Birth, death and replacement of karyopherins in Drosophila.

Publication Type:

Journal Article

Source:

Molecular biology and evolution, Volume 29, Issue 5, p.1429-1440 (2012)

Keywords:

2012, Basic Sciences Division, Center-Authored Paper, Genomics Core Facility, Jan 12, January 2012, Shared Resources

Abstract:

Nucleo-cytoplasmic transport is a broadly conserved process across eukaryotes. Despite its essential function and conserved mechanism, components of the nuclear transport apparatus have been implicated in genetic conflicts in Drosophila, especially in the male germline. The best understood case is represented by a truncated Ran-GAP gene duplication that is part of the Segregation Distorter (SD) system in D. melanogaster. Consistent with the hypothesis that the nuclear transport pathway is at the heart of mediating genetic conflicts, both nucleoporins and directionality-imposing components of nuclear transport have previously been shown to evolve under positive selection. Here, we present a comprehensive phylogenomic analysis of importins (karyopherins) in Drosophila evolution. Importins are adaptor molecules that physically mediate the transport of cargo molecules and comprise the third component of the nuclear transport apparatus. We find that importins have been repeatedly gained and lost throughout various stages of Drosophila evolution, including two intriguing examples of an apparently coincident loss and gain of non-orthologous and non-canonical importin-α. While there are a few signatures of episodic positive selection, genetic innovation in importin evolution is more evident in patterns of recurrent gene birth and loss specifically for function in Drosophila testes, which is consistent with their role in supporting host genomes defense against segregation distortion.