Related Experiment Videos
A point mutation in the MyoD basic domain imparts c-Myc-like properties
M E Van Antwerp1, D G Chen, C Chang
1Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor 48109.
Summary
Researchers altered the MyoD protein
Area of Science:
- Molecular Biology
- Genetics
- Protein Function
Background:
- MyoD and c-Myc are basic-helix-loop-helix proteins regulating growth and gene expression.
- They differ in critical amino acids within their DNA-binding basic domains.
Purpose of the Study:
- To investigate the role of specific amino acids in the MyoD basic domain on DNA binding and transcriptional activation.
- To determine if mutations can alter MyoD's DNA-binding specificity.
Main Methods:
- Site-directed mutagenesis of the MyoD basic domain, substituting amino acids with those from c-Myc.
- Assessing DNA binding affinity to MyoD and c-Myc binding sites.
- Evaluating transcriptional activation of MyoD-responsive genes and suppression of c-Myc-responsive promoters.
Main Results:
- Mutations yielded four classes, affecting DNA binding and/or activation.
- A specific mutant (mut 9, Leu122Arg) retained MyoD-site binding but gained c-Myc-site binding.
- Mut 9 competed with wild-type MyoD and suppressed a c-Myc-regulated promoter.
Conclusions:
- Specific amino acid residues in the MyoD basic domain are crucial for DNA-binding specificity and transcriptional activity.
- Leucine 122 in MyoD is a key determinant of DNA-binding specificity, with mutation altering target recognition.