Eukaryotic genomes function in the context of chromatin, but the roles of most nonhistone chromosomal proteins are far from understood. The D1 protein of Drosophila is an example of a chromosomal protein that has been fairly well characterized biochemically, but has nevertheless eluded functional description. To this end, we have undertaken a gain-of-function genetical analysis of D1, utilizing the GAL4-UAS system.
View Article and Find Full Text PDFThe D1 protein is a high mobility group A (HMGA)-like nonhistone chromosomal protein with primary localization to certain AT-rich satellite DNA sequences within heterochromatin. The binding of D1 to euchromatic sequences is less studied and the functional significance of its chromosomal associations is unclear. By taking advantage of existing P-insertion alleles of the D1 gene, I generated D1 null mutations to investigate the phenotypic effect of loss of the D1 gene.
View Article and Find Full Text PDFThe importance of a gene's natural chromatin environment for its normal expression is poignantly illustrated when a change in chromosome position results in variable gene repression, such as is observed in position effect variegation (PEV) when the Drosophila melanogaster white (omega) gene is juxtaposed with heterochromatin. The Enhancer of variegation 3-9 [E(var)3-9] gene was one of over a hundred loci identified in screens for mutations that dominantly modify PEV. Haploinsufficiency for E(var)3-9 enhances omegam4 variegation, as would be expected from increased heterochromatin formation.
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