A single active site in the mariner transposase cleaves DNA strands of opposite polarity.

摘要: The RNase H structural fold defines a large family of nucleic acid metabolizing enzymes that catalyze phosphoryl transfer reactions using two divalent metal ions in the active site. Almost all these involve only one strand substrates. In contrast, cut-and-paste transposases cleave DNA strands opposite polarity, which is usually achieved via an elegant hairpin mechanism. mariner transposons, intermediate absent and key aspects mechanism by transposon ends are cleaved remained unknown. Here, we characterize complexes involved prior to catalysis, define asymmetric pathway for transpososome assembly. Using mixtures wild-type catalytically inactive transposases, show catalytic steps transposition occur within context dimeric transpososome. Crucially, find each site transposase dimer responsible hydrolysis transesterification reaction at same end. These results provide first strong evidence DDE/D can hydrolyze has rarely been observed with any type nuclease.