A NOVEL CIS-ACTING CENTROMERIC DNA ELEMENT AFFECTS S-POMBE CENTROMERIC CHROMATIN STRUCTURE AT A DISTANCE

The chromatin structure of the central core region of Schizosaccharomyces pc,mbe centromeric DNA is unusual. This distinctive chromatin structure is associated only with central core sequences in a functional context and is modulated by a novel cis-acting DNA element (centromere enhancer) within the functionally critical K centromeric repeat, which is found in multiple copies in all three S, pombe centromeres. The centromere enhancer alters central core chromatin structure from a distance and in an orientation-independent manner without altering the nucleosomal packaging of sequences between the enhancer and the central core. These findings suggest a functionally relevant structural interaction between the enhancer and the centromeric central core brought about by DNA looping.