Positive selection drives the evolution of rhino, a member of the heterochromatin protein 1 family in Drosophila.

摘要: Heterochromatin comprises a significant component of many eukaryotic genomes. In comparison to euchromatin, heterochromatin is gene poor, transposon rich, and late replicating. It serves important biological roles, from silencing accurate chromosome segregation, yet little known about the evolutionary constraints that shape heterochromatin. A complementary approach traditional one directly studying heterochromatic DNA sequence study evolution proteins bind define One best markers for protein 1 (HP1), which an essential, nonhistone chromosomal protein. Here we investigate molecular five HP1 paralogs present in Drosophila melanogaster. Three these have ubiquitous expression patterns adult tissues, whereas HP1D/rhino HP1E are expressed predominantly ovaries testes respectively. The also distinct localization preferences cells. Thus, Rhino localizes compartment tissue culture cells, but pattern HP1A lysine-9 dimethylated H3. Using population genetic analyses, find rhino has been subject positive selection all three domains protein: N-terminal chromo domain, C-terminal chromo-shadow hinge region connects two modules. Maximum likelihood analysis sequences 20 species reveals small number residues shadow repeated selection. rapid highly unusual encoding suggests involved conflict affects germline, belying notion simply passive recipient “junk DNA”