The Role of the Kinesin-13 Neck in Microtubule Depolymerization

Moores, Carolyn A.; Cooper, Jeremy; Wagenbach, Mike; Ovechkina, Yulia; Wordeman, Linda; Milligan, Ronald A.

doi:10.4161/cc.5.16.3134

Cited by 41 publications

(36 citation statements)

References 22 publications

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“…The key step in the kinesin-13 MT-depolymerisation mechanism occurs as ATP binds, demonstrated by the unpeeling of stabilised MTs in the presence (and only in the presence) of the non-hydrolysable ATP analogue, AMPPNP (Desai et al, 1999;Moores et al, 2002;Shipley et al, 2004;Moores et al, 2006a). These bent tubulin structures form because the kinesin-13 motor is trapped in a pre-hydrolysis state that actively bends the underlying terminal tubulin.…”

Section: The Depolymerisation Mechanismmentioning

confidence: 99%

Lucky 13 - microtubule depolymerisation by kinesin-13 motors

Moores

Milligan

2006

Journal of Cell Science

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The kinesin-13 class of motors catalyses microtubule depolymerisation by bending tubulins at microtubule ends. Depolymerisation activity is intrinsic to the kinesin-13 motor core but the activity of the core alone is very low compared with that of constructs that also contain a conserved neck sequence. The full-length dimeric motor is an efficient depolymeriser and also diffuses along the microtubule lattice, which helps it to find microtubule ends. Current evidence supports the idea of a generic mechanism for kinesin-13-catalysed depolymerisation. However, the activity of kinesin-13 motors is precisely localised and regulated in vivo to enable a wide range of cellular roles. The proteins are involved in global control of microtubule dynamics. They also localise to mitotic and meiotic spindles, where they contribute to formation and maintenance of spindle bipolarity, chromosomal congression, attachment correction and chromatid separation. In interphase cells, intricate and subtle mechanisms appear to allow kinesin-13 motors to act on specific populations of microtubules. Such carefully controlled localisation and regulation makes these kinesins efficient, multi-tasking molecular motors.

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Section: The Depolymerisation Mechanismmentioning

confidence: 99%

Lucky 13 - microtubule depolymerisation by kinesin-13 motors

Moores

Milligan

2006

Journal of Cell Science

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“…In dynamic MTs, this curved protofilament within the MT is unstable and is thought to cause the MT polymer to depolymerize (Desai and Mitchison, 1997;Nogales, 2000). For in vitro-stabilized MTs, it is unclear whether MCAK depolymerizes MTs by removing individual tubulin dimers or tubulin oligomers (Desai et al, 1999b;Hunter et al, 2003;Moores et al, 2006;Tan et al, 2006), but it is thought that the ultimate end product from MCAK-induced MT depolymerization is tubulin heterodimer (Desai et al, 1999b). MCAK may processively depolymerize MTs by a mechanism that involves one-dimensional (1-D) diffusion of MCAK along the MT lattice or by the accumulation of tubulin-MCAK rings at the MT end (Hunter et al, 2003;Helenius et al, 2006;Tan et al, 2006), but it remains unclear how these mechanisms are utilized during depolymerization of dynamic MTs and how the different domains of MCAK contribute to this depolymerization activity.…”

Section: Introductionmentioning

confidence: 99%

The Interplay of the N- and C-Terminal Domains of MCAK Control Microtubule Depolymerization Activity and Spindle Assembly

Ems-McClung

Hertzer

Zhang

et al. 2007

MBoC

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Spindle assembly and accurate chromosome segregation require the proper regulation of microtubule dynamics. MCAK, a Kinesin-13, catalytically depolymerizes microtubules, regulates physiological microtubule dynamics, and is the major catastrophe factor in egg extracts. Purified GFP-tagged MCAK domain mutants were assayed to address how the different MCAK domains contribute to in vitro microtubule depolymerization activity and physiological spindle assembly activity in egg extracts. Our biochemical results demonstrate that both the neck and the C-terminal domain are necessary for robust in vitro microtubule depolymerization activity. In particular, the neck is essential for microtubule end binding, and the C-terminal domain is essential for tight microtubule binding in the presence of excess tubulin heterodimer. Our physiological results illustrate that the N-terminal domain is essential for regulating microtubule dynamics, stimulating spindle bipolarity, and kinetochore targeting; whereas the C-terminal domain is necessary for robust microtubule depolymerization activity, limiting spindle bipolarity, and enhancing kinetochore targeting. Unexpectedly, robust MCAK microtubule (MT) depolymerization activity is not needed for sperm-induced spindle assembly. However, high activity is necessary for proper physiological MT dynamics as assayed by Ran-induced aster assembly. We propose that MCAK activity is spatially controlled by an interplay between the N-and C-terminal domains during spindle assembly. INTRODUCTIONBipolar spindle assembly is essential for the faithful segregation of chromosomes into two daughter nuclei. Defects in this process are often associated with aneuploidy, which can lead to cancer or birth defects. The bipolar spindle is composed of a dynamic array of microtubules (MTs) and their associated proteins, including various MT-associated proteins and motor proteins, which are essential for proper spindle assembly (Gadde and Heald, 2004;Mogilner et al., 2006). Proper MT dynamics are highly regulated during the transition between interphase and mitosis, and many regulators of MT dynamics are critical for proper spindle assembly both in cells and in Xenopus laevis egg extracts (KlineSmith and Walczak, 2004). In egg extracts, spindle assembly is dominated by chromatin-mediated MT nucleation and organization (Sawin and Mitchison, 1991). During chromatin-mediated spindle assembly, randomly nucleated MTs around chromatin become organized into an astral array that leads to the formation of a bipolar spindle due to the generation of anti-parallel overlapping MTs that are extended and focused into poles by molecular motors and MT-associated proteins (Walczak et al., 1997(Walczak et al., , 1998Sharp et al., 2000;Gaetz and Kapoor, 2004;Mitchison et al., 2004Mitchison et al., , 2005Koffa et al., 2006). In addition to relying on molecular motors to organize and slide MTs, bipolarity also depends on the regulation of proper physiological MT dynamics by depolymerizing proteins that include depolymerizing kinesins and...

