Linked Life Data

9488706

Source:http://linkedlifedata.com/resource/pubmed/id/9488706

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1998-4-7
pubmed:abstractText
Basic region helix-loop-helix (bHLH) transcription factors regulate key steps in early development by binding to regulatory DNA sites as heterodimers consisting of a tissue-specific factor and a widely expressed factor. We have examined the folding, dimerization, and DNA binding properties of the muscle-specific bHLH protein MyoD and its partner E47, to understand why these proteins preferentially associate in heterodimeric complexes with DNA. In the absence of DNA, the E47 bHLH domain forms a very stable homodimer, whereas MyoD is unfolded and monomeric. Fluorescence quenching experiments show that MyoD does not dimerize with E47 under dilute conditions in the absence of DNA. Residues in and around the loop of the E47 bHLH domain contribute to its markedly greater stability. An altered MyoD bHLH substituted with the loop segment from E47 folds in the absence of DNA, and it readily dimerizes with E47. In the presence of a specific DNA binding site, MyoD and E47 both form homodimeric complexes with DNA that have similar dissociation constants, despite the very different stabilities of these protein dimers off DNA. A 1:1 mixture of these bHLH domains forms almost exclusively heterodimeric complexes on DNA. Assembly of these bHLH-DNA complexes is apparently governed by the strength of each subunit's interaction with the DNA and not by the strength of protein-protein interactions at the dimer interface. These findings suggest that preferential association of MyoD with E47 in DNA complexes results from more favorable DNA contacts made by one or both subunits of the heterodimer in comparison with either homodimeric complex.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
6
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5735-43
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed-meshheading:9488706-Amino Acid Sequence, pubmed-meshheading:9488706-Animals, pubmed-meshheading:9488706-Creatine Kinase, pubmed-meshheading:9488706-DNA-Binding Proteins, pubmed-meshheading:9488706-Dimerization, pubmed-meshheading:9488706-Fluorescence, pubmed-meshheading:9488706-Helix-Loop-Helix Motifs, pubmed-meshheading:9488706-Models, Molecular, pubmed-meshheading:9488706-Molecular Sequence Data, pubmed-meshheading:9488706-MyoD Protein, pubmed-meshheading:9488706-Protein Binding, pubmed-meshheading:9488706-Protein Folding, pubmed-meshheading:9488706-Protein Structure, Secondary, pubmed-meshheading:9488706-Recombinant Fusion Proteins, pubmed-meshheading:9488706-Recombinant Proteins, pubmed-meshheading:9488706-TCF Transcription Factors, pubmed-meshheading:9488706-Transcription Factor 7-Like 1 Protein, pubmed-meshheading:9488706-Transcription Factors
pubmed:year
1998
pubmed:articleTitle
DNA-mediated folding and assembly of MyoD-E47 heterodimers.
pubmed:affiliation
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't