Position-effect variegation in Drosophila: the modifier Su(var)3-7 is a modular DNA-binding protein
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Updated: Oct 3, 2026

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila
Published on: August 20, 2019
1Department of Zoology and Animal Biology, University of Geneva, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
Abstract:
An increase in the dose of the Su(var)3-7 locus of Drosophila augments heterochromatin-promoted variegated silencing. The deduced protein sequence of Su(var)3-7 reveals seven widely spaced zinc fingers. We found that Su(var)3-7 has affinity for DNA in vitro and that the minimal protein sequence requirement for DNA binding is any module containing two zinc fingers and the interval between them. As Su(var)3-7 is a heterochromatin-associated protein, we tested its affinity for various satellite DNA sequences in vitro. The AATAT and 353-bp elements have the highest affinity. If affinity for satellite DNAs contributes to the presence of Su(var)3-7 in heterochromatin, a general affinity for DNA, or sequences yet to be determined, suggests a function in the genomic silencing of position-effect variegation: expansion of heterochromatin, whether continuous by spreading or discontinuous by pairing with sequence elements scattered through euchromatin, could use the affinity of Su(var)3-7 for DNA.
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