The Drosophila trithorax group proteins BRM, ASH1 and ASH2 are subunits of distinct protein complexes.
The trithorax group gene brahma (brm) encodes an activator of Drosophila homeotic genes that functions as the ATPase subunit of a large protein complex. To determine if BRM physically interacts with other trithorax group proteins, we purified the BRM complex from Drosophila embryos and analyzed its subunit composition. The BRM complex contains at least seven major polypeptides. Surprisingly, the majority of the subunits of the BRM complex are not encoded by trithorax group genes. Furthermore, a screen for enhancers of a dominant-negative brm mutation identified only one trithorax group gene, moira (mor), that appears to be essential for brm function in vivo. Four of the subunits of the BRM complex are related to subunits of the yeast chromatin remodeling complexes SWI/SNF and RSC. The BRM complex is even more highly related to the human BRG1 and hBRM complexes, but lacks the subunit heterogeneity characteristic of these complexes. We present biochemical evidence for the existence of two additional complexes containing trithorax group proteins: a 2 MDa ASH1 complex and a 500 kDa ASH2 complex. These findings suggest that BRM plays a role in chromatin remodeling that is distinct from the function of most other trithorax group proteins.
Papoulas
O
O
Department of Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA. tamkun@biology.ucsc.edu.
Beek
S J
SJ
Moseley
S L
SL
McCallum
C M
CM
Sarte
M
M
Shearn
A
A
Tamkun
J W
JW
D000595:Amino Acid Sequence; D000818:Animals; D015139:Blotting, Southern; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D003433:Crosses, Genetic; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D004330:Drosophila / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D020224:Expressed Sequence Tags; D006609:High Mobility Group Proteins; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D011233:Precipitin Tests; D029701:Saccharomyces cerevisiae Proteins; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D015003:Yeasts / Q000235:genetics
C490910:ASH1 protein, Drosophila; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006609:High Mobility Group Proteins; D019476:Insect Proteins; D009687:Nuclear Proteins; C103337:RSC complex, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C103604:ash2 protein, Drosophila; C086469:brm protein, Drosophila; C490911:ASH1L protein, human; D011495:Histone-Lysine N-Methyltransferase; C084108:SMARCA4 protein, human; D004265:DNA Helicases