1
|
Warecki B, Tao L. Centralspindlin-mediated transport of RhoGEF positions the cleavage plane for cytokinesis. Sci Signal 2023; 16:eadh0601. [PMID: 37402224 PMCID: PMC10501416 DOI: 10.1126/scisignal.adh0601] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 06/13/2023] [Indexed: 07/06/2023]
Abstract
During cytokinesis, the cell membrane furrows inward along a cleavage plane. The positioning of the cleavage plane is critical to faithful cell division and is determined by the Rho guanine nucleotide exchange factor (RhoGEF)-mediated activation of the small guanosine triphosphatase RhoA and the conserved motor protein complex centralspindlin. Here, we explored whether and how centralspindlin mediates the positioning of RhoGEF. In dividing neuroblasts from Drosophila melanogaster, we observed that immediately before cleavage, first centralspindlin and then RhoGEF localized to the sites where cleavage subsequently initiated. Using in vitro assays with purified Drosophila proteins and stabilized microtubules, we found that centralspindlin directly transported RhoGEF as cargo along single microtubules and sequestered it at microtubule plus-ends for prolonged periods of time. In addition, the binding of RhoGEF to centralspindlin appeared to stimulate centralspindlin motor activity. Thus, the motor activity and microtubule association of centralspindlin can translocate RhoGEF to areas where microtubule plus-ends are abundant, such as at overlapping astral microtubules, to locally activate RhoA and accurately position the cleavage plane during cell division.
Collapse
Affiliation(s)
- Brandt Warecki
- Department of Biology, University of Hawai’i at Hilo, HI 96720, USA
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz; Santa Cruz, CA 95064, USA
| | - Li Tao
- Department of Biology, University of Hawai’i at Hilo, HI 96720, USA
| |
Collapse
|
2
|
Poulos A, Budaitis BG, Verhey KJ. Single-motor and multi-motor motility properties of kinesin-6 family members. Biol Open 2022; 11:276958. [PMID: 36178151 PMCID: PMC9581516 DOI: 10.1242/bio.059533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 09/22/2022] [Indexed: 12/31/2022] Open
Abstract
Kinesin motor proteins are responsible for orchestrating a variety of microtubule-based processes including intracellular transport, cell division, cytoskeletal organization, and cilium function. Members of the kinesin-6 family play critical roles in anaphase and cytokinesis during cell division as well as in cargo transport and microtubule organization during interphase, however little is known about their motility properties. We find that truncated versions of MKLP1 (HsKIF23), MKLP2 (HsKIF20A), and HsKIF20B largely interact statically with microtubules as single molecules but can also undergo slow, processive motility, most prominently for MKLP2. In multi-motor assays, all kinesin-6 proteins were able to drive microtubule gliding and MKLP1 and KIF20B were also able to drive robust transport of both peroxisomes, a low-load cargo, and Golgi, a high-load cargo, in cells. In contrast, MKLP2 showed minimal transport of peroxisomes and was unable to drive Golgi dispersion. These results indicate that the three mammalian kinesin-6 motor proteins can undergo processive motility but differ in their ability to generate forces needed to drive cargo transport and microtubule organization in cells.
Collapse
Affiliation(s)
- Andrew Poulos
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Breane G. Budaitis
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Authors for correspondence (; )
| | - Kristen J. Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Authors for correspondence (; )
| |
Collapse
|
3
|
From primordial germ cells to spermatids in Caenorhabditis elegans. Semin Cell Dev Biol 2021; 127:110-120. [PMID: 34930663 DOI: 10.1016/j.semcdb.2021.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/17/2021] [Accepted: 12/07/2021] [Indexed: 12/24/2022]
Abstract
Development of a syncytial germline for gamete formation requires complex regulation of cytokinesis and cytoplasmic remodeling. Recently, several uncovered cellular events have been investigated in the Caenorhabditis elegans (C. elegans) germline. In these cellular processes, the factors involved in contractility are highly conserved with those of mitosis and meiosis. However, the underlying regulatory mechanisms are far more complicated than previously thought, likely due to the single syncytial germline structure. In this review, we highlight how the proteins involved in contractility ensure faithful cell division in different cellular contexts and how they contribute to maintaining intercellular bridge stability. In addition, we discuss the current understanding of the cellular events of cytokinesis and cytoplasmic remodeling during the development of the C. elegans germline, including progenitor germ cells, germ cells, and spermatocytes. Comparisons are made with relevant systems in Drosophila melanogaster (D. melanogaster) and other animal models.
