title: Physical and genetic analyses of streptococcal plasmid pAM beta 1 and cloning of its replication region.
abstract: Plasmid pAM beta 1, originally isolated from Streptococcus faecalis DS5, mediates resistance to the MLS (macrolide, lincosamide, and streptogramin B alpha) group of antibiotics. A restriction endonuclease map of the 26.5-kilobase (kb) pAM beta 1 molecule was constructed by using the enzymes AvaI, HpaII, EcoRI, PvuII, Kpn1, BstEII, HpaI, HhaI, and HindIII. A comparison of this map to those of four independently isolated deletion derivatives of pAM beta 1 located the MLS resistance determinant within a 2-kb DNA segment and at least one conjugative function within an 8-kb region. The 5.0-kb EcoRI-B fragment from pAM beta 1 was ligated onto the 4.0-kb Escherichia coli plasmid vector, pACKC1, and used to transform E. coli HB101. The 9.0-kb chimeric plasmid was then used to transform Streptococcus sanguis Challis with concurrent expression of the E. coli kanamycin resistance determinant. The 5.0-kb EcoRI-B fragment from pAM beta 1 was subsequently used as a vector to clone a streptomycin resistance determinant from a strain of Streptococcus mutans containing no detectable plasmid DNA. Subcloning experiments, using a HindIII partial digest of pAM beta 1 DNA, narrowed the replication region of this plasmid to a 2.95-kb fragment.
mesh_terms: D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004261:DNA Replication; D004262:DNA Restriction Enzymes; D013293:Enterococcus faecalis / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D010641:Phenotype; D010957:Plasmids; D013298:Streptococcus sanguis / Q000235:genetics
chemical_list: D004262:DNA Restriction Enzymes