The Dam1/DASH complex is required for the retrieval of unclustered kinetochores in fission yeast

Franco, Alejandro; Meadows, John C.; Millar, Jonathan

doi:10.1242/jcs.013698

Cited by 50 publications

(64 citation statements)

References 45 publications

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“…1, step 2, end-on pulling; Fig. 2b; Franco et al 2007;Tanaka et al 2007;Gachet et al 2008). Biochemical reconstitution revealed that about 16 Dam1 complexes oligomerize and form a ring that encircles a microtubule ( Fig.…”

Section: Interface Of Kinetochore Microtubule Interaction: the Ndc80 mentioning

confidence: 99%

“…The lateral microtubule surface, known as the lattice, provides much larger contact surface, compared with microtubule tips, thus, contributing to an efficient first encounter with kinetochores. The capture of microtubule lattice by kinetochores was initially discovered in newt lung cells (Hayden et al 1990;Rieder and Alexander 1990) and subsequently found in budding yeast and fission yeast (Tanaka et al 2005a;Franco et al 2007;Gachet et al 2008); therefore, this mode of the capture is widely conserved among eukaryotic cells.…”

Section: Introductionmentioning

confidence: 99%

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Bi-orienting chromosomes: acrobatics on the mitotic spindle

Tanaka

2008

Chromosoma

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To maintain their genetic integrity, eukaryotic cells must segregate their chromosomes properly to opposite poles during mitosis. This process mainly depends on the forces generated by microtubules that attach to kinetochores. During prometaphase, kinetochores initially interact with a single microtubule that extends from a spindle pole and then move towards a spindle pole. Subsequently, microtubules that extend from the other spindle pole also interact with kinetochores and, eventually, each sister kinetochore attaches to microtubules that extend from opposite poles (sister kinetochore bi-orientation). If sister kinetochores interact with microtubules in wrong orientation, this must be corrected before the onset of anaphase. Here, I discuss the processes leading to biorientation and the mechanisms ensuring this pivotal state that is required for proper chromosome segregation.

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Section: Interface Of Kinetochore Microtubule Interaction: the Ndc80 mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bi-orienting chromosomes: acrobatics on the mitotic spindle

Tanaka

2008

Chromosoma

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“…Kinetochores include MT-dependent motors and several protein complexes that lack motor activity but can still bind to a MT wall or end. These nonmotor complexes too may be important for chromosome motion, because depolymerizing MTs can generate enough force to move chromosomes without the help of motors, both in vivo and in vitro (4)(5)(6)(7).…”

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confidence: 99%

Different assemblies of the DAM1 complex follow shortening microtubules by distinct mechanisms

