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The helix-loop-helix/leucine repeat transcription factor USF can be functionally regulated in a redox-dependent
P Pognonec1, H Kato, R G Roeder
1Rockefeller University, New York, New York 10021-6399.
The Journal of Biological Chemistry
|December 5, 1992
Summary
The transcription factor USF43
Area of Science:
- Molecular biology
- Biochemistry
- Cell biology
Background:
- The helix-loop-helix/leucine repeat transcription factor USF43 plays a role in gene regulation.
- Previous studies indicated that USF43 DNA-binding capacity is reduced under nonreducing conditions.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying the redox-dependent regulation of USF43 DNA binding.
- To investigate the role of cysteine residues in USF43 function.
Main Methods:
- Site-directed mutagenesis to identify critical cysteine residues.
- Biochemical assays to assess DNA-binding capacity and transcriptional activity.
- Redox-based crosslinking experiments to detect covalent modifications.
Main Results:
- The two cysteine residues in the USF43 helix-loop-helix domain are essential for redox regulation.
- Oxidation of these cysteine residues leads to intra- and intermolecular covalent crosslinking.
- Redox modulation of USF43 directly impacts its transcriptional activation potential in vitro.
Conclusions:
- USF43 DNA-binding and transcriptional activity are regulated by redox-dependent covalent modifications of its cysteine residues.
- These findings provide a molecular explanation for the regulation of USF43 function in response to cellular redox changes.
- The study addresses the paradox of USF43's strong activation potential and ubiquitous presence.
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