 |
PDBsum entry 3e7e
|
|
|
|
References listed in PDB file
|
 |
|
Key reference
|
|
|
Title
|
|
Structure and substrate recruitment of the human spindle checkpoint kinase bub1.
|
|
|
Authors
|
|
J.Kang,
M.Yang,
B.Li,
W.Qi,
C.Zhang,
K.M.Shokat,
D.R.Tomchick,
M.Machius,
H.Yu.
|
|
|
Ref.
|
|
Mol Cell, 2008,
32,
394-405.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
In mitosis, the spindle checkpoint detects a single unattached kinetochore,
inhibits the anaphase-promoting complex or cyclosome (APC/C), and prevents
premature sister chromatid separation. The checkpoint kinase Bub1 contributes to
checkpoint sensitivity through phosphorylating the APC/C activator, Cdc20, and
inhibiting APC/C catalytically. We report here the crystal structure of the
kinase domain of Bub1, revealing the requirement of an N-terminal extension for
its kinase activity. Though the activation segment of Bub1 is ordered and has
structural features indicative of active kinases, the C-terminal portion of this
segment sterically restricts substrate access to the active site. Bub1 uses
docking motifs, so-called KEN boxes, outside its kinase domain to recruit Cdc20,
one of two known KEN box receptors. The KEN boxes of Bub1 are required for the
spindle checkpoint in human cells. Therefore, its unusual active-site
conformation and mode of substrate recruitment suggest that Bub1 has an
exquisitely tuned specificity for Cdc20.
|
|
|
|
|
|
|
|
Figure 1.
Figure 1. Structure and Inhibitor of the Extended Kinase
Domain of Bub1
(A) Domain architecture of human Bub1. TPR,
tetratricopeptide repeat; GLEBS, Gle2-binding sequence; KEN,
lysine-glutamate-asparagine.
(B) Ribbon drawing of the
crystal structure of the extended kinase domain of Bub1. The
N-terminal extension is colored yellow. The substrate-binding
P+1 loop is shown in green, while the rest of the activation
segment is in blue. The catalytic loop is shown in red. ATP is
shown as sticks. The Mg^2+ ion is shown as a gray sphere. The N
and C termini are indicated. All structure figures were
generated with PyMOL (http://pymol.sourceforge.net/).
(C)
The ATP-binding site of Bub1. ATP is shown as sticks. The extra
pocket is indicated.
(D) The chemical structure of
2OH-BNPP1.
(E) Determination of the IC[50] values of
2OH-BNPP1 against Aurora B, p38, Bub1C, and Bub1.
|
|
Figure 2.
Figure 2. The N-Terminal Extension Activates Bub1 with a
Cyclin-like Mechanism
Ribbon diagrams of Bub1C, Cdk2, and
Cdk2-Cyclin A. The N and C termini are indicated. The color
schemes are as described in Figure 1B except that αC is colored
magenta. The ATP-binding lysine residues and the conserved
glutamate residues in αC are shown as sticks. Cyclin A is shown
in yellow.
|
|
|
|
|
|
The above figures are
reprinted
from an Open Access publication published by Cell Press:
Mol Cell
(2008,
32,
394-405)
copyright 2008.
|
|
|
|
|
|
|
