Schweinsberg, S., Hagstrom, K., Gohl, D., Schedl, P., Kumar, R.P., Mishra, R., Karch, F. (2004). The enhancer-blocking activity of the Fab-7 boundary from the Drosophila Bithorax complex requires GAGA-factor-binding sites.  Genetics 168(3): 1371--1384.

FBrf0180278

Research paper

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.

PMC1448804 (PMC) (EuropePMC)