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Publication Abstract from PubMed

Helitrons are widespread eukaryotic DNA transposons that have significantly contributed to genome variability and evolution, in part because of their distinctive, replicative rolling-circle mechanism, which often mobilizes adjacent genes. Although most eukaryotic transposases form oligomers and use RNase H-like domains to break and rejoin double-stranded DNA (dsDNA), Helitron transposases contain a single-stranded DNA (ssDNA)-specific HUH endonuclease domain. Here, we report the cryo-electron microscopy structure of a Helitron transposase bound to the 5'-transposon end, providing insight into its multidomain architecture and function. The monomeric transposase forms a tightly packed assembly that buries the covalently attached cleaved end, protecting it until the second end becomes available. The structure reveals unexpected architectural similarity to TraI, a bacterial relaxase that also catalyzes ssDNA movement. The HUH active site suggests how two juxtaposed tyrosines, a feature of many replication initiators that use HUH nucleases, couple the conformational shift of an alpha-helix to control strand cleavage and ligation reactions.

The large bat Helitron DNA transposase forms a compact monomeric assembly that buries and protects its covalently bound 5'-transposon end.,Kosek D, Grabundzija I, Lei H, Bilic I, Wang H, Jin Y, Peaslee GF, Hickman AB, Dyda F Mol Cell. 2021 Oct 21;81(20):4271-4286.e4. doi: 10.1016/j.molcel.2021.07.028. , Epub 2021 Aug 16. PMID:34403695^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.