Conserved sections of the transcription regulatory modules in Drosophila early genes, including homotypic transcription factor-binding sites, are arranged with an 84-nt period, which corresponds to the superhelical turn length of nucleosomal DNA

Abstract

The periodicity of nucleotide arrangement was studied for conserved regions of the regulatory modules of 16 early development genes in two Drosophila species. The relative disposition of the conserved segments was found to be a multiple of the length of one coil of the nucleosomal DNA superhelix. Homotypic and heterotypic clusters of transcription-factor binding sites were observed in the conserved regions. The sites are usually at a distance that corresponds to the coil length of superhelical DNA of the nucleosome. The transcription-factor binding sites were assumed to play a role in regulating DNA condensation according to the nucleosome type.