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“…In contrast, TOG domain-containing proteins, such as XMAP215, promote MT growth and have been suggested to act as MT "polymerases" (10,11). Conversely, kinesin-13s [e.g., mitotic centromere-associated kinesin (MCAK) from hamster] increase instability of MT ends, leading to increased catastrophe frequency (12,13). Thus, regulation of these and other +TIPs can dramatically affect the stability and turnover of the MT network (14,15).…”

mentioning

confidence: 99%

Regulation of microtubule minus-end dynamics by CAMSAPs and Patronin

Hendershott

Vale

2014

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

157

184

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The microtubule (MT) cytoskeleton plays an essential role in mitosis, intracellular transport, cell shape, and cell migration. The assembly and disassembly of MTs, which can occur through the addition or loss of subunits at the plus-or minus-ends of the polymer, is essential for MTs to carry out their biological functions. A variety of proteins act on MT ends to regulate their dynamics, including a recently described family of MT minus-end binding proteins called calmodulin-regulated spectrin-associated protein (CAMSAP)/Patronin/Nezha. Patronin, the single member of this family in Drosophila, was previously shown to stabilize MT minusends against depolymerization in vitro and in vivo. Here, we show that all three mammalian CAMSAP family members also bind specifically to MT minus-ends and protect them against kinesin-13-induced depolymerization. However, these proteins differ in their abilities to suppress tubulin addition at minus-ends and to dissociate from MTs. CAMSAP1 does not interfere with polymerization and tracks along growing minus-ends. CAMSAP2 and CAMSAP3 decrease the rate of tubulin incorporation and remain bound, thereby creating stretches of decorated MT minus-ends. By using truncation analysis, we find that somewhat different minimal domains of CAMSAP and Patronin are involved in minus-end localization. However, we find that, in both cases, a highly conserved C-terminal domain and a more variable central domain cooperate to suppress minus-end dynamics in vitro and that both regions are required to stabilize minus-ends in Drosophila S2 cells. These results show that members of the CAMSAP/Patronin family all localize to and protect minus-ends but have evolved distinct effects on MT dynamics.tubulin polymerization | cytoskeletal regulation | TIRF microscopy M icrotubules (MTs) are cellular polymers that are important for a variety of functions, including cargo transport and mitotic spindle formation. MTs are composed of dimers of α-and β-tubulin that assemble head-to-tail, creating a polar protofilament. Protofilaments then assemble laterally to form the canonical 13-protofilament MT structure, with β-tubulin exposed at fast-growing plus-ends and α-tubulin exposed at slow-growing minus-ends (1). MTs exhibit an intriguing property termed "dynamic instability," whereby the polymer can abruptly switch between episodes of net growth and shrinkage (2). The rates of growth and shrinkage as well as the frequency of transitions between these two states are regulated by numerous MT-associated proteins, many of which bind to the ends of the polymer (3, 4).The dynamics of MT plus-ends are regulated by a well-characterized network of plus-end tracking proteins (+TIPs) (5). End-binding proteins recognize a tubulin conformation unique to the growing ends of MTs and can affect the dynamics of plusends by intrinsically altering the structure of the MT end (6-8) as well as recruiting other interacting proteins (9). In contrast, TOG domain-containing proteins, such as XMAP215, promote MT growth and have been suggested ...

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The Role of the Kinesin-13 Neck in Microtubule Depolymerization

Cited by 41 publications

References 22 publications

Lucky 13 - microtubule depolymerisation by kinesin-13 motors

Lucky 13 - microtubule depolymerisation by kinesin-13 motors

The Interplay of the N- and C-Terminal Domains of MCAK Control Microtubule Depolymerization Activity and Spindle Assembly

Regulation of microtubule minus-end dynamics by CAMSAPs and Patronin

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