A stage-specific factor confers Fab-7 boundary activity during early embryogenesis in Drosophila.
The Fab-7 boundary is required to ensure that the iab-6 and iab-7 cis-regulatory domains in the Drosophila Bithorax complex can function autonomously. Though Fab-7 functions as a boundary from early embryogenesis through to the adult stage, this constitutive boundary activity depends on subelements whose activity is developmentally restricted. In the studies reported here, we have identified a factor, called early boundary activity (Elba), that confers Fab-7 boundary activity during early embryogenesis. The Elba factor binds to a recognition sequence within a Fab-7 subelement that has enhancer-blocking activity during early embryogenesis, but not during mid-embryogenesis or in the adult. We found that the Elba factor is present in early embryos but largely disappears during mid-embryogenesis. We show that mutations in the Elba recognition sequence that eliminate Elba binding in nuclear extracts disrupt the early boundary activity of the Fab-7 subelement. Conversely, we find that early boundary activity can be reconstituted by multimerizing the Elba recognition site.
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Tsutomu
T
Aoki
Susan
S
Schweinsberg
Julia
J
Manasson
Paul
P
Schedl
D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster / Q000196:embryology*; D004625:Embryo, Nonmammalian; D047108:Embryonic Development; D004742:Enhancer Elements, Genetic; D009687:Nuclear Proteins / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*
D029721:Drosophila Proteins; C465760:ElB protein, Drosophila; D009687:Nuclear Proteins; D014157:Transcription Factors