Mobile DNA elements: controlling transposition with ATP-dependent molecular switches

Nucleotide-binding proteins are often used as molecular switches to control the assembly or activity of macromolecular machines. Recent work has revea led that such molecular switches also regulate the spread of some mobile DN A elements. Bacteriophage Mu and the bacterial transposon Tn7 each use an A TP-dependent molecular switch to select a new site for insertion and to coo rdinate the assembly of the transposition machinery at that site. Strong pa rallels between these ATP-dependent transposition proteins and other well-c haracterized molecular switches, such as Ras and EF-Tu, have emerged.