Early extracellular events in infection of competent Bacillus subtilis by DNA of bacteriophage SP82G

Temperate Bacillus subtilis bacteriophage phi 3T: chromosomal attachment site and comparison with temperate bacteriophages phi 105 and SPO2

The temperate Bacillus subtilis bacteriophage phi 3T contains within its genome a locus, designated thyP3, that encodes for a protein with thymidylate synthetase activity. Bacteriophage phi 3T is different from the two previously characterized temperate phages, phi 105 and SPO2, in: heteroimmunity, response to bacteriophage antisera, endonuclease digestion pattern, induction in the presence of 6-(p-hydroxyphenylazo)-uracil, and effect on the lytic cycle of bacteriophage phi 1. The mean burst size of phi 3T is 56. The dose response curve with bacteriophage phi 3T DNA is linear for transfection and transformation to the Thy+ phenotype. The inserted prophage has been mapped by PBS1 transduction; it is between chromosomal markers ilvA8 and gltA in the terminus of the chromosome. Thus thyP3 maps at a site separate from, but between, the bacterial markers thyA and thyB when thyP3 is in the prophage state.

Bacteriophages of Bacillus subtilis

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Early stages in DNA binding and uptake during genetic transformation of pneumococci

Ethylenediaminetetraacetate and other divalent-cation-complexing agents greatly stimulate the cellular binding of DNA molecules to competent pneumococci, while the appearance of genetic transformants and nuclease-resistant DNA binding are completely inhibited. Based on this finding, we developed an experimental system in which three early and consecutive stages of genetic transformation can be experimentally separated: (i) attachment of DNA molecules to cell surface sites that are only demonstrable in the competent state; (ii) a divalent-cation-dependent nucleolytic splitting and release of the adsorbed molecules to the medium; and (iii) emergence of potential transformants accompanied by an energy-requiring and divalent-cation-dependent process in which the cell-associated DNA molecules become inaccessible to shearing forces, nucleases, anti-DNA serum, and polycations.

Protease-sensitive transfection of Bacillus subtilis with bacteriophage GA-1 DNA: a probable case of heterologous transfection

The host bacterium of bacteriophage GA-1, Bacillus sp. G1R, was compared with respect to its taxonomic relationship to Bacillus subtilis, B. licheniformis, and B. pumilis. The physiological-biochemical properties of Bacillus sp. G1R are equal to those of B. licheniformis, but the thermal denaturation midpoint of G1R DNA differs by 3 C and the buoyant density by 0.005 g/cm(3) from that of B. licheniformis. Transformation with G1R donor DNA was neither observed in B. licheniformis nor in B. subtilis-competent recipients. Bacteriophage GA-1 shows neither infectivity on B. licheniformis nor on B. subtilis. However, infection of competent B. subtilis cultures with phenol-extracted GA-1 DNA results in the production of infective GA-1 particles. The transfecting activity of GA-1 DNA is destroyed by treatment with proteolytic enzymes. Resistance of transfecting DNA to inactivation by trypsin develops earlier than that to inactivation by DNase. Protease-treated GA-1 DNA competes with transforming DNA to approximately the same extent as does untreated GA-1 DNA, suggesting that uptake of GA-1 DNA is not affected by protease treatment. CsCl density gradient centrifugation reveals that the density of trypsinized GA-1 DNA is 0.004 g/cm(3) greater than that of untreated DNA.

Deoxyribonucleic acid-membrane complexes in the Bacillus subtilis transformation system

The fate of transforming deoxyribonucleic acid (DNA) in Bacillus subtilis was studied by isolating the DNA-membrane complex on Renografin gradients. Soon after uptake, transforming DNA binds to the cell membrane and displays a greater resistance to shear than the recipient genome-membrane complex. Ten minutes after uptake, a portion of the donor DNA is released from the membrane. Most of the released donor radioactivity represents unintegrated, biologically inactive DNA. Recombinant or integrated DNA is enriched 1.5- to 1.7-fold in the membrane. This enrichment last at least 30 min after termination of DNA uptake, and probably much longer. The data suggest that transforming DNA may be integrated into the recipient genome on, or close to, the cell membrane.