Repbase Reports

2007, Volume 7, Issue 2
February 28, 2007
Copyright © 2001-2016 - Genetic Information Research Institute
ISSN# 1534-830X
Page 111


A family of autonomous Kolobok transposons - a consensus.

Key Words:
Kolobok; DNA transposon; Interspersed Repeat; nonautonomous; non-autonomous; Passage-1_XT; Kolobok-1_XT
Xenopus tropicalis
Xenopus tropicalis
Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Amphibia; Batrachia; Anura; Mesobatrachia; Pipoidea; Pipidae; Xenopodinae; Xenopus; Silurana
[1] Authors:
Kapitonov,V.V. and Jurka,J.
Kolobok, a novel superfamily of eukaryotic DNA transposons.
Repbase Reports 7(2), 111-111 (2007)
DNA transposons from the Kolobok superfamily are characterized by the TTAA target site duplications, which are identical to these produced by the piggyBac transposons. However, while piggyBac transposons have 5'-YY termini, Kolobok transposons have 5'-RR termini. Autonomous Kolobok transposons encode the Kolobok transposase, which is not similar to any other proteins in eukaryotes and prokaryotes. Kolobok transposons are widely spread in different eukaryotic species, including protists, fungi, invertebrates, and vertebrates. Kolobok-1_XT is a consensus sequence of a family of autonomous Kolobok transposons that were active in the frog genome in a last few million years. The Kolobok-1_XT consensus sequence encodes two proteins: (i) the intronless 814-aa transposase, Kolobok-1_XT1p, composed of the THAP DNA-binding domain and catalytic "DDE" domain, which is conserved in all Kolobok transposases, and (ii) the 189-aa Kolobok-1_XT2p protein. The second protein is conserved in highly diverse Kolobok transposons present in the genomes of vertebrates (frog, fish), chordates (lancelet, sea urchin, sea squirt), and cnidarians (starlet sea anemone). Although the exact function of the second protein is not known, it is certain, based on the protein conservation, that it is necessary for Kolobok transpositions. Most likely, after its fusion with the ATP P2X receptor in the genome of a common ancestor of vertebrates some 500 million years ago, the second Kolobok protein was recruited into the host cellular machinery as a C-terminal portion of the vertebrate ATP P2X7 receptor. Together with numerous families of non-autonomous elements, Kolobok transposons constitute ~6% of the frog genome.
[1] (Consensus)
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