Conserved sequence and functional domains in satellite 2 from three families of salamanders

Abstract

Thirteen satellite 2 elements from Ambystoma talpoideum and 16 from Amphiuma tridactylum were cloned, sequenced, and compared with the satellite 2 consensus from Notophthalmus viridescens. These elements have maintained a high degree of similarity during the 65-200 Myr that the salamander families, represented by the three species, have been separated. The DNA sequences of the consensus elements from A. talpoideum and A. tridactylum are 81% similar, and both are ∼65% similar to the N. viridescens consensus. In addition to its DNA sequence, the functional properties of satellite 2 have also been conserved. By selecting and analyzing clones that closely mimicked the consensus of each species, we were able to demonstrate that satellite 2 from each species was capable of promoting transcription after injection into Xenopus laevis oocytes and that synthetic transcripts of satellite 2 from each species were capable of catalyzing their own site-specific cleavage. These properties may be related to the process of retroposition, which was previously proposed to be responsible for the genomic proliferation of satellite 2. Each of these functional properties also has general biological interest.