A Drosophila Polycomb group complex includes Zeste and dTAFII proteins.
A goal of modern biology is to identify the physical interactions that define 'functional modules' of proteins that govern biological processes. One essential regulatory process is the maintenance of master regulatory genes, such as homeotic genes, in an appropriate 'on' or 'off' state for the lifetime of an organism. The Polycomb group (PcG) of genes maintain a repressed transcriptional state, and PcG proteins form large multiprotein complexes, but these complexes have not been described owing to inherent difficulties in purification. We previously fractionated a major PcG complex, PRC1, to 20-50% homogeneity from Drosophila embryos. Here, we identify 30 proteins in these preparations, then further fractionate the preparation and use western analyses to validate unanticipated connections. We show that the known PcG proteins Polycomb, Posterior sex combs, Polyhomeotic and dRING1 exist in robust association with the sequence-specific DNA-binding factor Zeste and with numerous TBP (TATA-binding-protein)-associated factors that are components of general transcription factor TFIID (dTAFIIs). Thus, in fly embryos, there is a direct physical connection between proteins that bind to specific regulatory sequences, PcG proteins, and proteins of the general transcription machinery.
Saurin
A J
AJ
Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Shao
Z
Z
Erdjument-Bromage
H
H
Tempst
P
P
Kingston
R E
RE
D000818:Animals; D015153:Blotting, Western; D002850:Chromatography, Gel; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000502:physiology; D004330:Drosophila; D029721:Drosophila Proteins; D005786:Gene Expression Regulation; D017344:Genes, Insect; D019476:Insect Proteins / Q000737:chemistry* / Q000502:physiology; D013058:Mass Spectrometry; D063150:Polycomb Repressive Complex 1; D011233:Precipitin Tests; D011485:Protein Binding; D035362:Transcription Factor TFIID; D019473:Transcription Factors, TFII / Q000032:analysis* / Q000502:physiology; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; C066770:Pc protein, Drosophila; D035362:Transcription Factor TFIID; D019473:Transcription Factors, TFII; C060849:z protein, Drosophila; D004247:DNA; D063150:Polycomb Repressive Complex 1