ATYPICAL DELETIONS GENERATED BY MUTATED IS102 ELEMENTS

The [bacterial] element insertion sequence IS102 potentially codes for 2 polypeptide chains. Several mutations were introduced in the larger one near the COOH terminus and determined the residual ability of the mutated elements to generate deletions in order to assign a role to this polypeptide chain. In these elements, deletions still occur, although at a reduced level, but in all cases examined so far the ends of the element are no longer recognized as the fixed endpoint of IS-mediated deletions, even though some other structural features of normal deletion formation are still present.