Characterisation of two topoisomerase 1 genes in the pufferfish (Fugu rubripes)

Eukaryotic DNA topoisomerase I manipulates the higher order structures of D NA. Only one functional topoisomerase 1 (top 1) gene has previously been id entified in any individual eukaryotic species. Here we report the identific ation and characterisation of two top 1 genes in the pufferfish. Fugu rubri pes This shows that the copy number of topi. like that of other topoisomera ses. may vary between eukaryotes. Both Fugu genes have 21 exons, a gene str ucture similar to that of human TOP1. Despite this conservation of structur e, and some non-coding elements, both genes are less than a tenth of the si ze of the human gene. Sequence and phylogenetic analyses have shown that th is duplication is ancient and also affects other species in the fish lineag e. (C) 2001 Elsevier Science B.V. All rights: reserved.