Amino acid sequence homology between Piv, an essential protein in site-specific DNA inversion in Moraxella lacunata, and transposases of an unusual family of insertion elements.

Deletion analysis of the subcloned DNA inversion region of Moraxella lacunata indicates that Piv is the only M. lacunata-encoded factor required for site-specific inversion of the tfpQ/tfpI pilin segment. The predicted amino acid sequence of Piv shows significant homology solely with the transposases/integrases of a family of insertion sequence elements, suggesting that Piv is a novel site-specific recombinase.