Suppressor mutation of position-effect variegation in Drosophila melanogaster affecting chromatin properties

The dominant mutation Su-var(2)1⁰¹which suppresses position-effect variegation and displays recessive butyrate sensitivity was found to result in significant hyperacetylation of histone H4. This biochemical finding, as well as the genetic properties of this mutation, strongly suggest that the wild-type product of the corresponding locus is involved in histone H4 deacetylation. In larvae containing the suppressor mutation the accessibility of chromatin to endogenous nucleases is significantly increased which might be causally connected with histone H4 hyperacetylation. The suppressor mutation Su-var(2)1⁰¹has, therefore, to be classified as a chromatin condensation mutation.