TY - JOUR
T1 - BubR1 N Terminus Acts as a Soluble Inhibitor of Cyclin B Degradation by APC/CCdc20 in Interphase
AU - Malureanu, Liviu A.
AU - Jeganathan, Karthik B.
AU - Hamada, Masakazu
AU - Wasilewski, Lisa
AU - Davenport, James
AU - van Deursen, Jan M.
N1 - Funding Information:
We thank members of the van Deursen lab for helpful discussions, Rick Bram, Meelad Dawlaty, Robin Ricke, Limin Liu, Darren Baker, and Paul Galardy for critically reading the manuscript, Jonathon Pines for plasmids, and Don Cleveland for antibodies. This work was supported by NIH grant CA96985 and the Ellison Medical Foundation.
PY - 2009/1/20
Y1 - 2009/1/20
N2 - BubR1 is an essential mitotic checkpoint protein with multiple functional domains. It has been implicated in mitotic checkpoint control, as an active kinase at unattached kinetochores, and as a cytosolic inhibitor of APC/CCdc20 activity, as well as in mitotic timing and stable chromosome-spindle attachment. Using BubR1-conditional knockout cells and BubR1 domain mutants, we demonstrate that the N-terminal Cdc20 binding domain of BubR1 is essential for all of these functions, whereas its C-terminal Cdc20-binding domain, Bub3-binding domain, and kinase domain are not. We find that the BubR1 N terminus binds to Cdc20 in a KEN box-dependent manner to inhibit APC/C activity in interphase, thereby allowing accumulation of cyclin B in G2 phase prior to mitosis onset. Together, our results suggest that kinetochore-bound BubR1 is nonessential and that soluble BubR1 functions as a pseudosubstrate inhibitor of APC/CCdc20 during interphase to prevent unscheduled degradation of specific APC/C substrates.
AB - BubR1 is an essential mitotic checkpoint protein with multiple functional domains. It has been implicated in mitotic checkpoint control, as an active kinase at unattached kinetochores, and as a cytosolic inhibitor of APC/CCdc20 activity, as well as in mitotic timing and stable chromosome-spindle attachment. Using BubR1-conditional knockout cells and BubR1 domain mutants, we demonstrate that the N-terminal Cdc20 binding domain of BubR1 is essential for all of these functions, whereas its C-terminal Cdc20-binding domain, Bub3-binding domain, and kinase domain are not. We find that the BubR1 N terminus binds to Cdc20 in a KEN box-dependent manner to inhibit APC/C activity in interphase, thereby allowing accumulation of cyclin B in G2 phase prior to mitosis onset. Together, our results suggest that kinetochore-bound BubR1 is nonessential and that soluble BubR1 functions as a pseudosubstrate inhibitor of APC/CCdc20 during interphase to prevent unscheduled degradation of specific APC/C substrates.
KW - CELLBIO
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U2 - 10.1016/j.devcel.2008.11.004
DO - 10.1016/j.devcel.2008.11.004
M3 - Article
C2 - 19154723
AN - SCOPUS:58149466578
SN - 1534-5807
VL - 16
SP - 118
EP - 131
JO - Developmental Cell
JF - Developmental Cell
IS - 1
ER -