Abstract
Mobile DNA elements are found in all kingdoms of life, and they employ numerous mechanisms to move within and between genomes. Here we review recent structural advances in understanding two very different families of DNA transposases and retroviral integrases: the DDE and Y1 groups. Even within the DDE family which shares a conserved catalytic domain, there is great diversity in the architecture of the synaptic complexes formed by the intact enzymes with their cognate element-end DNAs. However, recurring themes arise from comparing these complexes, such as stabilization by an intertwined network of protein-DNA and protein-protein contacts, and catalysis in trans, where each active subunit catalyzes the chemical steps on one DNA segment but also binds specific sequences on the other.