Abstract
In response to misaligned sister chromatids during mitosis, the spindle checkpoint protein Mad2 inhibits the anaphase-promoting complex or cyclosome (APC/C) through binding to its mitotic activator Cdc20, thus delaying anaphase onset. Mad1, an upstream regulator of Mad2, forms a tight core complex with Mad2 and facilitates Mad2 binding to Cdc20. In the absence of its binding proteins, free Mad2 has two natively folded conformers, termed N1-Mad2/open-Mad2 (O-Mad2) and N2-Mad2/closed Mad2 (C-Mad2), with C-Mad2 being more active in APC/C Cdc20 inhibition. Here, we show that whereas O-Mad2 is monomeric, C-Mad2 forms either symmetric C-Mad2-C-Mad2 (C-C) or asymmetric O-Mad2-C-Mad2 (O-C) dimers. We also report the crystal structure of the symmetric C-C Mad2 dimer, revealing the basis for the ability of unliganded C-Mad2, but not O-Mad2 or liganded C-Mad2, to form symmetric dimers. A Mad2 mutant that predominantly forms the C-C dimer is functional in vitro and in living cells. Finally, the Mad1-Mad2 core complex facilitates the conversion of O-Mad2 to C-Mad2 in vitro. Collectively, our results establish the existence of a symmetric Mad2 dimer and provide insights into Mad1-assisted conformational activation of Mad2 in the spindle checkpoint.
| Original language | English (US) |
|---|---|
| Article number | e50 |
| Pages (from-to) | 643-655 |
| Number of pages | 13 |
| Journal | PLoS Biology |
| Volume | 6 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2008 |
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ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Biochemistry, Genetics and Molecular Biology(all)
- Immunology and Microbiology(all)
- Neuroscience(all)
Cite this
Insights into Mad2 regulation in the spindle checkpoint revealed by the crystal structure of the symmetric Mad2 dimer. / Yang, Maojun; Li, Bing; Liu, Chyong Jy; Tomchick, Diana R; Machius, Mischa; Rizo-Rey, Jose; Yu, Hongtao; Luo, Xuelian.
In: PLoS Biology, Vol. 6, No. 3, e50, 03.2008, p. 643-655.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Insights into Mad2 regulation in the spindle checkpoint revealed by the crystal structure of the symmetric Mad2 dimer
AU - Yang, Maojun
AU - Li, Bing
AU - Liu, Chyong Jy
AU - Tomchick, Diana R
AU - Machius, Mischa
AU - Rizo-Rey, Jose
AU - Yu, Hongtao
AU - Luo, Xuelian
PY - 2008/3
Y1 - 2008/3
N2 - In response to misaligned sister chromatids during mitosis, the spindle checkpoint protein Mad2 inhibits the anaphase-promoting complex or cyclosome (APC/C) through binding to its mitotic activator Cdc20, thus delaying anaphase onset. Mad1, an upstream regulator of Mad2, forms a tight core complex with Mad2 and facilitates Mad2 binding to Cdc20. In the absence of its binding proteins, free Mad2 has two natively folded conformers, termed N1-Mad2/open-Mad2 (O-Mad2) and N2-Mad2/closed Mad2 (C-Mad2), with C-Mad2 being more active in APC/C Cdc20 inhibition. Here, we show that whereas O-Mad2 is monomeric, C-Mad2 forms either symmetric C-Mad2-C-Mad2 (C-C) or asymmetric O-Mad2-C-Mad2 (O-C) dimers. We also report the crystal structure of the symmetric C-C Mad2 dimer, revealing the basis for the ability of unliganded C-Mad2, but not O-Mad2 or liganded C-Mad2, to form symmetric dimers. A Mad2 mutant that predominantly forms the C-C dimer is functional in vitro and in living cells. Finally, the Mad1-Mad2 core complex facilitates the conversion of O-Mad2 to C-Mad2 in vitro. Collectively, our results establish the existence of a symmetric Mad2 dimer and provide insights into Mad1-assisted conformational activation of Mad2 in the spindle checkpoint.
AB - In response to misaligned sister chromatids during mitosis, the spindle checkpoint protein Mad2 inhibits the anaphase-promoting complex or cyclosome (APC/C) through binding to its mitotic activator Cdc20, thus delaying anaphase onset. Mad1, an upstream regulator of Mad2, forms a tight core complex with Mad2 and facilitates Mad2 binding to Cdc20. In the absence of its binding proteins, free Mad2 has two natively folded conformers, termed N1-Mad2/open-Mad2 (O-Mad2) and N2-Mad2/closed Mad2 (C-Mad2), with C-Mad2 being more active in APC/C Cdc20 inhibition. Here, we show that whereas O-Mad2 is monomeric, C-Mad2 forms either symmetric C-Mad2-C-Mad2 (C-C) or asymmetric O-Mad2-C-Mad2 (O-C) dimers. We also report the crystal structure of the symmetric C-C Mad2 dimer, revealing the basis for the ability of unliganded C-Mad2, but not O-Mad2 or liganded C-Mad2, to form symmetric dimers. A Mad2 mutant that predominantly forms the C-C dimer is functional in vitro and in living cells. Finally, the Mad1-Mad2 core complex facilitates the conversion of O-Mad2 to C-Mad2 in vitro. Collectively, our results establish the existence of a symmetric Mad2 dimer and provide insights into Mad1-assisted conformational activation of Mad2 in the spindle checkpoint.
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UR - http://www.scopus.com/inward/citedby.url?scp=41749098779&partnerID=8YFLogxK
U2 - 10.1371/journal.pbio.0060050
DO - 10.1371/journal.pbio.0060050
M3 - Article
C2 - 18318601
AN - SCOPUS:41749098779
VL - 6
SP - 643
EP - 655
JO - PLoS Biology
JF - PLoS Biology
SN - 1544-9173
IS - 3
M1 - e50
ER -