Different evolutionary strategies to conserve chromatin boundary function in the bithorax complex

Fabienne Cleard, Daniel Wolle, Andrew M. Taverner, Tsutomu Aoki, Girish Deshpande, Peter Andolfatto, Francois Karch, Paul Schedl

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Chromatin boundary elements subdivide chromosomes in multicellular organisms into physically independent domains. In addition to this architectural function these elements also play a critical role in gene regulation. Here we investigated the evolution of a Drosophila Bithorax complex boundary element called Fab-7 which is required for the proper parasegment specific expression of the homeotic Abd-B gene. Using a “gene” replacement strategy we show that Fab-7 boundaries from two closely related species D. erecta and D. yakuba and a more distant species D. pseudoobscura are able to substitute for the melanogaster boundary. Consistent with this functional conservation the two known Fab-7 boundary factors Elba and LBC have recognition sequences in the boundaries from all species. However the strategies used for maintaining binding and function in the face of sequence divergence is different. The first is conventional and depends upon conservation of the 8 bp Elba recognition sequence. The second is unconventional and takes advantage of the unusually large and flexible sequence recognition properties of the LBC boundary factor and the deployment of multiple LBC recognition elements in each boundary. In the former case binding is lost when the recognition sequence is altered. In the latter case sequence divergence is accompanied by changes in the number relative affinity and location of the LBC recognition elements.

Original languageEnglish (US)
Pages (from-to)589-603
Number of pages15
JournalGenetics
Volume205
Issue number2
DOIs
StatePublished - Feb 2017

All Science Journal Classification (ASJC) codes

  • Genetics

Keywords

  • Boundary element
  • Conservation of function
  • DNA binding proteins
  • Evolution
  • Insulator

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