Rings, bracelets, sleeves, and chevrons: new structures of kinetochore proteins

Davis, Trisha N.; Wordeman, Linda

doi:10.1016/j.tcb.2007.08.001

Cited by 26 publications

(23 citation statements)

References 43 publications

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“…Therefore, for this coupling to be biologically successful, there must be some additional mechanism that ensures its attachment. For example, the stability of Dam1 ring attachment might be augmented by other kinetochore proteins and/or proteins that bind MT plus ends (40). Such interactions are possible, but their effects on ring motility are speculative.…”

Section: Discussionmentioning

confidence: 99%

In search of an optimal ring to couple microtubule depolymerization to processive chromosome motions

Efremov

Grishchuk

McIntosh

et al. 2007

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

128

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Mitotic chromosome motions are driven by microtubules (MTs) and associated proteins that couple kinetochores to MT ends. A good coupler should ensure a high stability of attachment, even when the chromosome changes direction or experiences a large opposing force. The optimal coupler is also expected to be efficient in converting the energy of MT depolymerization into chromosome motility. As was shown years ago, a ''sleeve''-based, chromosomeassociated structure could, in principle, couple MT dynamics to chromosome motion. A recently identified kinetochore complex from yeast, the ''Dam1'' or ''DASH'' complex, may function as an encircling coupler in vivo. Some features of the Dam1 ring differ from those of the ''sleeve,'' but whether these differences are significant has not been examined. Here, we analyze theoretically the biomechanical properties of encircling couplers that have properties of the Dam1/DASH complex, such as its large diameter and inward-directed extensions. We demonstrate that, if the coupler is modeled as a wide ring with links that bind the MT wall, its optimal performance is achieved when the linkers are flexible and their binding to tubulin dimers is strong. The diffusive movement of such a coupler is limited, but MT depolymerization can drive its motion via a ''forced walk,'' whose features differ significantly from those of the mechanisms based on biased diffusion. Our analysis identifies key experimental parameters whose values should determine whether the Dam1/DASH ring moves via diffusion or a forced walk.biased diffusion ͉ kinetochore ͉ mathematical model ͉ power stroke ͉ energy-transducing coupler C hromosome segregation during cell division depends on the activities of microtubules (MTs), which are cylindrical arrangements of 13 linear polymers of ␣␤-tubulin dimers called protofilaments (PFs) (1). Tubulin complexed with GTP elongates PF ends, but this GTP is hydrolyzed soon after dimers have added (2). The preferred conformation of the GDP dimers is more bent, so the PFs tend to curve (3, 4). In a growing MT, this tendency is counteracted by a relatively straight ''GTP cap,'' but if the terminal layers are lost, the PFs are no longer restrained (1, 2). As they splay out, the dimers dissociate from their longitudinal neighbors, and the MT shortens (5, 6). Consequently, the ends of depolymerizing MTs in vitro and in vivo display curved PFs (3,[5][6][7][8][9]. Representative images of kinetochore MTs are shown in Fig. 1A; the length of PF flares in anaphase mammalian cells is 53 Ϯ 7 nm, n ϭ 368 PFs (J.R.M., E.L.G., A.E., K. Zhudenkov, M. Morphew, et al., unpublished work).It is well documented that MTs can move chromosomes or microbeads that associate with their shortening ends (9-15). Several hypotheses have explained these force-transducing attachments with the help of a coupler that encircles the MT (16-18). Movement in these models is driven ultimately by the energy released during hydrolysis of tubulin-associated GTP (Ϸ12 k B T; k B , Boltzmann constant). However, the design of a ...

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Section: Discussionmentioning

confidence: 99%

In search of an optimal ring to couple microtubule depolymerization to processive chromosome motions

Efremov

Grishchuk

McIntosh

et al. 2007

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

128

View full text Add to dashboard Cite

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“…However, during the process of cold shock and kinetochore retrieval, we found that Dam1 and Klp2 can decorate the INMs either as single or multiple dots and always colocalize with the kinetochore during its retrieval. Because these dots could either be the plus ends of microtubules within a bundle or other structures along the microtubule (Davis and Wordeman, 2007), we cannot at this time discriminate between these different hypotheses (i.e., kinetochore retrieval by surfing along the INM and kinetochore retrieval by selective microtubule shrinkage within the INM).…”

Section: Discussionmentioning

confidence: 99%

Sister Kinetochore Recapture in Fission Yeast Occurs by Two Distinct Mechanisms, Both Requiring Dam1 and Klp2

Gachet

Reyes

Courthéoux

et al. 2008

MBoC

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In eukaryotic cells, proper formation of the spindle is necessary for successful cell division. We have studied chromosome recapture in the fission yeast Schizosaccharomyces pombe. We show by live cell analysis that lost kinetochores interact laterally with intranuclear microtubules (INMs) and that both microtubule depolymerization (end-on pulling) and minus-end-directed movement (microtubule sliding) contribute to chromosome retrieval to the spindle pole body (SPB). We find that the minus-end-directed motor Klp2 colocalizes with the kinetochore during its transport to the SPB and contributes to the effectiveness of retrieval by affecting both end-on pulling and lateral sliding. Furthermore, we provide in vivo evidence that Dam1, a component of the DASH complex, also colocalizes with the kinetochore during its transport and is essential for its retrieval by either of these mechanisms. Finally, we find that the position of the unattached kinetochore correlates with the size and orientation of the INMs, suggesting that chromosome recapture may not be a random process.

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“…Two independent screens (Newman et al 2000;Wong et al 2007) have found Zip1p to be physically interacting with two different components, Nuf2p and Spc24p, of the outer kinetochore complex Ndc80. The Ndc80 complex plays a vital role in chromosome segregation and mediates interaction between the kinetochores and the spindle microtubules during chromosome movement (reviewed by Kotwaliwale and Biggins 2006;Ciferri et al 2007;Davis and Wordeman 2007;Westermann et al 2007;Tanaka and Desai 2008). Zip1p's multiple interaction with this kinetochore complex raised the possibility that two molecules of Zip1p could connect two sister kinetochores in a manner analogous to the way they connect two lateral elements in the SC (fi gure 3B), and that this Zip1p-mediated interaction between sister kinetochores might promote mono-orientation in meiosis-I.…”

Section: Role Of the Synaptonemal Complex In Monopolar Orientationmentioning

confidence: 99%

Complex regulation of sister kinetochore orientation in meiosis-I

Bardhan¹

2010

J Biosci

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Kinetochores mediate chromosome movement during cell division by interacting with the spindle microtubules. Sexual reproduction necessitates the daunting task of reducing ploidy (number of chromosome sets) in the gametes, which depends upon the specialized properties of meiosis. Kinetochores have a central role in the reduction process. In this review, we discuss the complexity of this role of kinetochores in meiosis-I.

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Rings, bracelets, sleeves, and chevrons: new structures of kinetochore proteins

Cited by 26 publications

References 43 publications

In search of an optimal ring to couple microtubule depolymerization to processive chromosome motions

In search of an optimal ring to couple microtubule depolymerization to processive chromosome motions

Sister Kinetochore Recapture in Fission Yeast Occurs by Two Distinct Mechanisms, Both Requiring Dam1 and Klp2

Complex regulation of sister kinetochore orientation in meiosis-I

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