Properties of CENP-B and Its Target Sequence in a Satellite DNA

Abstract

The centromere plays an essential role in the proper segregation of eukaryotic chromosomes at mitosis and meiosis. The centromere is the multifunctional domain of chromosome responsible for sister chromatid association at the inner site and for microtubule attachment at the outer surface. It also acts as a mechanochemical motor for chromosome movement. These multiple centromere functions must, in some way, be directed by a cis-acting DNA sequence located in the centromere region. Indeed, specific centromere DNA sequences (CEN-DNA) were identified in two yeast species. In Saccharomyces cerevisiae, CEN-DNA consists of roughly 125 bp sequence composed of three conserved elements. In contrast, the centromere sequence of S. pombe is quite different from S. cerevisiae in length and sequence organization (Chikasige et al, 1989; Hahnenberger et al, 1989; Clarke, 1990). The molecular bases for understanding the structure and function of the centromere/ kinetochore domain have not been elucidated in higher eukaryotes. In mammalian cells, satellite DNAs are localized in the centromeric hetero-chromatin or heterochromatic arm. In all human chromosomes, the alpha satellite or alphoid DNA family, a highly repetitive DNA composed of about 170 bp fundamental monomer repeating units, is found at the primary constriction (Willard, 1990), Its function, however, has not been established.