Related Experiment Videos
Interaction between two homeodomain proteins is specified by a short C-terminal tail
1Department of Biochemistry and Biophysics, School of Medicine, University of California, San Francisco 94143-0502.
Nature
|September 29, 1994
Summary
Yeast homeodomain proteins a1 and alpha 2 bind DNA cooperatively to control cell type determination genes. A specific tail region on alpha 2 is crucial for this interaction, enabling novel DNA binding specificity.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Protein-DNA Interactions
Background:
- Two yeast homeodomain proteins, a1 and alpha 2, regulate cell type determination by binding to the haploid-specific gene (hsg) operator.
- Their cooperative DNA binding is essential for gene repression.
Purpose of the Study:
- To investigate how two DNA-binding proteins with varying specificities (a1 and alpha 2) create a highly specific DNA-binding complex.
- To identify the functional domains of a1 and alpha 2 involved in cooperative DNA binding.
Main Methods:
- In vitro reconstitution of cooperative DNA binding using purified protein fragments.
- Construction and analysis of chimeric proteins between a1, alpha 2, and Drosophila engrailed homeodomain.
Main Results:
- The homeodomain of a1 and a 22-amino-acid C-terminal tail of alpha 2 are required for cooperative binding.
- The alpha 2 tail, when fused to the a1 homeodomain, confers strong DNA-binding ability.
- This alpha 2 tail can also mediate cooperative binding with a1 when fused to other homeodomains, like Drosophila engrailed.
Conclusions:
- The C-terminal tail of alpha 2 plays a critical role in facilitating specific DNA binding in the a1/alpha 2 heterodimer.
- Protein engineering by grafting functional domains can create novel DNA-binding specificities, demonstrating a versatile mechanism for generating new transcription factor activities.