Positive control mutations in the MyoD basic region fail to show cooperative DNA binding and transcriptional activation in vitro.
An in vitro transcription system from HeLa cells has been established in which MyoD and E47 proteins activate transcription both as homodimers and heterodimers. However, heterodimers activate transcription more efficiently than homodimers, and function synergistically from multiple binding sites. Positive control mutants in the basic region of MyoD that have previously been shown to be defective in initiating the myogenic program, can bind DNA but have lost their ability to function as transcriptional activators in vitro. Additionally, positive control mutants, unlike wild-type MyoD, fail to bind cooperatively to DNA. We propose that binding of MyoD complexes to high affinity MyoD binding sites induces conformational changes that facilitate cooperative binding to multiple sites and promote transcriptional activation.
Salk Institute, San Diego, CA 92186-5800.
E
E
Bengal
O
O
Flores
P N
PN
Rangarajan
A
A
Chen
H
H
Weintraub
I M
IM
Verma
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004273:DNA, Neoplasm / Q000378:metabolism*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016297:Mutagenesis, Site-Directed; D017570:MyoD Protein / Q000235:genetics* / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D017354:Point Mutation; D014157:Transcription Factors / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic
D004273:DNA, Neoplasm; D046911:Macromolecular Substances; D017570:MyoD Protein; D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors