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Stepwise Evolution of Essential Centromere Function in a Drosophila Neogene

Science  07 Jun 2013:
Vol. 340, Issue 6137, pp. 1211-1214
DOI: 10.1126/science.1234393

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Essential Novelty

The evolution of essential function for newly originated genes presents a conundrum, in that prior to the gene's origin either the essential function was absent or else performed by another gene or set of genes. In order to better understand how new genes acquire essential function, Ross et al. (p. 1211) investigated the origin of the Drosophila gene Umbrea. Umbrea became an essential protein in certain Drosophila species through the gain of localization at the centromere and a role in chromosome segregation.

Abstract

Evolutionarily young genes that serve essential functions represent a paradox; they must perform a function that either was not required until after their birth or was redundant with another gene. How young genes rapidly acquire essential function is largely unknown. We traced the evolutionary steps by which the Drosophila gene Umbrea acquired an essential role in chromosome segregation in D. melanogaster since the gene's origin less than 15 million years ago. Umbrea neofunctionalization occurred via loss of an ancestral heterochromatin-localizing domain, followed by alterations that rewired its protein interaction network and led to species-specific centromere localization. Our evolutionary cell biology approach provides temporal and mechanistic detail about how young genes gain essential function. Such innovations may constantly alter the repertoire of centromeric proteins in eukaryotes.

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