title: Monomer plasmid DNA transforms Streptococcus pneumoniae.
abstract: The covalently closed (CC) monomer form of plasmid pMV158 was found to transform pneumococcus (Streptococcus pneumoniae) and to do so with two-hit kinetics. The evidence came from analysis of the behavior of the transforming activity in fractions from preparative gel electrophoresis. Activity in the first major peak to elute (i) co-eluted with monomer CC as detected on analytical gels, (ii) banded as CC in dye-buoyancy gradients, (iii) sedimented with the velocity expected for monomer CC, and (iv) gave two-hit kinetics as functions of both concentration and time of exposure of the cells to DNA. A second major peak of activity behaved physically as though mostly due to dimer CC forms and gave single-hit response curves. Because almost no dimer was detectable optically on analytical gels of starting preparations, its specific activity was high relative to that of the monomers.
mesh_terms: D002499:Centrifugation, Density Gradient; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004270:DNA, Circular / Q000235:genetics / Q000302:isolation & purification; D004587:Electrophoresis, Agar Gel; D007700:Kinetics; D010957:Plasmids; D013296:Streptococcus pneumoniae / Q000235:genetics*; D014170:Transformation, Genetic
chemical_list: D004269:DNA, Bacterial; D004270:DNA, Circular