Heterochromatic genes in Drosophila: a comparative analysis of two genes

Genetics. 2006 Jul;173(3):1433-45. doi: 10.1534/genetics.106.056069. Epub 2006 Apr 30.

Abstract

Centromeric heterochromatin comprises approximately 30% of the Drosophila melanogaster genome, forming a transcriptionally repressive environment that silences euchromatic genes juxtaposed nearby. Surprisingly, there are genes naturally resident in heterochromatin, which appear to require this environment for optimal activity. Here we report an evolutionary analysis of two genes, Dbp80 and RpL15, which are adjacent in proximal 3L heterochromatin of D. melanogaster. DmDbp80 is typical of previously described heterochromatic genes: large, with repetitive sequences in its many introns. In contrast, DmRpL15 is uncharacteristically small. The orthologs of these genes were examined in D. pseudoobscura and D. virilis. In situ hybridization and whole-genome assembly analysis show that these genes are adjacent, but not centromeric in the genome of D. pseudoobscura, while they are located on different chromosomal elements in D. virilis. Dbp80 gene organization differs dramatically among these species, while RpL15 structure is conserved. A bioinformatic analysis in five additional Drosophila species demonstrates active repositioning of these genes both within and between chromosomal elements. This study shows that Dbp80 and RpL15 can function in contrasting chromatin contexts on an evolutionary timescale. The complex history of these genes also provides unique insight into the dynamic nature of genome evolution.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Chromosome Mapping
  • Cloning, Molecular
  • Conserved Sequence
  • Drosophila / genetics*
  • Drosophila / metabolism
  • Drosophila / ultrastructure
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / genetics
  • Evolution, Molecular
  • Heterochromatin*
  • Molecular Sequence Data
  • Ribosomal Proteins / genetics*
  • Ribosomal Proteins / metabolism
  • Sequence Alignment
  • Species Specificity
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism

Substances

  • Dbp80 protein, Drosophila
  • Drosophila Proteins
  • Heterochromatin
  • Ribosomal Proteins
  • RpL15 protein, Drosophila
  • Transcription Factors

Associated data

  • GENBANK/DQ426900
  • GENBANK/DQ426901
  • GENBANK/DQ426902
  • GENBANK/DQ426903