The C-terminal helix of BubR1 is essential for CENP-E-dependent chromosome alignment

Abstract

During cell division, misaligned chromosomes are captured and aligned by motors before their segregation. The CENP-E motor is recruited to polar unattached kinetochores to facilitate chromosome alignment. The spindle checkpoint protein BubR1 (also known as BUB1B) has been reported as a CENP-E interacting partner, but the extent to which BubR1 contributes to CENP-E localization at kinetochores has remained controversial. Here we define the molecular determinants that specify the interaction between BubR1 and CENP-E. The basic C-terminal helix of BubR1 is necessary but not sufficient for CENP-E interaction, and a minimal key acidic patch on the kinetochore-targeting domain of CENP-E is also essential. We then demonstrate that BubR1 is required for the recruitment of CENP-E to kinetochores to facilitate chromosome alignment. This BubR1–CENP-E axis is critical for alignment of chromosomes that have failed to congress through other pathways and recapitulates the major known function of CENP-E. Overall, our studies define the molecular basis and the function for CENP-E recruitment to BubR1 at kinetochores during mammalian mitosis.This article has an associated First Person interview with the first author of the paper.

Transcriptomic Changes Following Partial Depletion of CENP-E in Normal Human Fibroblasts

“…Firstly, CENP-E is a plus-end directed kinesin-7 motor bound to kinetochores, which has been identified as a component of the outer kinetochore [ 11 ] and has a role in the reinforcement of kn-mt binding, in the alignment to the spindle equator of mono-oriented chromosomes and in the spindle assembly checkpoint; however, how CENP-E is recruited in kinetochores is still debated. Recent works confirmed the previous observation that BubR1 is responsible for the initial recruitment of CENP-E in kinetochores [ 12 ], although other BubR1-indipendent mechanisms are involved in recruiting CENP-E in unattached kinetochores [ 13 ]. The role of CENP-E in ensuring stable kn-mt capture is finely regulated by aurora kinases A and B and PP1 with a phosphorylation–dephosphorylation switch mechanism [ 14 ].…”

Inhibiting microcephaly genes as alternative to microtubule targeting agents to treat brain tumors

“…No effects on mitotic spindle assembly were observed [ 96 ]. CENPE possesses at the C-terminus a kinetochore-binding domain that allows the interaction with kinetochore proteins BUBR1, CENPF, Ndc80, and HsNUF2 [ 86 , 97 ]. Instead, an ATP-dependent microtubule-binding site is present at the N-terminus, which is used for hydrolyzing ATP to generate mechanical forces along microtubules and is essential for CENPE localization at mitotic spindles [ 98 ].…”

Physiological relevance of post-translational regulation of the spindle assembly checkpoint protein BubR1

“…Interestingly, T608 phosphorylation on BubR1 appears to be related to certain CENP-E functions. Recent results confirmed that CENP-E and BubR1 interact through a C-terminal helix within the BubR1 kinase domain which may be necessary for CENP-E recruitment to the kinetochore via BubR1 [ 61 ]. It has also been postulated that the interaction between BubR1 and CENP-E through the BubR1 kinase domain stimulates BubR1s supposed kinase activity, allowing it to phosphorylate, among other substrates, itself at T608 [ 59 ].…”

“…BubR1 and CENP-E are thought to colocalize at kinetochores prior to T608 phosphorylation [ 59 , 61 , 65 ]. The presence of kinetochore–microtubule attachment errors stimulates Aurora B activity to phosphorylate KMN proteins and CENP-E, causing destabilization of the kinetochore-microtubule attachments [ 66 , 67 ].…”