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

EMBO Rep. 2001 Dec;2(12):1095-100. doi: 10.1093/embo-reports/kve243. Epub 2001 Nov 21.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AT Rich Sequence / genetics
  • Animals
  • Base Sequence
  • Binding Sites
  • Blotting, Western
  • Consensus Sequence
  • DNA / genetics
  • DNA / metabolism*
  • DNA, Satellite / genetics
  • DNA, Satellite / metabolism
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Drosophila / genetics*
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Gene Expression Regulation*
  • Gene Order / genetics*
  • Genes, Insect / genetics
  • Sequence Deletion / genetics
  • Zinc Fingers


  • DNA, Satellite
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Su(var)3-7 protein, Drosophila
  • DNA