely designed helical repeats might underlie dynamic protein-protein interactions and support cellular functions in crowded environments. We will make bold speculations on functional similarities between the action of HEAT repeats and intrinsically disordered regions (IDRs) in macromolecular phase separation. Potential contributions of HEAT-HEAT interactions, as well as cooperation between HEATs and IDRs, to mesoscale organelle assembly will be discussed.
Collapse
Affiliation(s)
- Shige H Yoshimura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, Saitama 351-0198, Japan
| |
Collapse
|
41
|
Abstract
SMC (structural maintenance of chromosomes) complexes - which include condensin, cohesin and the SMC5-SMC6 complex - are major components of chromosomes in all living organisms, from bacteria to humans. These ring-shaped protein machines, which are powered by ATP hydrolysis, topologically encircle DNA. With their ability to hold more than one strand of DNA together, SMC complexes control a plethora of chromosomal activities. Notable among these are chromosome condensation and sister chromatid cohesion. Moreover, SMC complexes have an important role in DNA repair. Recent mechanistic insight into the function and regulation of these universal chromosomal machines enables us to propose molecular models of chromosome structure, dynamics and function, illuminating one of the fundamental entities in biology.
Collapse
|
42
|
Abstract
Condensins are large protein complexes that play a central role in chromosome organization and segregation in the three domains of life. They display highly characteristic, rod-shaped structures with SMC (structural maintenance of chromosomes) ATPases as their core subunits and organize large-scale chromosome structure through active mechanisms. Most eukaryotic species have two distinct condensin complexes whose balanced usage is adapted flexibly to different organisms and cell types. Studies of bacterial condensins provide deep insights into the fundamental mechanisms of chromosome segregation. This Review surveys both conserved features and rich variations of condensin-based chromosome organization and discusses their evolutionary implications.
Collapse
Affiliation(s)
- Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| |
Collapse
|