1
|
Ye X, Kim T, Geyer EA, Rice LM. Insights into allosteric control of microtubule dynamics from a buried β-tubulin mutation that causes faster growth and slower shrinkage. Protein Sci 2020; 29:1429-1439. [PMID: 32077153 DOI: 10.1002/pro.3842] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 01/27/2023]
Abstract
αβ-tubulin subunits cycle through a series of different conformations in the polymer lattice during microtubule growing and shrinking. How these allosteric responses to different tubulin:tubulin contacts contribute to microtubule dynamics, and whether the contributions are evolutionarily conserved, remains poorly understood. Here, we sought to determine whether the microtubule-stabilizing effects (slower shrinking) of the β:T238A mutation we previously observed using yeast αβ-tubulin would generalize to mammalian microtubules. Using recombinant human microtubules as a model, we found that the mutation caused slow microtubule shrinking, indicating that this effect of the mutation is indeed conserved. However, unlike in yeast, β:T238A human microtubules grew faster than wild-type and the mutation did not appear to attenuate the conformational change associated with guanosine 5'-triphosphate (GTP) hydrolysis in the lattice. We conclude that the assembly-dependent conformational change in αβ-tubulin can contribute to determine the rates of microtubule growing as well as shrinking. Our results also suggest that an allosteric perturbation like the β:T238A mutation can alter the behavior of terminal subunits without accompanying changes in the conformation of fully surrounded subunits in the body of the microtubule.
Collapse
Affiliation(s)
- Xuecheng Ye
- UT Southwestern Medical Center, Departments of Biophysics and Biochemistry, Dallas, Texas, USA
| | - Tae Kim
- UT Southwestern Medical Center, Departments of Biophysics and Biochemistry, Dallas, Texas, USA
| | - Elisabeth A Geyer
- UT Southwestern Medical Center, Departments of Biophysics and Biochemistry, Dallas, Texas, USA
| | - Luke M Rice
- UT Southwestern Medical Center, Departments of Biophysics and Biochemistry, Dallas, Texas, USA
| |
Collapse
|
2
|
Miller MP, Evans RK, Zelter A, Geyer EA, MacCoss MJ, Rice LM, Davis TN, Asbury CL, Biggins S. Kinetochore-associated Stu2 promotes chromosome biorientation in vivo. PLoS Genet 2019; 15:e1008423. [PMID: 31584935 PMCID: PMC6795502 DOI: 10.1371/journal.pgen.1008423] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 10/16/2019] [Accepted: 09/13/2019] [Indexed: 12/31/2022] Open
Abstract
Accurate segregation of chromosomes to daughter cells is a critical aspect of cell division. It requires the kinetochores on duplicated chromosomes to biorient, attaching to microtubules from opposite poles of the cell. Bioriented attachments come under tension, while incorrect attachments lack tension and must be released to allow proper attachments to form. A well-studied error correction pathway is mediated by the Aurora B kinase, which destabilizes low tension-bearing attachments. We recently discovered that in vitro, kinetochores display an additional intrinsic tension-sensing pathway that utilizes Stu2. The contribution of kinetochore-associated Stu2 to error correction in cells, however, was unknown. Here, we identify a Stu2 mutant that abolishes its kinetochore function and show that it causes biorientation defects in vivo. We also show that this Stu2-mediated pathway functions together with the Aurora B-mediated pathway. Altogether, our work indicates that cells employ multiple pathways to ensure biorientation and the accuracy of chromosome segregation. The precise regulation of cell division is critical to processes such as self-renewal, proliferation and development. A key event in the cell cycle is the partitioning of every pair of duplicated chromosomes to daughter cells. Defects in chromosome partitioning lead to aneuploidy, a condition that is a common hallmark of cancer cells and the cause of some birth defects. Chromosomes segregate using their kinetochores, the specialized protein structures that are assembled on centromeric DNA sequences and attach to spindle microtubules. Here, we report that a protein that associates with kinetochores called Stu2 ensures that each kinetochore attaches to the proper microtubules. We identified a Stu2 mutant that does not associate with kinetochores and found that it generates aneuploidy. Together, our work identifies a previously unknown mechanism where cells ensure that chromosomes are accurately inherited during cell division.
