Phosphate coordination and movement of DNA in the Tn5 synaptic complex: role of the (R)YREK motif.

Bacterial DNA transposition is an important model system for studying DNA recombination events such as HIV-1 DNA integration and RAG-1-mediated V(D)J recombination. This communication focuses on the role of protein-phosphate contacts in manipulating DNA structure as a requirement for transposition catalysis. In particular, the participation of the nontransferred strand (NTS) 5' phosphate in Tn5 transposition strand transfer is analyzed.

A bifunctional DNA binding region in Tn5 transposase.

Tn5 transposition is a complicated process that requires the formation of a highly ordered protein-DNA structure, a synaptic complex, to catalyse the movement of a sequence of DNA (transposon) into a target DNA. Much is known about the structure of the synaptic complex and the positioning of protein-DNA contacts, although many protein-DNA contacts remain largely unstudied. In particular, there is little evidence for the positioning of donor DNA and target DNA.

Tn5 synaptic complex formation: role of transposase residue W450.

A series of Tn5 transposases (Tnp's) with mutations at the conserved amino acid position W450, which was structurally predicted to be important for synapsis, have been generated and characterized. This study demonstrates that W450 is involved in hydrophobic (and possibly aromatic) contacts within the Tnp monomer that negatively regulate synaptic complex formation.