The promiscuous plasmids pIP501 and pAM beta 1 from gram-positive bacteria encode complementary resolution functions

pIP501 and pAM beta 1 are promiscuous plasmids from gram-positive bacteria which carry structurally and genetically related replication functions (L. Jannière, A. Gruss and S.D. Ehrlich, 1993, in "Bacillus subtilis and Other Gram-positive Bacteria: Biochemistry, Physiology, and Molecular Genetics (A.L. Sonenshein, J.A. Hoch, and R. Losick, Eds.), pp. 625-644). We report here the sequence of a approximately 1 kb region located downstream of the pIP501 minimal replicon. This region is 82% homologous to the corresponding region of pAM beta 1 and encodes a resolution system which complements that of pAM beta 1. Additionally, we present evidence that the structural similarity between the two plasmids extends for further approximately 2 kb, through a region which may encode a topoisomerase protein in pAM beta 1.