Collapse
Affiliation(s)
- Matthew P. Miller
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Rena K. Evans
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Alex Zelter
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, United States of America
| | - Elisabeth A. Geyer
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, Texas, United States of America
| | - Michael J. MacCoss
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Luke M. Rice
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, Texas, United States of America
| | - Trisha N. Davis
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, United States of America
| | - Charles L. Asbury
- Department of Physiology & Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * E-mail:
| |
Collapse
|
3
|
Abstract
Stu2/XMAP215 microtubule polymerases use multiple tubulin-binding TOG domains and a lattice-binding basic region to processively promote faster elongation. How the domain composition and organization of these proteins dictate polymerase activity, end localization, and processivity is unknown. We show that polymerase activity does not require different kinds of TOGs, nor are there strict requirements for how the TOGs are linked. We identify an unexpected antagonism between the tubulin-binding TOGs and the lattice-binding basic region: lattice binding by the basic region is weak when at least two TOGs engage tubulins, strong when TOGs are empty. End-localization of Stu2 requires unpolymerized tubulin, at least two TOGs, and polymerase competence. We propose a ‘ratcheting’ model for processivity: transfer of tubulin from TOGs to the lattice activates the basic region, retaining the polymerase at the end for subsequent rounds of tubulin binding and incorporation. These results clarify design principles of the polymerase.
Collapse
Affiliation(s)
- Elisabeth A Geyer
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Matthew P Miller
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Chad A Brautigam
- Departments of Biophysics and Microbiology, UT Southwestern Medical Center, Dallas, United States
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Luke M Rice
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, United States
| |
Collapse
|
4
|
Howes SC, Geyer EA, LaFrance B, Zhang R, Kellogg EH, Westermann S, Rice LM, Nogales E. Structural and functional differences between porcine brain and budding yeast microtubules. Cell Cycle 2018; 17:278-287. [PMID: 29278985 PMCID: PMC5914886 DOI: 10.1080/15384101.2017.1415680] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The cytoskeleton of eukaryotic cells relies on microtubules to perform many essential functions. We have previously shown that, in spite of the overall conservation in sequence and structure of tubulin subunits across species, there are differences between mammalian and budding yeast microtubules with likely functional consequences for the cell. Here we expand our structural and function comparison of yeast and porcine microtubules to show different distribution of protofilament number in microtubules assembled in vitro from these two species. The different geometry at lateral contacts between protofilaments is likely due to a more polar interface in yeast. We also find that yeast tubulin forms longer and less curved oligomers in solution, suggesting stronger tubulin:tubulin interactions along the protofilament. Finally, we observed species-specific plus-end tracking activity for EB proteins: yeast Bim1 tracked yeast but not mammalian MTs, and human EB1 tracked mammalian but not yeast MTs. These findings further demonstrate that subtle sequence differences in tubulin sequence can have significant structural and functional consequences in microtubule structure and behavior.
