The Drosophila snr1 and brm proteins are related to yeast SWI/SNF proteins and are components of a large protein complex.
During most of Drosophila development the regulation of homeotic gene transcription is controlled by two groups of regulatory genes, the trithorax group of activators and the Polycomb group of repressors. brahma (brm), a member of the trithorax group, encodes a protein related to the yeast SWI2/SNF2 protein, a subunit of a protein complex that assists sequence-specific activator proteins by alleviating the repressive effects of chromatin. To learn more about the molecular mechanisms underlying the regulation of homeotic gene transcription, we have investigated whether a similar complex exists in flies. We identified the Drosophila snr1 gene, a potential homologue of the yeast SNF5 gene that encodes a subunit of the yeast SWI/SNF complex. The snr1 gene is essential and genetically interacts with brm and trithorax (trx), suggesting cooperation in regulating homeotic gene transcription. The spatial and temporal patterns of expression of snr1 are similar to those of brm. The snr1 and brm proteins are present in a large (> 2 x 10(6) Da) complex, and they co-immunoprecipitate from Drosophila extracts. These findings provide direct evidence for conservation of the SWI/SNF complex in higher eucaryotes and suggest that the Drosophila brm/snr1 complex plays an important role in maintaining homeotic gene transcription during development by counteracting the repressive effects of chromatin.
Dingwall
A K
AK
Department of Developmental Biology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California 94305-5427, USA.
Beek
S J
SJ
McCallum
C M
CM
Tamkun
J W
JW
Kalpana
G V
GV
Goff
S P
SP
Scott
M P
MP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins; D012333:RNA, Messenger / Q000032:analysis; D000071796:SMARCB1 Protein; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D015003:Yeasts / Q000235:genetics
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human; C096659:Snr1 protein, Drosophila; D015534:Trans-Activators; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C086469:brm protein, Drosophila