THE CHROMODOMAIN PROTEIN SWI6 - A KEY COMPONENT AT FISSION YEAST CENTROMERES

Centromeres attach chromosomes to the spindle during mitosis, thereby ensuring the equal distribution of chromosomes into daughter cells. Tr anscriptionally silent heterochromatin of unknown function is associat ed with centromeres in many organisms. In the fission yeast Schizosacc haromyces pombe, the silent mating-type loci, centromeres, and telomer es are assembled into silent heterochromatin-like domains. The Swi6 ch romodomain protein affects this silencing, and now it is shown that Sw i6p localizes with these three chromosomal regions. In cells lacking S wi6p, centromeres lag on the spindle during anaphase and chromosomes a re lost at high rates. Thus, Swi6p is located at fission yeast centrom eres and is required for their proper function.