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Simple and Fast Rolling Circle Amplification-Based Detection of Topoisomerase 1 Activity in Crude Biological Samples
Published on: December 2, 2022
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Biochemical analysis of TOPBP1 oligomerization
Ahhyun Kim1, Katrina Montales1, Kenna Ruis1
1Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, United States.
DNA Repair
|September 28, 2020
Summary
TOPBP1 oligomerization is driven by interactions between its BRCT domains, specifically requiring BRCT 2. This self-association allows TOPBP1 to bind RAD9 and RHINO simultaneously, facilitating DNA damage response activation, likely as a tetramer.
Area of Science:
- Molecular Biology
- Cellular Biology
- Biochemistry
Background:
- TOPBP1 acts as a scaffold protein in DNA damage response.
- TOPBP1's ability to form oligomers was known, but the mechanism and functional impact were unclear.
Purpose of the Study:
- To elucidate the mechanism of TOPBP1 self-association (oligomerization).
- To determine the functional consequences of TOPBP1 oligomerization for DNA damage response.
- To identify the specific oligomeric state required for ATR kinase activation.
Main Methods:
- Protein binding assays
- Biochemical techniques
- Analysis of BRCT domain interactions
Main Results:
- TOPBP1 oligomerization is mediated by interactions among a subset of its nine BRCT domains.
- An intact BRCT 2 domain is essential for TOPBP1 oligomerization, with BRCT1&2 interacting with itself and the BRCT4&5 pair.
- TOPBP1 oligomers can simultaneously bind RAD9 and RHINO without compromising oligomerization.
- A tetrameric state of TOPBP1 is likely required for ATR protein kinase activation.
Conclusions:
- TOPBP1 oligomerization is a regulated process involving specific BRCT domain interactions.
- TOPBP1's oligomeric structure enables simultaneous binding of RAD9 and RHINO, enhancing DNA damage signaling.
- The study identifies a tetrameric TOPBP1 complex as the likely functional unit for ATR kinase activation.
