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MLL and CREB bind cooperatively to the nuclear coactivator CREB-binding protein
1Department of Pathology, Harvard Medical School, Dana-Farber Cancer Institute, Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA.
Molecular and Cellular Biology
|March 22, 2001
Summary
The mixed-lineage leukemia (MLL) gene interacts with CREB-binding protein (CBP), a key transcriptional coactivator. This interaction enhances MLL
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The mixed-lineage leukemia (MLL) gene plays a crucial role in gene regulation.
- CREB-binding protein (CBP) is a vital transcriptional coactivator involved in numerous cellular processes.
- Understanding protein-protein interactions is essential for deciphering complex gene regulatory networks.
Purpose of the Study:
- To identify proteins interacting with the CREB-CBP complex.
- To characterize the interaction between MLL and CBP.
- To elucidate the functional significance of the MLL-CBP interaction in transcriptional regulation.
Main Methods:
- Yeast genetic screening to identify interacting proteins.
- In vitro binding assays to map interaction domains.
- Site-directed mutagenesis to identify critical residues for interaction.
- Transactivation assays to assess functional consequences.
Main Results:
- A fragment of the MLL gene was identified as interacting with CBP, not CREB.
- The minimal interaction region was mapped to specific amino acid domains within MLL and CBP.
- MLL's transactivation activity was dependent on CBP, and specific MLL residues were critical for this interaction.
- The MLL activation domain facilitated CBP binding to phosphorylated CREB, revealing a cooperative mechanism.
Conclusions:
- MLL directly interacts with CBP through a defined activation domain.
- This interaction is crucial for MLL-mediated transcriptional activation.
- MLL and CREB can cooperatively target the same motif on CBP, challenging previous models of coactivator competition.