On the organization of the nucleosomes associated with telomeric sequences

The functions of telomeres and, probably, of interstitial telomeric sequences (ITSs) are influenced by their chromatin structure and organization. Telomeres in higher eukaryotes fold into nucleosomes that are about 20-40 bp shorter than the nucleosomes associated with bulk chromatin. Although the functional relevance of this short nucleosomal organization remains unknown, it is believed that short nucleosomes should contribute to telomere function. Whereas telomeric nucleosomes have been widely studied in different organisms, very little is known about the nucleosomal organization of ITSs. Chinese hamster ITSs have been found to associate with short nucleosomes. However, we have found that Arabidopsis thaliana ITSs fold into nucleosomes that have a repeat length similar to bulk chromatin. We discuss how the primary sequence of telomeres and ITSs could influence their nucleosomal organization.