Collapse
|
4
|
Mechanistic insights into central spindle assembly mediated by the centralspindlin complex. Proc Natl Acad Sci U S A 2021; 118:2112039118. [PMID: 34588311 PMCID: PMC8501884 DOI: 10.1073/pnas.2112039118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2021] [Indexed: 02/07/2023] Open
Abstract
Centralspindlin bundles microtubules to assemble the central spindle, being essential for cytokinesis of the cell. It is a heterotetramer formed by ZEN-4 and CYK-4 in a 2:2 manner. We determined the crystal structures of centralspindlin, which revealed the detailed mechanism of complex formation. We found that centralspindlin clustered to undergo liquid–liquid phase separation (LLPS), which depended on the complementary charged residues located at ZEN-4 and CYK-4, respectively, explaining the synergy of the two subunits for the function. The LLPS of centralspindlin is critical for the microtubule bundling activity in vitro and the assembly of the central spindle in vivo. Together, our study provides angstrom-to-micron mechanistic insights into central spindle assembly mediated by the centralspindlin complex. The central spindle spatially and temporally regulates the formation of division plane during cytokinesis in animal cells. The heterotetrameric centralspindlin complex bundles microtubules to assemble the central spindle, the mechanism of which is poorly understood. Here, we determined the crystal structures of the molecular backbone of ZEN-4/CYK-4 centralspindlin from Caenorhabditis elegans, which revealed the detailed mechanism of complex formation. The molecular backbone of centralspindlin has the intrinsic propensity to undergo liquid–liquid phase separation. The condensation of centralspindlin requires two patches of basic residues at ZEN-4 and multiple acidic residues at the intrinsically disordered region of CYK-4, explaining the synergy of the two subunits for the function. These complementary charged residues were critical for the microtubule bundling activity of centralspindlin in vitro and for the assembly of the central spindle in vivo. Together, our findings provide insights into the mechanism of central spindle assembly mediated by centralspindlin through charge-driven macromolecular condensation.
Collapse
|
5
|
Maruyama Y, Sugawa M, Yamaguchi S, Davies T, Osaki T, Kobayashi T, Yamagishi M, Takeuchi S, Mishima M, Yajima J. CYK4 relaxes the bias in the off-axis motion by MKLP1 kinesin-6. Commun Biol 2021; 4:180. [PMID: 33568771 PMCID: PMC7876049 DOI: 10.1038/s42003-021-01704-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 01/14/2021] [Indexed: 12/18/2022] Open
Abstract
Centralspindlin, a complex of the MKLP1 kinesin-6 and CYK4 GAP subunits, plays key roles in metazoan cytokinesis. CYK4-binding to the long neck region of MKLP1 restricts the configuration of the two MKLP1 motor domains in the centralspindlin. However, it is unclear how the CYK4-binding modulates the interaction of MKLP1 with a microtubule. Here, we performed three-dimensional nanometry of a microbead coated with multiple MKLP1 molecules on a freely suspended microtubule. We found that beads driven by dimeric MKLP1 exhibited persistently left-handed helical trajectories around the microtubule axis, indicating torque generation. By contrast, centralspindlin, like monomeric MKLP1, showed similarly left-handed but less persistent helical movement with occasional rightward movements. Analysis of the fluctuating helical movement indicated that the MKLP1 stochastically makes off-axis motions biased towards the protofilament on the left. CYK4-binding to the neck domains in MKLP1 enables more flexible off-axis motion of centralspindlin, which would help to avoid obstacles along crowded spindle microtubules. Analysing the 3D movement of MKLP1 motors, Maruyama et al. find that dimeric C. elegans MKLP1 drives a left-handed helical motion around the microtubule with minimum protofilament switching to the right side whereas less persistent motions are driven by monomers or by heterotetramers with CYK4. These findings suggest how obstacles along crowded spindle microtubules may be avoided by CYK4 binding to MKLP1.
