Report

A Virophage at the Origin of Large DNA Transposons

Science  03 Mar 2011:

DOI: 10.1126/science.1199412

Abstract

DNA transposons are mobile genetic elements that have shaped the genomes of eukaryotes for millions of years, yet their origins remain obscure. We discovered a virophage that, on the basis of genetic homology, likely represents an evolutionary link between double-stranded DNA viruses and Maverick/Polinton eukaryotic DNA transposons. The Mavirus virophage parasitizes the giant Cafeteria roenbergensis virus and encodes 20 predicted proteins, including a retroviral integrase and a protein-primed DNA polymerase B. On the basis of our data, we conclude that Maverick/Polinton transposons may have originated from ancient relatives of Mavirus, and thereby influenced the evolution of eukaryotic genomes, although we cannot rule out alternative evolutionary scenarios.

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