Collapse
Affiliation(s)
- Stuart C Howes
- a Biophysics Graduate Group , UC Berkeley , CA 94720 , USA and Department of Molecular Cell Biology , Leiden University Medical Center , 2333 ZC Leiden , Netherlands
| | - Elisabeth A Geyer
- b UT Southwestern Medical Center , Departments of Biophysics and Biochemistry , Dallas , TX 75390 , USA
| | - Benjamin LaFrance
- c Molecular and Cell Biology Graduate Program , UC Berkeley , CA 94720 , USA
| | - Rui Zhang
- d Molecular Biophysics and Integrated Bioimaging , Lawrence Berkeley National Laboratory , CA 94720 , USA.,e Howard Hughes Medical Institute , UC Berkeley , CA 94720-3220 , USA.,f Department of Biochemistry and Molecular Biophysics , Washington University School of Medicine , St. Louis , MO 63110 , USA
| | - Elizabeth H Kellogg
- d Molecular Biophysics and Integrated Bioimaging , Lawrence Berkeley National Laboratory , CA 94720 , USA.,e Howard Hughes Medical Institute , UC Berkeley , CA 94720-3220 , USA
| | - Stefan Westermann
- g Research Institute of Molecular Pathology , Dr. Bohr-Gasse 7, 1030 Vienna , Austria
| | - Luke M Rice
- b UT Southwestern Medical Center , Departments of Biophysics and Biochemistry , Dallas , TX 75390 , USA
| | - Eva Nogales
- d Molecular Biophysics and Integrated Bioimaging , Lawrence Berkeley National Laboratory , CA 94720 , USA.,e Howard Hughes Medical Institute , UC Berkeley , CA 94720-3220 , USA.,h Molecular and Cell Biology Department and QB3 Institute , UC Berkeley , CA 94720 , USA
| |
Collapse
|
5
|
Arellano-Santoyo H, Geyer EA, Stokasimov E, Chen GY, Su X, Hancock W, Rice LM, Pellman D. A Tubulin Binding Switch Underlies Kip3/Kinesin-8 Depolymerase Activity. Dev Cell 2017; 42:37-51.e8. [PMID: 28697331 DOI: 10.1016/j.devcel.2017.06.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 05/22/2017] [Accepted: 06/09/2017] [Indexed: 02/04/2023]
Abstract
Kinesin-8 motors regulate the size of microtubule structures, using length-dependent accumulation at the plus end to preferentially disassemble long microtubules. Despite extensive study, the kinesin-8 depolymerase mechanism remains under debate. Here, we provide evidence for an alternative, tubulin curvature-sensing model of microtubule depolymerization by the budding yeast kinesin-8, Kip3. Kinesin-8/Kip3 uses ATP hydrolysis, like other kinesins, for stepping on the microtubule lattice, but at the plus end Kip3 undergoes a switch: its ATPase activity is suppressed when it binds tightly to the curved conformation of tubulin. This prolongs plus-end binding, stabilizes protofilament curvature, and ultimately promotes microtubule disassembly. The tubulin curvature-sensing model is supported by our identification of Kip3 structural elements necessary and sufficient for plus-end binding and depolymerase activity, as well as by the identification of an α-tubulin residue specifically required for the Kip3-curved tubulin interaction. Together, these findings elucidate a major regulatory mechanism controlling the size of cellular microtubule structures.
Collapse
Affiliation(s)
- Hugo Arellano-Santoyo
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | | | - Ema Stokasimov
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
| | - Geng-Yuan Chen
- Department of Biomedical Engineering, Penn State University, University Park, PA 16802, USA
| | - Xiaolei Su
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94143, USA
| | - William Hancock
- Department of Biomedical Engineering, Penn State University, University Park, PA 16802, USA
| | - Luke M Rice
- Department of Biophysics, UT Southwestern, Dallas, TX 75390, USA
| | - David Pellman
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA.
| |
Collapse
|
6
|
Howes SC, Geyer EA, LaFrance B, Zhang R, Kellogg EH, Westermann S, Rice LM, Nogales E. Structural differences between yeast and mammalian microtubules revealed by cryo-EM. J Cell Biol 2017; 216:2669-2677. [PMID: 28652389 PMCID: PMC5584162 DOI: 10.1083/jcb.201612195] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 03/31/2017] [Accepted: 05/30/2017] [Indexed: 01/03/2023] Open
Abstract
Yeast MTs do not appear to undergo the lattice compaction seen in mammalian MTs upon GTP hydrolysis. Binding of the +TIP Bim1, both between and within αβ-tubulin dimers, causes compaction of yeast MTs and their rapid disassembly. Microtubules are polymers of αβ-tubulin heterodimers essential for all eukaryotes. Despite sequence conservation, there are significant structural differences between microtubules assembled in vitro from mammalian or budding yeast tubulin. Yeast MTs were not observed to undergo compaction at the interdimer interface as seen for mammalian microtubules upon GTP hydrolysis. Lack of compaction might reflect slower GTP hydrolysis or a different degree of allosteric coupling in the lattice. The microtubule plus end–tracking protein Bim1 binds yeast microtubules both between αβ-tubulin heterodimers, as seen for other organisms, and within tubulin dimers, but binds mammalian tubulin only at interdimer contacts. At the concentrations used in cryo-electron microscopy, Bim1 causes the compaction of yeast microtubules and induces their rapid disassembly. Our studies demonstrate structural differences between yeast and mammalian microtubules that likely underlie their differing polymerization dynamics. These differences may reflect adaptations to the demands of different cell size or range of physiological growth temperatures.