Collapse
Affiliation(s)
- Yohei Maruyama
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Mitsuhiro Sugawa
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Shin Yamaguchi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Tim Davies
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.,Department of Biosciences, Durham University, Durham, UK
| | - Toshihisa Osaki
- Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Takuya Kobayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Masahiko Yamagishi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Shoji Takeuchi
- Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo, Japan.,Research Center for complex Systems Biology, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Masanori Mishima
- Centre for Mechanochemical Cell Biology and Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK.
| | - Junichiro Yajima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan. .,Komaba Institute for Science, The University of Tokyo, Meguro-ku, Tokyo, Japan. .,Research Center for complex Systems Biology, The University of Tokyo, Meguro-ku, Tokyo, Japan.
| |
Collapse
|
6
|
Abstract
The active form of the small GTPase RhoA is necessary and sufficient for formation of a cytokinetic furrow in animal cells. Despite the conceptual simplicity of the process, the molecular mechanisms that control it are intricate and involve redundancy at multiple levels. Here, we discuss our current knowledge of the mechanisms underlying spatiotemporal regulation of RhoA during cytokinesis by upstream activators. The direct upstream activator, the RhoGEF Ect2, requires activation due to autoinhibition. Ect2 is primarily activated by the centralspindlin complex, which contains numerous domains that regulate its subcellular localization, oligomeric state, and Ect2 activation. We review the functions of these domains and how centralspindlin is regulated to ensure correctly timed, equatorial RhoA activation. Highlighting recent evidence, we propose that although centralspindlin does not always prominently accumulate on the plasma membrane, it is the site where it promotes RhoA activation during cytokinesis.
Collapse
|
7
|
Raghuraman H, Chatterjee S, Das A. Site-Directed Fluorescence Approaches for Dynamic Structural Biology of Membrane Peptides and Proteins. Front Mol Biosci 2019; 6:96. [PMID: 31608290 PMCID: PMC6774292 DOI: 10.3389/fmolb.2019.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Membrane proteins mediate a number of cellular functions and are associated with several diseases and also play a crucial role in pathogenicity. Due to their importance in cellular structure and function, they are important drug targets for ~60% of drugs available in the market. Despite the technological advancement and recent successful outcomes in determining the high-resolution structural snapshot of membrane proteins, the mechanistic details underlining the complex functionalities of membrane proteins is least understood. This is largely due to lack of structural dynamics information pertaining to different functional states of membrane proteins in a membrane environment. Fluorescence spectroscopy is a widely used technique in the analysis of functionally-relevant structure and dynamics of membrane protein. This review is focused on various site-directed fluorescence (SDFL) approaches and their applications to explore structural information, conformational changes, hydration dynamics, and lipid-protein interactions of important classes of membrane proteins that include the pore-forming peptides/proteins, ion channels/transporters and G-protein coupled receptors.
Collapse
Affiliation(s)
- H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
| | | | | |
Collapse
|
8
|
Abstract
Division of amoebas, fungi, and animal cells into two daughter cells at the end of the cell cycle depends on a common set of ancient proteins, principally actin filaments and myosin-II motors. Anillin, formins, IQGAPs, and many other proteins regulate the assembly of the actin filaments into a contractile ring positioned between the daughter nuclei by different mechanisms in fungi and animal cells. Interactions of myosin-II with actin filaments produce force to assemble and then constrict the contractile ring to form a cleavage furrow. Contractile rings disassemble as they constrict. In some cases, knowledge about the numbers of participating proteins and their biochemical mechanisms has made it possible to formulate molecularly explicit mathematical models that reproduce the observed physical events during cytokinesis by computer simulations.
Collapse
Affiliation(s)
- Thomas D Pollard
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA;
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103, USA
- Department of Cell Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA;
| |
Collapse
|
9
|
Abstract
Division of amoebas, fungi, and animal cells into two daughter cells at the end of the cell cycle depends on a common set of ancient proteins, principally actin filaments and myosin-II motors. Anillin, formins, IQGAPs, and many other proteins regulate the assembly of the actin filaments into a contractile ring positioned between the daughter nuclei by different mechanisms in fungi and animal cells. Interactions of myosin-II with actin filaments produce force to assemble and then constrict the contractile ring to form a cleavage furrow. Contractile rings disassemble as they constrict. In some cases, knowledge about the numbers of participating proteins and their biochemical mechanisms has made it possible to formulate molecularly explicit mathematical models that reproduce the observed physical events during cytokinesis by computer simulations.
