Self-association of chromo domain peptides

The chromo domain is a sequence motif first recognised in the Drosophila polycomb protein and heterochromatin protein (HP1), two proteins associated with stable and heritable transcriptional silencing. Polycomb is one of a number of genes that are required to prevent ectopic homeotic gene expression in Drosophila, while HP1, the product of the Drosophila melanogaster Su(var)205 gene, is associated with the phenomenon of position effect variegation. These proteins are believed to be components of chromatin-associated multi-protein complexes that bring about stable transcriptional silencing and the chromo domain has been implicated in chromatin targeting, probably through protein-protein interaction. Recently, mammalian homologues of both polycomb and HP1 have been described. Here we demonstrate for the first time that oligopeptides containing a chromo domain derived from the mouse polycomb homologue M33 form multimeric complexes in solution, supporting the role of the chromo domain in multiprotein complex assembly.