Boundary swapping in the Drosophila Bithorax complex.
Although the boundary elements of the Drosophila Bithorax complex (BX-C) have properties similar to chromatin insulators, genetic substitution experiments have demonstrated that these elements do more than simply insulate adjacent cis-regulatory domains. Many BX-C boundaries lie between enhancers and their target promoter, and must modulate their activity to allow distal enhancers to communicate with their target promoter. Given this complex function, it is surprising that the numerous BX-C boundaries share little sequence identity. To determine the extent of the similarity between these elements, we tested whether different BX-C boundary elements can functionally substitute for one another. Using gene conversion, we exchanged the Fab-7 and Fab-8 boundaries within the BX-C. Although the Fab-8 boundary can only partially substitute for the Fab-7 boundary, we find that the Fab-7 boundary can almost completely replace the Fab-8 boundary. Our results suggest that although boundary elements are not completely interchangeable, there is a commonality to the mechanism by which boundaries function. This commonality allows different DNA-binding proteins to create functional boundaries.
Iampietro
Carole
C
NCCR, Frontiers in Genetics, University of Geneva, Department of Zoology and Animal Biology, 30 Quai Ernest Ansermet, 1211 Geneva 11, Switzerland.
Cléard
Fabienne
F
Gyurkovics
Henrik
H
Maeda
Robert K
RK
Karch
François
F
D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004330:Drosophila / Q000235:genetics* / Q000254:growth & development*; D029721:Drosophila Proteins / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D005260:Female; D005785:Gene Conversion; D005801:Genes, Homeobox; D017344:Genes, Insect; D005816:Genetic Complementation Test; D018398:Homeodomain Proteins / Q000235:genetics*; D008297:Male; D005810:Multigene Family; D011401:Promoter Regions, Genetic
C062393:Abd-B proteins, Drosophila; D017931:DNA Primers; D029721:Drosophila Proteins; D018398:Homeodomain Proteins