Unusual combinatorial involvement of poly-A/T tracts in organizing genes and chromatin in Dictyostelium

Gue Su Chang, Angelika A. Noegel, Travis N. Mavrich, Rolf Müller, Lynn Tomsho, Elissa Ward, Marius Felder, Cizhong Jiang, Ludwig Eichinger, Gernot Glöckner, Stephan C. Schuster, B. Franklin Pugh

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Dictyostelium discoideum is an amoebozoa that exists in both a free-living unicellular and a multicellular form. It is situated in a deep branch in the evolutionary tree and is particularly noteworthy in having a very A/T-rich genome. Dictyostelium provides an ideal system to examine the extreme to which nucleotide bias may be employed in organizing promoters, genes, and nucleosomes across a genome. We find that Dictyostelium genes are demarcated precisely at their 5′ ends by poly-T tracts and precisely at their 3′ ends by poly-A tracts. These tracts are also associated with nucleosome-free regions and are embedded with precisely positioned TATA boxes. Homo- and heteropolymeric tracts of A and T demarcate nucleosome border regions. Together, these findings reveal the presence of a variety of functionally distinct polymeric A/T elements. Strikingly, Dictyostelium chromatin may be organized in di-nucleosome units but is otherwise organized as in animals. This includes a +1 nucleosome in a position that predicts the presence of a paused RNA polymerase II. Indeed, we find a strong phylogenetic relationship between the presence of the NELF pausing factor and positioning of the +1 nucleosome. Pausing and +1 nucleosome positioning may have coevolved in animals.

Original languageEnglish (US)
Pages (from-to)1098-1106
Number of pages9
JournalGenome research
Volume22
Issue number6
DOIs
StatePublished - Jun 2012

All Science Journal Classification (ASJC) codes

  • Genetics
  • Genetics(clinical)

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