Bonus, a Drosophila TIF1 homolog, is a chromatin-associated protein that acts as a modifier of position-effect variegation

Genetics. 2005 Feb;169(2):783-94. doi: 10.1534/genetics.104.037085. Epub 2004 Nov 15.


Bonus, a Drosophila TIF1 homolog, is a nuclear receptor cofactor required for viability, molting, and numerous morphological events. Here we establish a role for Bonus in the modulation of chromatin structure. We show that weak loss-of-function alleles of bonus have a more deleterious effect on males than on females. This male-enhanced lethality is not due to a defect in dosage compensation or somatic sex differentiation, but to the presence of the Y chromosome. Additionally, we show that bonus acts as both an enhancer and a suppressor of position-effect variegation. By immunostaining, we demonstrate that Bonus is associated with both interphase and prophase chromosomes and through chromatin immunoprecipitation show that two of these sites correspond to the histone gene cluster and the Stellate locus.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Chromatin / genetics*
  • Chromatin / metabolism
  • Chromatin Immunoprecipitation
  • Drosophila / genetics*
  • Drosophila / metabolism
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Enhancer Elements, Genetic
  • Female
  • Gene Expression Regulation
  • Genes, Insect
  • Immunohistochemistry
  • Male
  • Microscopy, Confocal
  • Mutation
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Y Chromosome


  • Bon protein, Drosophila
  • Chromatin
  • Drosophila Proteins
  • Nuclear Proteins
  • Receptors, Cytoplasmic and Nuclear
  • Repressor Proteins
  • Transcription Factors
  • transcriptional intermediary factor 1