The enhancer-blocking activity of the Fab-7 boundary from the Drosophila bithorax complex requires GAGA-factor-binding sites.

  • publication
  • 08-12-2004

Schweinsberg S, Hagstrom K, Gohl D, Schedl P, Kumar RP, Mishra R, Karch F. Genetics 2004 Nov;168(3):1371-84. 168/3/1371. 10.1534/genetics.104.029561. PMC1448804.

In the work reported here we have analyzed the role of the GAGA factor [encoded by the Trithorax-like (Trl) gene] in the enhancer-blocking activity of Frontabdominal-7 (Fab-7), a domain boundary element from the Drosophila melanogaster bithorax complex (BX-C). One of the three nuclease hypersensitive sites in the Fab-7 boundary, HS1, contains multiple consensus-binding sequences for the GAGA factor, a protein known to be involved in the formation and/or maintenance of nucleosome-free regions of chromatin. GAGA protein has been shown to localize to the Fab-7 boundary in vivo, and we show that it recognizes sequences from HS1 in vitro. Using two different transgene assays we demonstrate that GAGA-factor-binding sites are necessary but not sufficient for full Fab-7 enhancer-blocking activity. We show that distinct GAGA sites are required for different enhancer-blocking activities at different stages of development. We also show that the enhancer-blocking activity of the endogenous Fab-7 boundary is sensitive to mutations in the gene encoding the GAGA factor Trithorax-like.

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