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Specific DNA recognition by F Factor TraY involves beta-sheet residues
1Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
The Journal of Biological Chemistry
|July 3, 1999
Summary
The F Factor TraY protein plays a dual role in bacterial conjugation, regulating gene transcription and facilitating DNA transfer. Mutational analysis confirms its beta-sheet residues are crucial for DNA binding at the origin of transfer.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- The F Factor TraY protein is essential for efficient conjugal transfer in bacteria.
- TraY performs two key functions: regulating tra gene transcription and facilitating DNA nicking at the origin of transfer (oriT).
Purpose of the Study:
- To investigate the role of specific TraY protein residues in DNA binding and function.
- To determine if TraY belongs to the ribbon-helix-helix family of transcription factors based on its DNA interaction mechanism.
Main Methods:
- Engineering and characterization of six single-alanine substitution mutants of the F Factor TraY protein.
- Assessing mutant TraY protein stability, nonspecific DNA recognition, and specific binding affinity to the TraY oriT site.
Main Results:
- Most TraY mutants exhibited significantly reduced binding affinity to the oriT site.
- Mutant proteins largely retained near wild-type stability and nonspecific DNA recognition capabilities.
- These findings implicate specific beta-sheet residues in TraY's direct interaction with the oriT DNA sequence.
Conclusions:
- The beta-sheet residues of the F Factor TraY protein are critical for its specific DNA recognition at the oriT.
- These results support the classification of TraY within the ribbon-helix-helix family of transcription factors.