Specific recognition in gene conversion. The extent of repair synthesis in SPP1 transfection of B. subtilis

Plasmid transformation in Bacillus subtilis: factors affecting the synapsis of donor and recipient DNA

Hybrid plasmids were constructed in which the transcription of regions of inserted DNA was defined. Cells containing these plasmids were transformed with monomeric forms of a different hybrid plasmid, which contained, however, the same inserted DNA as the resident plasmid. The transformation frequencies observed indicated that transcription of homologous DNA in resident plasmids and also tertiary DNA structure interfered with transformation.

Plasmid transformation in Bacillus subtilis. Effects of the insertion of Bacillus subtilis rRNA genes into plasmids

Two HindIII generated DNA fragments of 3.0 and 2.3 Kb derived from rRNA genes of B. subtilis were cloned in E. coli with pBR322. The 3.0 Kb fragment could be subcloned in B. subtilis using pC194. However, only the multimeric, but not the monomeric derivatives of this hybrid plasmid were active in transformation of B. subtilis cells. The 2.3 Kb fragment could neither be subcloned in pC194 nor in pPL603, using both cell and protoplast transformation. We attribute the nonclonability of the 2.3 Kb fragment in B. subtilis to the presence of strong promoter activity in this fragment. Direct proof for the presence of a strong promoter, which is apparently responsible for the transcription of the rRNA gene, was obtained in experiments with B. subtilis and E. coli promoter search plasmids.

The relationship between molecular structure and transformation efficiency of some S. aureus plasmids isolated from B. subtilis

DNA preparations of the chloramphenicol resistance determining S. aureus plasmids pC194, pC223, and PUB112 can be fractionated by gel electrophoresis into various bands. Electronmicroscopic investigations of these various molecular species obtained with pC194 indicated that, depending on the preparations, 70 to 80% of the molecules were monomers, while the rest consisted of various classes of concatemeric and/or interlocked multimers. Measurements of the specific transforming activity of the various molecular classes indicated that the monomers had less than one thousandth the activity of the multimeric plasmic DNA. pC194 DNA of high specific transforming activity could also be obtained by ligation of HindIII generated monomers into concatemeric DNA.

Bacteriophages of Bacillus subtilis

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