The four human muscle regulatory helix-loop-helix proteins Myf3-Myf6 exhibit similar hetero-dimerization and DNA binding properties
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1Department of Toxicology, Medical School, University of Hamburg, FRG.
Insights
Four muscle regulatory helix-loop-helix (HLH) proteins exhibit similar DNA binding and dimerization. Combinations with other HLH proteins do not alter DNA sequence recognition by Myf proteins, suggesting limited combinatorial control.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Muscle regulatory proteins Myf3-Myf6 possess a conserved helix-loop-helix (HLH) domain.
- This domain is crucial for DNA binding and protein dimerization.
Purpose of the Study:
- To investigate the DNA binding and dimerization properties of human Myf proteins.
- To determine if combinatorial associations of Myf proteins influence DNA sequence recognition.
Main Methods:
- In vitro analysis of protein complex formation and DNA binding affinities.
- Electrophoretic mobility shift assays (EMSAs) to assess binding to E-box DNA sequences.
Main Results:
- Human Myf proteins (Myf3-Myf6) display similar dimerization with ubiquitously expressed HLH proteins (E12, E2-2, E2-5).
- All Myf protein complexes bind the E-box DNA sequence (CANNTG) with comparable efficiency.
- Binding affinity is modulated by nucleotides flanking the E-box consensus motif.
- Combinations of Myf proteins with each other or with lyl-1 do not bind DNA.
Conclusions:
- Myf proteins share conserved DNA binding and dimerization capabilities.
- Combinatorial interactions among Myf proteins and other HLH factors do not lead to differential DNA sequence recognition.
Abstract:
The muscle regulatory proteins Myf3, Myf4, Myf5, and Myf6 share a highly conserved DNA binding and dimerization domain consisting of a cluster of basic amino acids and a potential helix-loop-helix structure. Here we demonstrate that the four human muscle-specific HLH proteins have similar DNA binding and dimerization properties. The members of this family form protein complexes of comparable stability with the ubiquitously expressed HLH proteins E12, E2-2, and E2-5 and bind to the conserved DNA sequence CANNTG designated as E-box with similar efficiency in vitro. The binding affinities of the various complexes are greatly influenced by the variable internal and flanking nucleotides of the consensus motif. Combinations of Myf proteins with one another and with lyl-1, and HLH protein from human T cells, do not bind to DNA in vitro. Our results suggest that combinatorial associations of the various tissue-specific and more widely expressed HLH factors do not result in differential recognition of DNA sequences by Myf proteins.