Collapse
Affiliation(s)
- Thomas D Pollard
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA;
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8103, USA
- Department of Cell Biology, Yale University, New Haven, Connecticut 06520-8103, USA
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA;
| |
Collapse
|
10
|
Von Stetina SE, Liang J, Marnellos G, Mango SE. Temporal regulation of epithelium formation mediated by FoxA, MKLP1, MgcRacGAP, and PAR-6. Mol Biol Cell 2017; 28:2042-2065. [PMID: 28539408 PMCID: PMC5509419 DOI: 10.1091/mbc.e16-09-0644] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 05/18/2017] [Accepted: 05/18/2017] [Indexed: 12/15/2022] Open
Abstract
During embryo morphogenesis, minor epithelia are generated after, and then form bridges between, major epithelia (e.g., epidermis and gut). In Caenorhabditis elegans, this delay is regulated by four proteins that control production and localization of polarity proteins: the pioneer factor PHA-4/FoxA, kinesin ZEN-4/MKLP1, its partner CYK-4/MgcRacGAP, and PAR-6. To establish the animal body plan, embryos link the external epidermis to the internal digestive tract. In Caenorhabditis elegans, this linkage is achieved by the arcade cells, which form an epithelial bridge between the foregut and epidermis, but little is known about how development of these three epithelia is coordinated temporally. The arcade cell epithelium is generated after the epidermis and digestive tract epithelia have matured, ensuring that both organs can withstand the mechanical stress of embryo elongation; mistiming of epithelium formation leads to defects in morphogenesis. Using a combination of genetic, bioinformatic, and imaging approaches, we find that temporal regulation of the arcade cell epithelium is mediated by the pioneer transcription factor and master regulator PHA-4/FoxA, followed by the cytoskeletal regulator and kinesin ZEN-4/MKLP1 and the polarity protein PAR-6. We show that PHA-4 directly activates mRNA expression of a broad cohort of epithelial genes, including junctional factor dlg-1. Accumulation of DLG-1 protein is delayed by ZEN-4, acting in concert with its binding partner CYK-4/MgcRacGAP. Our structure–function analysis suggests that nuclear and kinesin functions are dispensable, whereas binding to CYK-4 is essential, for ZEN-4 function in polarity. Finally, PAR-6 is necessary to localize polarity proteins such as DLG-1 within adherens junctions and at the apical surface, thereby generating arcade cell polarity. Our results reveal that the timing of a landmark event during embryonic morphogenesis is mediated by the concerted action of four proteins that delay the formation of an epithelial bridge until the appropriate time. In addition, we find that mammalian FoxA associates with many epithelial genes, suggesting that direct regulation of epithelial identity may be a conserved feature of FoxA factors and a contributor to FoxA function in development and cancer.
Collapse
Affiliation(s)
- Stephen E Von Stetina
- Department of Molecular and Cellular Biology, Harvard University, Cambridge; MA 02138
| | - Jennifer Liang
- Department of Molecular and Cellular Biology, Harvard University, Cambridge; MA 02138
| | - Georgios Marnellos
- Informatics and Scientific Applications, Science Division, Faculty of Arts and Sciences, Harvard University, Cambridge; MA 02138
| | - Susan E Mango
- Department of Molecular and Cellular Biology, Harvard University, Cambridge; MA 02138
| |
Collapse
|
11
|
Mishima M. Preparation of centralspindlin as an active heterotetramer of kinesin and GTPase activating protein subunits for in vitro structural and functional assays. Methods Cell Biol 2017; 137:371-385. [DOI: 10.1016/bs.mcb.2016.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|
12
|
Mishima M. Centralspindlin in Rappaport’s cleavage signaling. Semin Cell Dev Biol 2016; 53:45-56. [DOI: 10.1016/j.semcdb.2016.03.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 03/02/2016] [Indexed: 02/07/2023]
|
13
|
Tao L, Fasulo B, Warecki B, Sullivan W. Tum/RacGAP functions as a switch activating the Pav/kinesin-6 motor. Nat Commun 2016; 7:11182. [PMID: 27091402 PMCID: PMC4838857 DOI: 10.1038/ncomms11182] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 02/26/2016] [Indexed: 11/24/2022] Open
Abstract
Centralspindlin is essential for central spindle and cleavage furrow formation. Drosophila centralspindlin consists of a kinesin-6 motor (Pav/kinesin-6) and a GTPase-activating protein (Tum/RacGAP). Centralspindlin localization to the central spindle is mediated by Pav/kinesin-6. While Tum/RacGAP has well-documented scaffolding functions, whether it influences Pav/kinesin-6 function is less well-explored. Here we demonstrate that both Pav/kinesin-6 and the centralspindlin complex (co-expressed Pav/Tum) have strong microtubule bundling activity. Centralspindlin also has robust plus-end-directed motility. In contrast, Pav/kinesin-6 alone cannot move microtubules. However, the addition of Tum/RacGAP or a 65 amino acid Tum/RacGAP fragment to Pav/kinesin-6 restores microtubule motility. Further, ATPase assays reveal that microtubule-stimulated ATPase activity of centralspindlin is seven times higher than that of Pav/kinesin-6. These findings are supported by in vivo studies demonstrating that in Tum/RacGAP-depleted S2 Drosophila cells, Pav/kinesin-6 exhibits severely reduced localization to the central spindle and an abnormal concentration at the centrosomes. Centralspindlin consists of dimeric kinesin-6 and dimeric RacGAP, and is involved in the organization of anaphase midzone microtubules. Here, the authors show that the RacGAP is needed for motor activity at the plus-end of microtubules, but not for the bundling activity associated with kinesin-6.
