INVERSION ACTIVITY OF THE TN5053 AND TN40 2 RESOLUTION SYSTEM, WHICH POSSESS AN UNCOMMON RES REGION

The classical bacterial site-specific systems of DNA resolution are ch aracterized, despite their considerable divergence, by a regularly arr anged res region represented as a triad of res sites. DNA resolution ( deletion) is carried out more efficiently than DNA inversion, primaril y due to this structure. In this report, the ratio of deletion to inve rsion activities is evaluated for the resolution systems of Tn5053 and Tn402, which belong to a novel family and possess an irregularly arra nged res region. By this criterion, the system studied is shown to be similar to the classical ones. These data suggest that in the course o f evolution of the resolvase systems, the same degree of recombination specialization could be attained by different arrangement of the res region.