In vivo analysis of scaffold-associated regions in Drosophila: a synthetic high-affinity SAR binding protein suppresses position effect variegation.

Scaffold-associated regions (SARs) were studied in Drosophila melanogaster by expressing a synthetic, high-affinity SAR-binding protein called MATH (multi-AT-hook), which consists of reiterated AT-hook peptide motifs; each motif is known to recognize a wide variety of short AT-rich sequences. MATH proteins were expressed specifically in the larval eye imaginal discs by means of the tetracycline-regulated transactivation system and tested for their effect on position effect variegation (PEV). MATH20, a highly potent SAR ligand consisting of 20 AT-hooks, was found to suppress whitemottled 4 variegation. This suppression required MATH20 expression at an early larval developmental stage. Our data suggest an involvement of the high AT-rich SARs in higher order chromatin structure and gene expression.