Collapse
Affiliation(s)
- Li Tao
- Department of Biology, University of Hawaii at Hilo, 200 West Kawili Street, Hilo, Hawaii 96720, USA.,Department of Molecular, Cellular and Developmental Biology, University of California, Santa Cruz, California 95064, USA
| | - Barbara Fasulo
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Cruz, California 95064, USA
| | - Brandt Warecki
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Cruz, California 95064, USA
| | - William Sullivan
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Cruz, California 95064, USA
| |
Collapse
|
14
|
Davies T, Kodera N, Kaminski Schierle GS, Rees E, Erdelyi M, Kaminski CF, Ando T, Mishima M. CYK4 promotes antiparallel microtubule bundling by optimizing MKLP1 neck conformation. PLoS Biol 2015; 13:e1002121. [PMID: 25875822 PMCID: PMC4395295 DOI: 10.1371/journal.pbio.1002121] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 03/05/2015] [Indexed: 11/19/2022] Open
Abstract
Centralspindlin, a constitutive 2:2 heterotetramer of MKLP1 (a kinesin-6) and the non-motor subunit CYK4, plays important roles in cytokinesis. It is crucial for the formation of central spindle microtubule bundle structure. Its accumulation at the central antiparallel overlap zone is key for recruitment and regulation of downstream cytokinesis factors and for stable anchoring of the plasma membrane at the midbody. Both MKLP1 and CYK4 are required for efficient microtubule bundling. However, the mechanism by which CYK4 contributes to this is unclear. Here we performed structural and functional analyses of centralspindlin using high-speed atomic force microscopy, Fӧrster resonance energy transfer analysis, and in vitro reconstitution. Our data reveal that CYK4 binds to a globular mass in the atypically long MKLP1 neck domain between the catalytic core and the coiled coil and thereby reconfigures the two motor domains in the MKLP1 dimer to be suitable for antiparallel microtubule bundling. Our work provides insights into the microtubule bundling during cytokinesis and into the working mechanisms of the kinesins with non-canonical neck structures. Cell division depends on the antiparallel bundling of microtubules by a motor complex called centralpindlin. This study reveals how the centralspindlin non-motor subunit CYK4 reconfigures the motor domains of the kinesin subunit MKLP1 to help it carry out this role. Cell division requires coordination of many different cellular components. Cytokinesis is the process by which the cytoplasm divides between the two forming daughter cells. During cytokinesis, centralspindlin is truly central, as it organizes microtubule bundle structures, recruits other factors to the site of division, and anchors the plasma membrane at the inter-cellular bridge while the two daughter cells are waiting for the final separation. Centralspindlin is a heterotetramer composed of two molecules of a kinesin-6 motor subunit, MKLP1, and two molecules of the second subunit, CYK4. For efficient microtubule bundling, both the microtubule motor subunit MKLP1 and the non-motor CYK4 subunit are required. However, it has remained unclear how CYK4 contributes to this activity. Here, we took a combinatorial approach to investigate this process, using in vitro reconstitution and structural analyses by atomic force microscopy and Förster resonance energy transfer. We revealed that the CYK4 dimer binds to a hitherto unknown globular domain at the neck of the MKLP1 dimer and optimizes the configuration of two motor domains, making them suitable for antiparallel microtubule bundling. This provides novel insight into how other kinesin superfamily molecules with non-canonical neck structures may work.
Collapse
Affiliation(s)
- Tim Davies
- Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Noriyuki Kodera
- Department of Physics and Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, Japan
| | - Gabriele S. Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge, United Kingdom
| | - Eric Rees
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge, United Kingdom
| | - Miklos Erdelyi
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge, United Kingdom
| | - Clemens F. Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge, United Kingdom
| | - Toshio Ando
- Department of Physics and Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, Japan
| | - Masanori Mishima
- Biomedical Cell Biology, Warwick Medical School, University of Warwick, Gibbet Hill Road, Coventry, United Kingdom
- * E-mail:
| |
Collapse
|