Abstract
Proper chromosome alignment and segregation during mitosis depend on cohesion between sister chromatids, mediated by the cohesin protein complex, which also plays crucial roles in diverse genome maintenance pathways. Current models attribute DNA binding by cohesin to entrapment of dsDNA by the cohesin ring subunits (SMC1, SMC3, and RAD21 in humans). However, the biophysical properties and activities of the fourth core cohesin subunit SA2 (STAG2) are largely unknown. Here, using single-molecule atomic force and fluorescence microscopy imaging as well as fluorescence anisotropy measurements, we established that SA2 binds to both dsDNA and ssDNA, albeit with a higher binding affinity for ssDNA. We observed that SA2 can switch between the 1D diffusing (search) mode on dsDNA and stable binding (recognition) mode at ssDNA gaps. Although SA2 does not specifically bind to centromeric or telomeric sequences, it does recognize DNA structures often associated with DNA replication and double-strand break repair, such as a double-stranded end, single-stranded overhang, flap, fork, and ssDNA gap. SA2 loss leads to a defect in homologous recombination–mediated DNA double-strand break repair. These results suggest that SA2 functions at intermediate DNA structures during DNA transactions in genome maintenance pathways. These findings have important implications for understanding the function of cohesin in these pathways.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1054-1069 |
| Number of pages | 16 |
| Journal | Journal of Biological Chemistry |
| Volume | 293 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jan 1 2018 |
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ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology
Cite this
Cohesin SA2 is a sequence-independent DNA-binding protein that recognizes DNA replication and repair intermediates. / Countryman, Preston; Fan, Yanlin; Gorthi, Aparna; Pan, Hai; Strickland, Jack; Kaur, Parminder; Wang, Xuechun; Lin, Jiangguo; Lei, Xiaoying; White, Christian; You, Changjiang; Wirth, Nicolas; Tessmer, Ingrid; Piehler, Jacob; Riehn, Robert; Bishop, Alexander J; Tao, Yizhi Jane; Wang, Hong.
In: Journal of Biological Chemistry, Vol. 293, No. 3, 01.01.2018, p. 1054-1069.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Cohesin SA2 is a sequence-independent DNA-binding protein that recognizes DNA replication and repair intermediates
AU - Countryman, Preston
AU - Fan, Yanlin
AU - Gorthi, Aparna
AU - Pan, Hai
AU - Strickland, Jack
AU - Kaur, Parminder
AU - Wang, Xuechun
AU - Lin, Jiangguo
AU - Lei, Xiaoying
AU - White, Christian
AU - You, Changjiang
AU - Wirth, Nicolas
AU - Tessmer, Ingrid
AU - Piehler, Jacob
AU - Riehn, Robert
AU - Bishop, Alexander J
AU - Tao, Yizhi Jane
AU - Wang, Hong
PY - 2018/1/1
Y1 - 2018/1/1
N2 - Proper chromosome alignment and segregation during mitosis depend on cohesion between sister chromatids, mediated by the cohesin protein complex, which also plays crucial roles in diverse genome maintenance pathways. Current models attribute DNA binding by cohesin to entrapment of dsDNA by the cohesin ring subunits (SMC1, SMC3, and RAD21 in humans). However, the biophysical properties and activities of the fourth core cohesin subunit SA2 (STAG2) are largely unknown. Here, using single-molecule atomic force and fluorescence microscopy imaging as well as fluorescence anisotropy measurements, we established that SA2 binds to both dsDNA and ssDNA, albeit with a higher binding affinity for ssDNA. We observed that SA2 can switch between the 1D diffusing (search) mode on dsDNA and stable binding (recognition) mode at ssDNA gaps. Although SA2 does not specifically bind to centromeric or telomeric sequences, it does recognize DNA structures often associated with DNA replication and double-strand break repair, such as a double-stranded end, single-stranded overhang, flap, fork, and ssDNA gap. SA2 loss leads to a defect in homologous recombination–mediated DNA double-strand break repair. These results suggest that SA2 functions at intermediate DNA structures during DNA transactions in genome maintenance pathways. These findings have important implications for understanding the function of cohesin in these pathways.
AB - Proper chromosome alignment and segregation during mitosis depend on cohesion between sister chromatids, mediated by the cohesin protein complex, which also plays crucial roles in diverse genome maintenance pathways. Current models attribute DNA binding by cohesin to entrapment of dsDNA by the cohesin ring subunits (SMC1, SMC3, and RAD21 in humans). However, the biophysical properties and activities of the fourth core cohesin subunit SA2 (STAG2) are largely unknown. Here, using single-molecule atomic force and fluorescence microscopy imaging as well as fluorescence anisotropy measurements, we established that SA2 binds to both dsDNA and ssDNA, albeit with a higher binding affinity for ssDNA. We observed that SA2 can switch between the 1D diffusing (search) mode on dsDNA and stable binding (recognition) mode at ssDNA gaps. Although SA2 does not specifically bind to centromeric or telomeric sequences, it does recognize DNA structures often associated with DNA replication and double-strand break repair, such as a double-stranded end, single-stranded overhang, flap, fork, and ssDNA gap. SA2 loss leads to a defect in homologous recombination–mediated DNA double-strand break repair. These results suggest that SA2 functions at intermediate DNA structures during DNA transactions in genome maintenance pathways. These findings have important implications for understanding the function of cohesin in these pathways.
UR - http://www.scopus.com/inward/record.url?scp=85041011568&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85041011568&partnerID=8YFLogxK
U2 - 10.1074/jbc.M117.806406
DO - 10.1074/jbc.M117.806406
M3 - Article
C2 - 29175904
AN - SCOPUS:85041011568
VL - 293
SP - 1054
EP - 1069
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 3
ER -