Collapse
Affiliation(s)
- Stuart C Howes
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA
| | - Elisabeth A Geyer
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX
| | - Benjamin LaFrance
- Molecular and Cell Biology Graduate Program, University of California, Berkeley, Berkeley, CA
| | - Rui Zhang
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA
| | - Elizabeth H Kellogg
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA
| | - Stefan Westermann
- Department of Molecular Genetics, Center for Medical Biotechnology, University of Duisburg-Essen, Essen, Germany
| | - Luke M Rice
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX
| | - Eva Nogales
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA .,Department of Molecular Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA
| |
Collapse
|
7
|
Driver JW, Geyer EA, Bailey ME, Rice LM, Asbury CL. Direct measurement of conformational strain energy in protofilaments curling outward from disassembling microtubule tips. eLife 2017. [PMID: 28628007 PMCID: PMC5515574 DOI: 10.7554/elife.28433] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Disassembling microtubules can generate movement independently of motor enzymes, especially at kinetochores where they drive chromosome motility. A popular explanation is the 'conformational wave' model, in which protofilaments pull on the kinetochore as they curl outward from a disassembling tip. But whether protofilaments can work efficiently via this spring-like mechanism has been unclear. By modifying a previous assay to use recombinant tubulin and feedback-controlled laser trapping, we directly demonstrate the spring-like elasticity of curling protofilaments. Measuring their mechanical work output suggests they carry ~25% of the energy of GTP hydrolysis as bending strain, enabling them to drive movement with efficiency similar to conventional motors. Surprisingly, a β-tubulin mutant that dramatically slows disassembly has no effect on work output, indicating an uncoupling of disassembly speed from protofilament strain. These results show the wave mechanism can make a major contribution to kinetochore motility and establish a direct approach for measuring tubulin mechano-chemistry.
Collapse
Affiliation(s)
- Jonathan W Driver
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Elisabeth A Geyer
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Megan E Bailey
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Luke M Rice
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| |
Collapse
|
8
|
Driver JW, Geyer EA, Bailey ME, Rice LM, Asbury CL. Direct Measurement of the Force-Generating Capacity of Protofilaments Curling Outward from Disassembling Microtubule Tips. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.3043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
9
|
Piedra FA, Kim T, Garza ES, Geyer EA, Burns A, Ye X, Rice LM. GDP-to-GTP exchange on the microtubule end can contribute to the frequency of catastrophe. Mol Biol Cell 2016; 27:3515-3525. [PMID: 27146111 PMCID: PMC5221584 DOI: 10.1091/mbc.e16-03-0199] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 04/26/2016] [Indexed: 11/11/2022] Open
Abstract
Microtubules are dynamic polymers of αβ-tubulin that have essential roles in chromosome segregation and organization of the cytoplasm. Catastrophe-the switch from growing to shrinking-occurs when a microtubule loses its stabilizing GTP cap. Recent evidence indicates that the nucleotide on the microtubule end controls how tightly an incoming subunit will be bound (trans-acting GTP), but most current models do not incorporate this information. We implemented trans-acting GTP into a computational model for microtubule dynamics. In simulations, growing microtubules often exposed terminal GDP-bound subunits without undergoing catastrophe. Transient GDP exposure on the growing plus end slowed elongation by reducing the number of favorable binding sites on the microtubule end. Slower elongation led to erosion of the GTP cap and an increase in the frequency of catastrophe. Allowing GDP-to-GTP exchange on terminal subunits in simulations mitigated these effects. Using mutant αβ-tubulin or modified GTP, we showed experimentally that a more readily exchangeable nucleotide led to less frequent catastrophe. Current models for microtubule dynamics do not account for GDP-to-GTP exchange on the growing microtubule end, so our findings provide a new way of thinking about the molecular events that initiate catastrophe.
