Abstract
Kinetochores, multi-subunit complexes that assemble at the interface with centromeres, bind spindle microtubules to ensure faithful delivery of chromosomes during cell division. The configuration and function of the kinetochore-centromere interface is poorly understood. We report that a protein at this interface, CENP-M, is structurally and evolutionarily related to small GTPases but is incapable of GTP-binding and conformational switching. We show that CENP-M is crucially required for the assembly and stability of a tetramer also comprising CENP-I, CENP-H, and CENP-K, the HIKM complex, which we extensively characterize through a combination of structural, biochemical, and cell biological approaches. A point mutant affecting the CENP-M/CENP-I interaction hampers kinetochore assembly and chromosome alignment and prevents kinetochore recruitment of the CENP-T/W complex, questioning a role of CENP-T/W as founder of an independent axis of kinetochore assembly. Our studies identify a single pathway having CENP-C as founder, and CENP-H/I/K/M and CENP-T/W as CENP-C-dependent followers.DOI: http://dx.doi.org/10.7554/eLife.02978.001.
Highlights
Mitosis creates two genetically identical daughter cells through the equal segregation of sister chromatids
In mitotic HeLa cells, depletion of CENP-M prevented chromosome alignment at the metaphase plate to a comparable degree to that caused by Hesperadin, a small-molecule competitive inhibitor of Aurora B kinase, whose activity is crucially required for chromosome alignment (Hauf et al, 2003; Figure 1F)
The CENP-T458–C/W complex was sufficient for an CENP-M was initially identified for its high expression in proliferating cells, and named PANE1, for proliferation associated nuclear element 1 (Bierie et al, 2004)
Summary
Mitosis creates two genetically identical daughter cells through the equal segregation of sister chromatids. On the other hand, aims to halve the genetic content of a mother cell. Chromosome segregation is executed by molecular machinery that is largely conserved in the evolution of eukaryotes. Kinetochores are essential elements of such machinery (Santaguida and Musacchio, 2009; Westermann and Schleiffer, 2013). They are biochemically complex structures, which contain multiple copies of approximately 30 core subunits, in turn contributing to recruit many additional regulatory proteins (Figure 1A). Kinetochores can be viewed as layered structures, whose inner and outer layers directly contact centromeric chromatin and spindle microtubules, respectively
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