Grishchuk

Spiridonov

Volkov

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

135

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Mitotic chromosomes segregate at the ends of shortening spindle microtubules (MTs). In budding yeast, the Dam1 multiprotein complex supports this dynamic attachment, thereby contributing to accurate chromosome segregation. Purified Dam1 will track the end of a depolymerizing MT and can couple it to microbead transport in vitro. The processivity of such motions has been thought to depend on rings that the Dam1 complex can form around MTs, but the possibility that alternative coupling geometries contribute to these motilities has not been considered. Here, we demonstrate that both rings and nonencircling Dam1 oligomers can track MT ends and enable processive cargo movement in vitro. The coupling properties of these two assemblies are, however, quite different, so each may make a distinct contribution to chromosome motility.chromosome motions ͉ kinetochore-microtubule interactions ͉ microtubule end tracking M itotic chromosomes are attached to spindle fibers by a multiprotein complex, the kinetochore (1-3). Kinetochores bind strongly to the plus ends of spindle microtubules (MTs), but tubulin subunits can still be added or lost from these MT ends as the chromosomes move. Kinetochores are also sites where forces can be generated to move chromosomes either toward or away from the pole that a kinetochore faces, so this interface provides multiple important mitotic functions. Kinetochores include MT-dependent motors and several protein complexes that lack motor activity but can still bind to a MT wall or end. These nonmotor complexes too may be important for chromosome motion, because depolymerizing MTs can generate enough force to move chromosomes without the help of motors, both in vivo and in vitro (4-7).The mechanism by which a kinetochore is coupled to the end of a shortening or lengthening MT is still unknown, but a 10-subunit protein complex from budding yeast kinetochores, called Dam1 or DASH, is important for chromosome-spindle attachments and spindle integrity in this organism (3). Purified Dam1 heterodecamers assemble around MTs into rings of 16-25 subunits (8, 9). At higher protein concentrations, both multiple rings and helices of Dam1 will form (10, 11).In yeast spindles, Dam1 is found primarily at kinetochores, although some of it associates with spindle MTs (12). A careful estimate of the number of Dam1 subunits at metaphase kinetochores in budding yeast gave 16-20 heterodecamers (12), enough to form a single ring. The behavior of kinetochore-associated Dam1 fluorescence suggests that these subunits are stably attached to kinetochore MTs, showing little or no turnover. However, a second population of Dam1, which is dimly localized to spindle MTs, shows faster turnover, indicating the presence of a dynamic pool of complexes (12).Oligomers of Dam1 can travel with a shortening MT in vitro (8), suggesting that this complex may be the primary MT-chromosome coupler in yeast. A bead coated with Dam1 will also associate with a MT in vitro and follow its end during either assembly or disassembly (13, 14), proper...

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“…20). Similar to ScDam1, SpDam1 is localized at kinetochores as well as on the spindle and the intranuclear MT (20)(21)(22), and functions in coupling kinetochores to MTs (22)(23)(24). Using quantitative fluorescence microscopy, it was determined that on average only seven to eight copies of SpDam1 per kinetochore were found (25).…”

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confidence: 99%

A non-ring-like form of the Dam1 complex modulates microtubule dynamics in fission yeast

Gao

Courthéoux

Gachet

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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The Dam1 complex is a kinetochore component that couples chromosomes to the dynamic ends of kinetochore microtubules (kMTs). Work in the budding yeast Saccharomyces cerevisiae has shown that the Dam1 complex forms a 16-unit ring encircling and tracking the tip of a MT in vitro, consistent with its cellular function as a coupler. Dam1 also forms smaller, nonring patches in vitro that track the dynamic ends of MTs. However, the identity of Dam1’s functional form in vivo remains unknown. Here we report a comprehensive in vivo characterization of Dam1 in the fission yeast Schizosaccharomyces pombe . In addition to their dense localizations on kinetochores and spindle MTs during mitosis, we identify that Dam1 is also localized onto cytoplasmic MTs as discrete spots in interphase, providing the unique opportunity to analyze Dam1 oligomers at the single-particle resolution in live cells. Such analysis shows that each oligomer contains one to five copies of Dam1, and is able to “switch-rail” while moving along MTs, precluding the possibility of a 16-unit encircling structure. Dam1 patches track the plus ends of the shortening, but not the elongating, MTs and retard MT depolymerization. Together with Mal3, the EB1-like MT-interacting protein, cytoplasmic Dam1 plays an important role in maintaining proper cell shape. In mitosis, kinetochore-associated Dam1 appears to facilitate kMT depolymerization. Together, our findings suggest that patches, instead of rings, are the physiologically functional forms of Dam1 in pombe. Our findings help establish the benchmark parameters of the Dam1 coupler and elucidate the mechanism of its functions.

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The Dam1/DASH complex is required for the retrieval of unclustered kinetochores in fission yeast

Cited by 50 publications

References 45 publications

Bi-orienting chromosomes: acrobatics on the mitotic spindle

Bi-orienting chromosomes: acrobatics on the mitotic spindle

Different assemblies of the DAM1 complex follow shortening microtubules by distinct mechanisms

A non-ring-like form of the Dam1 complex modulates microtubule dynamics in fission yeast

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