Regulatory potential of nonautonomous mariner elements and subfamily crosstalk

Two naturally occurring nonautonomous mariner elements were tested in vivo for their ability to down-regulate excision of a target element in the pres ence of functional mariner transposase. The tested elements were the peach element isolated from Drosophila mauritiana, which encodes a transposase th at differs from the autonomous element Mos1 in four amino acid replacements , and the DTBZ1 element isolated from D. teissieri, which encodes a truncat ed protein consisting of the first 132 residues at the amino end of the nor mally 345-residue transposase. We provide evidence that the protein from th e peach element does interact to down-regulate wildtype transposase, indica ting that at least some nonautonomous elements in natural populations that retain their open reading frame may play a regulatory role. In contrast, ou r tests reveal at most a weak interaction between transposase from the auto nomous Mos1 element and the truncated protein from DTBZ1, and none between Mos1 transposase and that from the distantly related mariner-like element H imar1 identified in the horn fly Haematobia irritans. Hence, the extent of regulatory crosstalk between mariner-like elements may be limited to closel y related ones. The evolutionary implications of these results are discusse d.