Dynamic Kinetochore Size Regulation Promotes Microtubule Capture and Chromosome Biorientation in Mitosis

Abstract

Faithful chromosome segregation depends on the ability of sister kinetochores to attach to spindle microtubules. An outer layer of the kinetochore known as the fibrous corona transiently expands in early mitosis and disassembles upon microtubule capture. Neither the functional importance nor the mechanistic basis for this are known. Here we show that the dynein adaptor Spindly and the RZZ kinetochore complex drive fibrous corona formation in a dynein-independent manner. C-terminal farnesylation and MPS1 kinase activity cause conformational changes of Spindly that promote oligomerization of RZZ:Spindly complexes into a corona-like meshwork in cells and in vitro. Concurrent with corona expansion, Spindly potentiates corona shedding by recruiting dynein via three conserved short linear motifs. Expanded, nonsheddable fibrous coronas engage in extensive, long-lived lateral microtubule interactions that persist to metaphase and result in fused sister kinetochores, formation of merotelic attachments and chromosome segregation errors in anaphase.Thus, dynamic kinetochore size regulation in mitosis is coordinated by a single, Spindly-based mechanism that promotes initial microtubule capture and subsequent correct maturation of attachments.

Cryo‐EM reveals the complex architecture of dynactin's shoulder region and pointed end

“…The adaptors fall into three families, each of which uses a different DLIC‐binding motif/domain: the EF‐hand, the Hook domain, and the CC1 box (Lee et al, 2018; Lee et al, 2020). Secondly, in CC1 box adaptors (e.g., BICD2 and BICDR1), a second motif has been identified, referred to as the CC2 box (Sacristan et al, 2018). A third motif, referred to as the Spindly box, has been identified in all three families and evidence suggests that it binds to the pointed end complex (Gama et al, 2017).…”

Mutations in the Drosophila rough deal gene affecting RZZ kinetochore function

“…The earliest observations of RZZ behaviour during mitosis led to the proposal that it was a major component of the fibrous corona [Basto et al., 2004; Williams et al., 1996], an expanded outer domain of unattached kinetochores that promotes microtubule capture. Features of the modelled structure of RZZ [Mosalaganti et al., 2017] display similarities to other proteins that can self‐assemble into networks, such as COP1 and Clathrin, and recently several groups have reported direct cell biological and biochemical evidence for the participation of RZZ and its interacting partner Spindly in the assembly of the corona in vivo and filamentous structures in vitro ([Pereira et al., 2018; Rodriguez‐Rodriguez et al., 2018; Sacristan et al., 2018], reviewed in [Suzuki and Varma, 2018]). These reports have focused particular attention on the N‐terminal domain of Rod, which appears to be necessary for kinetochore expansion.…”

“…The RZZ complex, composed of the proteins Rough‐Deal (Rod), Zw10 and Zwilch, plays a central role in the SAC [Karess, 2005]. It is an important component of the outer kinetochore and specifically the fibrous corona [Basto et al., 2004; Sacristan et al., 2018], whose expansion is believed to facilitate microtubule capture. RZZ contributes to the regulation of the SAC by helping to recruit Mad1–Mad2 and dynein along with its associated regulatory proteins to unattached kinetochores [Buffin et al., 2005; Chan et al., 2009; Gama et al., 2017; Griffis et al., 2007; Kops et al., 2005; Starr et al., 1998].…”

Regulation of Cenp-F localization to nuclear pores and kinetochores

“…This suggests that the contribution of Cenp-E to Cenp-F kinetochore localization might become detectable only upon acute microtubule depolymerization. Interestingly, while the recruitment of Cenp-F and Cenp-E to kinetochores was shown to be independent from the assembly of the Rod/Zwilch/ZW10 (RZZ) complex, the main constituents of the expandable kinetochore corona ( [44,69], Preprint [70]:) this RZZ complex is required for the assembly of Cenp-F and Cenp-E in crescent-like structures when cells are treated with nocodazole ( [69], Preprint [70]:, see also Figure 2 in [44]). Ciossani and colleagues [44] also observed that depletion of Cenp-E somehow affects Cenp-F crescent formation (detected in their Figure 2(h); A. Musacchio, personal communication).…”