One mechanism for the generation of new genes in the retrotransposition of mRNA back into the genome, creating a new, intronless copy of the parental gene. The majority of these copies, lacking proper promoters, end up as “processed pseudgenes“. A neat paper recently published in PLoS Biology, however, demonstrates that a new gene generated by this mechanism in the primate lineage has actually rapidly evolved under positive selection. Strikingly, they’re able to precisely track the function of the protein over time by recreating ancestral variants. From the abstract:
A microtubular CDC14B variant spawned CDC14Bretro through retroposition in the hominoid ancestor 18â€“25 million years ago (Mya). CDC14Bretro evolved brain-/testis-specific expression after the duplication event and experienced a short period of intense positive selection in the African ape ancestor 7-12 Mya. Using resurrected ancestral protein variants, we demonstrate that by virtue of amino acid substitutions in distinct protein regions during this time, the subcellular localization of CDC14Bretro progressively shifted from the association with microtubules (stabilizing them) to an association with the endoplasmic reticulum. CDC14Bretro evolution represents a paradigm example of rapid, selectively driven subcellular relocalization, thus revealing a novel mode for the emergence of new gene function.
Pretty cool stuff.