Analysis of the requirement for a pUB110 mob region during Tn916-dependentmobilization

Tn916-de pendent mobilization of nonconjugative plasmids pUB 110 and its de rivative pUB 110 Delta m was compered. Deleting a 787-bp fragment from the pUB110 mob region created plasmid pUB 110 Delta m. Deletion of the mob regi on of pUB110 rendered the plasmid nontransferable by the conjugative plasmi ds of Bacillus thuringiensis subsp, israelensis. During matings between Bac illus subtilis (Tn916) and B. thuringiensis subsp. israelensis, however, Tn 916-dependent mobilization of plasmids pUB110 and pUB110 Delta m was observ ed at a frequency of approximately 2 x 10(-6) transconjugants per donor. Th e results show that Tn916-mediated conjugal transfer of plasmids is a mob-i ndependent event. Jaworski and Clewell (J. Bacteriol 177; 6644-6651) recent ly demonstrated the presence of an IncP-like nicking site in the oriT of Tn 916. These data suggest that a IncP-like nickling site: is essential for Tn 916-mediated plasmid transfer. (C) 1999 Academic Press.