The replicator region of the Rhizobium leguminosarum cryptic plasmid pRL8JI

The replicator region of the cryptic plasmid pRL8JI from Rhizobium leguminosarum strain 3841 was cloned and sequenced. The recombinant plasmid (pYK3) was selected by function from a partial EcoRI library of total DNA cloned in pSUP202 and shows incompatibility with plasmid pRL8JI when conjugated into R. leguminosarum strains 3841 and its derivative 1062. The cloned insert (approximately 10.5 kb) comprises five EcoRI fragments none of which confers replicative stability when cloned individually. A single 5.0-kb BamHI fragment, that spans all five EcoRI fragments and confers replicative stability on pSUP202 in R. leguminosarum, has been sequenced. This replicator region shows organisational and sequence similarity to the replicator regions of the Agrobacterium plasmids pTiB6S3 and pRiA4b. It has three open reading frames (repA, repB, repC) and a conserved intergenic sequence.