Drosophila homologs of the proto-oncogene product PEBP2/CBF beta regulate the DNA-binding properties of Runt.
The Drosophila runt gene is the founding member of the Runt domain family of transcriptional regulators. Mammalian Runt domain genes encode the alpha subunit of the heterometric DNA-binding factor PEBP2/CBF. The unrelated PEBP2/CBF beta protein interacts with the Runt domain to increase its affinity for DNA. The conserved ability of the Drosophila Runt protein to respond to the stimulating effect of mammalian PEBP2/CBF beta indicated that flies were likely to have a homologous beta protein. Using the yeast two-hybrid system to isolate cDNAs for Runt-interacting proteins, we identified two Drosophila genes, referred to as Brother and Big-brother, that have substantial sequence homology with PEBP2/CBF beta. Yeast two-hybrid experiments as well as in vitro DNA-binding studies confirmed the functional homology of the Brother, Big-brother, and PEBP2/CBF beta proteins and demonstrated that the conserved regions of the Runt and Brother proteins are required for their heterodimeric interaction. The DNA-bending properties of Runt domain proteins in the presence and absence of their partners were also examined. Our results show that Runt domain proteins bend DNA and that this bending is influenced by Brother protein family members, supporting the idea that heterodimerization is associated with a conformational change in the Runt domain. Analysis of expression patterns in Drosophila embryos revealed that Brother and Big-brother are likely to interact with runt in vivo and further suggested that the activity of these proteins is not restricted to their interaction with Runt.
Golling
G
G
Department of Biochemistry and Cell Biology, State University of New York at Stony Brook, 11794-5215, USA.
Li
L
L
Pepling
M
M
Stebbins
M
M
Gergen
J P
JP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D016415:Sequence Alignment; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009687:Nuclear Proteins; C493674:TfAP-2 protein, Drosophila; D050656:Transcription Factor AP-2; D014157:Transcription Factors; C080833:run protein, Drosophila