Related Experiment Videos
Sequence-specific DNA binding of the B-cell-specific coactivator OCA-B
K L Cepek1, D I Chasman, P A Sharp
1Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA.
Genes & Development
|August 15, 1996
Summary
The coactivator OCA-B binds DNA directly, interacting with transcription factors Oct-1/Oct-2 to regulate immunoglobulin gene transcription in B-cells. This interaction involves specific DNA sequences and the POU domain, enabling differential gene regulation.
Area of Science:
- Molecular Biology
- Immunology
- Gene Regulation
Background:
- B-cell-specific immunoglobulin gene transcription relies on transcription factors like Oct-1/Oct-2 and coactivators.
- OCA-B (also known as Bob-1 or OBF-1) is a crucial B-cell-specific coactivator.
Purpose of the Study:
- To elucidate the molecular mechanism by which OCA-B interacts with transcription factors and DNA.
- To understand how OCA-B contributes to the specificity of B-cell gene regulation.
Main Methods:
- DNA-binding assays to assess OCA-B's interaction with octamer elements.
- Analysis of OCA-B's interaction with POU domain transcription factors (Oct-1/Oct-2).
- Investigating the role of specific DNA sequences and protein domains in binding.
Main Results:
- OCA-B directly binds DNA within the major groove of the octamer element, contingent on an adenine at the fifth position and interaction with the POU domain.
- An N-terminal fragment of OCA-B binds DNA with similar sequence specificity, even without the POU domain.
- OCA-B may undergo a POU-dependent conformational change, exposing its N-terminus for DNA recognition.
Conclusions:
- OCA-B's dual recognition of both the POU domain and specific DNA sequences provides a mechanism for differential gene regulation.
- This interaction is key to controlling octamer site-containing genes, particularly by the ubiquitous factor Oct-1 in B-cells.