title: Two functionally distinct kinetochore pools of BubR1 ensure accurate chromosome segregation.
abstract: The BubR1/Bub3 complex is an important regulator of chromosome segregation as it facilitates proper kinetochore-microtubule interactions and is also an essential component of the spindle assembly checkpoint (SAC). Whether BubR1/Bub3 localization to kinetochores in human cells stimulates SAC signalling or only contributes to kinetochore-microtubule interactions is debated. Here we show that two distinct pools of BubR1/Bub3 exist at kinetochores and we uncouple these with defined BubR1/Bub3 mutants to address their function. The major kinetochore pool of BubR1/Bub3 is dependent on direct Bub1/Bub3 binding and is required for chromosome alignment but not for the SAC. A distinct pool of BubR1/Bub3 localizes by directly binding to phosphorylated MELT repeats on the outer kinetochore protein KNL1. When we prevent the direct binding of BubR1/Bub3 to KNL1 the checkpoint is weakened because BubR1/Bub3 is not incorporated into checkpoint complexes efficiently. In conclusion, kinetochore localization supports both known functions of BubR1/Bub3.
authors.affiliation: The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhang
authors.affiliation: The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
authors.forename: Blanca Lopez
authors.initials: BL
authors.lastname: Mendez
authors.affiliation: The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
authors.forename: Garry G
authors.initials: GG
authors.lastname: Sedgwick
authors.affiliation: The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Nilsson
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism; D020090:Chromosome Segregation; D064112:Clustered Regularly Interspaced Short Palindromic Repeats; D005822:Genetic Vectors; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D008870:Microtubules; D010766:Phosphorylation; D000075223:Poly-ADP-Ribose Binding Proteins / Q000378:metabolism; D060066:Protein Interaction Maps; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins
chemical_list: C489444:BUB3 protein, human; D018797:Cell Cycle Proteins; C472643:Knl1 protein, human; D008869:Microtubule-Associated Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D011994:Recombinant Proteins; C584277:BUB1 protein, human; D017346:Protein Serine-Threonine Kinases