TRANSPOSITIONAL ACTIVITY OF IS986 IN MYCOBACTERIUM-SMEGMATIS

The insertion sequence IS986 (also known as IS6110) has been widely us ed for typing Mycobacterium tuberculosis isolates, due to the extensiv e multiple polymorphism shown using this probe. Although this polymorp hism is presumed to be due to the mobility of IS986, transposition of this element has not previously been demonstrated in the laboratory. U sing artificial composite transposons constructed in a vector unable t o replicate in mycobacteria, we have succeeded in demonstrating the mo bility of IS986 in M. smegmatis, apparently through cointegrate format ion and transposition. The apparently random nature of IS986 insertion s in M. tuberculosis is advantageous for transposon mutagenesis, altho ugh its efficient use will require more effective delivery systems.