Open AccessMutations that disrupt DNA binding and dimer formation in the E47 helix-loop-helix protein map to distinct domains.
Author(s) -
Anna Voronova,
David Baltimore
Publication year - 1990
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.87.12.4722
Subject(s) - dna , mutant , mutagenesis , biology , basic helix loop helix , enhancer , dna binding protein , hmg box , dna binding domain , site directed mutagenesis , binding site , dna binding site , helix turn helix , gene , genetics , transcription factor , promoter , gene expression
A common DNA binding and dimerization domain containing an apparent "helix-loop-helix" (HLH) structure was recognized recently in a number of regulatory proteins, including the E47 and E12 proteins that bind to the kappa E2 motif in immunoglobulin kappa gene enhancer. The effect of site-directed mutagenesis on E47 protein multimerization and DNA binding was examined. Mutations in either putative helix domain disrupted protein dimerization and DNA binding. No DNA binding was observed when mutations were introduced in the basic region, but these mutants were able to dimerize. These basic region mutants were not able to bind to DNA as heterodimers with the wild-type E47 proteins, demonstrating that two functional basic regions are required for binding to DNA. Therefore the basic region mutants are "transdominant."