title: Visible periodicity of strong nucleosome DNA sequences.
abstract: Fifteen years ago, Lowary and Widom assembled nucleosomes on synthetic random sequence DNA molecules, selected the strongest nucleosomes and discovered that the TA dinucleotides in these strong nucleosome sequences often appear at 10-11 bases from one another or at distances which are multiples of this period. We repeated this experiment computationally, on large ensembles of natural genomic sequences, by selecting the strongest nucleosomes--i.e. those with such distances between like-named dinucleotides, multiples of 10.4 bases, the structural and sequence period of nucleosome DNA. The analysis confirmed the periodicity of TA dinucleotides in the strong nucleosomes, and revealed as well other periodic sequence elements, notably classical AA and TT dinucleotides. The matrices of DNA bendability and their simple linear forms--nucleosome positioning motifs--are calculated from the strong nucleosome DNA sequences. The motifs are in full accord with nucleosome positioning sequences derived earlier, thus confirming that the new technique, indeed, detects strong nucleosomes. Species- and isochore-specific variations of the matrices and of the positioning motifs are demonstrated. The strong nucleosome DNA sequences manifest the highest hitherto nucleosome positioning sequence signals, showing the dinucleotide periodicities in directly observable rather than in hidden form.
authors.affiliation: a Genome Diversity Center, Institute of Evolution, University of Haifa , Mount Carmel, Haifa 31905 , Israel.
authors.forename: Bilal
authors.initials: B
authors.lastname: Salih
authors.forename: Vijay
authors.initials: V
authors.lastname: Tripathi
authors.forename: Edward N
authors.initials: EN
authors.lastname: Trifonov
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000235:genetics*; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D015226:Dinucleoside Phosphates / Q000235:genetics*; D049751:Genome, Helminth / Q000235:genetics; D015894:Genome, Human / Q000235:genetics; D018745:Genome, Plant / Q000235:genetics; D006801:Humans; D032085:Isochores / Q000235:genetics*; D008969:Molecular Sequence Data; D009707:Nucleosomes / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D018509:DNA, Helminth; D018744:DNA, Plant; D015226:Dinucleoside Phosphates; D032085:Isochores; D009707:Nucleosomes; D004247:DNA
keywords: bendability matrix; chromatin code; isochore; nucleosome positioning; nucleosome positioning motif; sequence periodicity