Collapse
Affiliation(s)
- Felipe-Andrés Piedra
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Tae Kim
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Emily S Garza
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Elisabeth A Geyer
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Alexander Burns
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Xuecheng Ye
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Luke M Rice
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| |
Collapse
|
10
|
Geyer EA, Majumdar S, Rice LM. May I check your cap? eLife 2016; 5:e15570. [PMID: 27050617 PMCID: PMC4829414 DOI: 10.7554/elife.15570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 04/01/2016] [Indexed: 11/21/2022] Open
Abstract
Modernizing a classic technique to study microtubules has revealed that the stability of a microtubule is related to its growth rate.
Collapse
Affiliation(s)
- Elisabeth A Geyer
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Shreoshi Majumdar
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Luke M Rice
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, United States
| |
Collapse
|
11
|
Geyer EA, Burns A, Lalonde BA, Ye X, Piedra FA, Huffaker TC, Rice LM. A mutation uncouples the tubulin conformational and GTPase cycles, revealing allosteric control of microtubule dynamics. eLife 2015; 4:e10113. [PMID: 26439009 PMCID: PMC4728127 DOI: 10.7554/elife.10113] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/06/2015] [Indexed: 11/18/2022] Open
Abstract
Microtubule dynamic instability depends on the GTPase activity of the polymerizing αβ-tubulin subunits, which cycle through at least three distinct conformations as they move into and out of microtubules. How this conformational cycle contributes to microtubule growing, shrinking, and switching remains unknown. Here, we report that a buried mutation in αβ-tubulin yields microtubules with dramatically reduced shrinking rate and catastrophe frequency. The mutation causes these effects by suppressing a conformational change that normally occurs in response to GTP hydrolysis in the lattice, without detectably changing the conformation of unpolymerized αβ-tubulin. Thus, the mutation weakens the coupling between the conformational and GTPase cycles of αβ-tubulin. By showing that the mutation predominantly affects post-GTPase conformational and dynamic properties of microtubules, our data reveal that the strength of the allosteric response to GDP in the lattice dictates the frequency of catastrophe and the severity of rapid shrinking. DOI:http://dx.doi.org/10.7554/eLife.10113.001 Protein filaments called microtubules help move cargo around inside cells. Chromosomes, which contain the cell’s genetic blueprints, are the microtubule’s most precious cargo. Before a cell divides, microtubules grow from the ends of the dividing cell towards the middle, where they attach to the chromosomes that are lined up along the centerline. Then the microtubules shrink and drag the chromosomes back to the opposite ends of the cell. This allows each of the new cells to get one copy of each chromosome. When the microtubules are growing, a molecule called guanosine triphosphate (or GTP) is attached to the proteins at the end of the filament. This acts like a cap and protects the microtubule from shrinking. Later a chemical reaction converts GTP into GDP (short for guanosine diphosphate). Without the protective GTP cap, the microtubule quickly shrinks. At the same time, the proteins that make up the microtubule also change shape. In the microtubule, the proteins adopt a straight shape when GTP is attached. The proteins favor a different shape in the microtubule when GDP is attached. However, it is unclear if or how these shape changes contribute to how a microtubule grows or shrinks. Geyer et al. now show how this shape shifting can influence microtubule shrinking, by first identifying a mutation in yeast microtubule proteins that cause the proteins to remain straight even when GDP is attached. Next, powerful microscopes were used to make time-lapse videos of the mutated microtubules. This allowed Geyer et al. to observe how the mutated microtubules behaved and compare this to the behavior of normal microtubules. The experiments revealed that the mutated microtubules were less likely to begin shrinking than typical microtubules. The mutated microtubules also shrunk more slowly. These findings indicate that the shape changes control the speed of shrinking and frequency of entering the shrinking phase. These new details about the control of microtubule growth and shrinkage may help scientists studying how cell division happens in both healthy and cancerous cells. DOI:http://dx.doi.org/10.7554/eLife.10113.002
