TA-periodic ("601"-like) centromeric nucleosomes of A. thaliana.

The bulk of strong nucleosomes (SNs, with visibly periodic DNA sequences) is described by consensus pattern of 5 or 6 base runs of purines alternating with similar runs of pyrimidines - RR/YY SNs. Yet, the strongest known nucleosome positioning sequence, the 601 clone of Lowary and Widom, is rather periodic repetition of TA dinucleotides following one another every 10 bases. We located "601"-like TA-periodic sequences in the genome of A. thaliana. Several families of such sequences are discovered repeating almost exclusively in centromeres. Thus, while A. thaliana SNs of RR/YY type have strong affinity to pericentromeric regions, as it has been previously found, the SNs of TA periodic type concentrate rather in centromeres.