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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Volume 332 | Issue 6026
8 April 2011
8 April 2011
Copyright © 2011, American Association for the Advancement of Science.
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Received: 22 October 2010
Accepted: 8 February 2011
Published in print: 8 April 2011
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We thank B.N. Ross and G.D. Martens of the UBC Bioimaging Facility and A.M. Chan for assistance with electron microscopy; E. Zaikova for qPCR assistance; and E. J. Pritham, J. Davies, and E. Nomis for constructive comments. Supported by the Natural Science and Engineering Research Council of Canada (NSERC) Discovery Grants Program, the Tula Foundation through the Centre for Microbial Diversity and Evolution, and fellowships awarded to M.G.F. by the Gottlieb Daimler- and Karl Benz-Foundation, Germany, and the University of British Columbia. The genome sequence of Mavirus has been deposited in GenBank under the accession number HQ712116.
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