Polycomb group protein Suppressor 2 of zeste is a functional homolog of Posterior Sex Combs.
The Drosophila melanogaster Polycomb group protein Posterior Sex Combs is a component of Polycomb repressive complex 1 and is central to Polycomb group-mediated silencing. A related Polycomb group gene, Suppressor 2 of zeste, is thought to be partially redundant in function. The two proteins share a small region of homology but also contain regions of unconserved sequences. Here we report a biochemical characterization of Suppressor 2 of zeste. Like Posterior Sex Combs, Suppressor 2 of zeste binds DNA, compacts chromatin, and inhibits chromatin remodeling. Interestingly, the regions of the two proteins responsible for these activities lack sequence homology. Suppressor 2 of zeste can also replace Posterior Sex Combs in a functional complex with other Polycomb group proteins, but unlike with their biochemical activities, complex formation is mediated by the region of Suppressor 2 of zeste that is homologous to that of Posterior Sex Combs. Our results establish Suppressor 2 of zeste as a functional homolog of Posterior Sex Combs and suggest that the two proteins operate via similar molecular mechanisms.
Lo
Stanley M
SM
Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138.
Ahuja
Nitin K
NK
Francis
Nicole J
NJ
D000818:Animals; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D009707:Nucleosomes / Q000378:metabolism; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009707:Nucleosomes; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; C071051:Su(z)2 protein, Drosophila; C071050:Psc protein, Drosophila; D004247:DNA; D063150:Polycomb Repressive Complex 1