Collapse
Affiliation(s)
- Elisabeth A Geyer
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States
| | - Alexander Burns
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States
| | - Beth A Lalonde
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Xuecheng Ye
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States
| | - Felipe-Andres Piedra
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States
| | - Tim C Huffaker
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Luke M Rice
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States
| |
Collapse
|
12
|
Ayaz P, Munyoki S, Geyer EA, Piedra FA, Vu ES, Bromberg R, Otwinowski Z, Grishin NV, Brautigam CA, Rice LM. A tethered delivery mechanism explains the catalytic action of a microtubule polymerase. eLife 2014; 3:e03069. [PMID: 25097237 PMCID: PMC4145800 DOI: 10.7554/elife.03069] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Stu2p/XMAP215 proteins are essential microtubule polymerases that use multiple αβ-tubulin-interacting TOG domains to bind microtubule plus ends and catalyze fast microtubule growth. We report here the structure of the TOG2 domain from Stu2p bound to yeast αβ-tubulin. Like TOG1, TOG2 binds selectively to a fully 'curved' conformation of αβ-tubulin, incompatible with a microtubule lattice. We also show that TOG1-TOG2 binds non-cooperatively to two αβ-tubulins. Preferential interactions between TOGs and fully curved αβ-tubulin that cannot exist elsewhere in the microtubule explain how these polymerases localize to the extreme microtubule end. We propose that these polymerases promote elongation because their linked TOG domains concentrate unpolymerized αβ-tubulin near curved subunits already bound at the microtubule end. This tethering model can explain catalyst-like behavior and also predicts that the polymerase action changes the configuration of the microtubule end.
Collapse
Affiliation(s)
- Pelin Ayaz
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Sarah Munyoki
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Elisabeth A Geyer
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Felipe-Andrés Piedra
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Emily S Vu
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Raquel Bromberg
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Zbyszek Otwinowski
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Nick V Grishin
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States Howard Hughes Medical Institute, UT Southwestern Medical Center, Dallas, United States
| | - Chad A Brautigam
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States
| | - Luke M Rice
- Department of Biophysics, UT Southwestern Medical Center, Dallas, United States Department of Biochemistry, UT Southwestern Medical Center, Dallas, United States
| |
Collapse
|
13
|
Frank AL, Taber LH, Glezen WP, Geyer EA, McIlwain S, Paredes A. Influenza B virus infections in the community and the family. The epidemics of 1976-1977 and 1979-1980 in Houston, Texas. Am J Epidemiol 1983; 118:313-25. [PMID: 6613976 DOI: 10.1093/oxfordjournals.aje.a113638] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Influenza B virus epidemics occurred in Houston, Texas, in 1976-1977 and 1979-1980. Among families with young children followed longitudinally in the Houston Family Study, 112 infections were detected during 511 person-years of observation. The infection rates for the two epidemics were similar--24 per cent and 20 per cent--although the two epidemics differed greatly in the community. The first epidemic was much more intense with a mid-winter peak that produced school absentee rates above 12 per cent for four consecutive weeks. The indolent epidemic of 1979-1980 smoldered from late September to mid-April with a peak during the second week of March for which school absenteeism did not exceed 8 per cent. In the Houston Family Study population, the combined infection rate for the two outbreaks was highest at 35 per 100 person-years for school children aged 6-19 years. Preschool children aged 7 months-5 years and adults had infection rates of 31 and 16 per 100 person-years, respectively. Preexisting neutralizing antibody titers greater than or equal to 3.5 log2 protected against influenza B infection and illness. Preschool children above 6 months of age, school age children, and parents introduced infection into the family at rates of 15, 15, and 9 per 100 person-years, respectively. Three second introductions were observed. The secondary infection rate was highest among school aged children at 61 per 100 persons at risk.
Collapse
|