Transfection of protoplasts of Bacillus subtilis with phi 29 DNA

Replication of recombinant phi 29 DNA molecules in Bacillus subtilis protoplasts

Recombinant phi 29 DNA molecules of different sizes and containing terminal protein at one or both ends, or without terminal protein, were prepared and their replication in Bacillus subtilis protoplasts was studied. Only phi 29 DNA molecules containing terminal protein at both ends replicate in vivo. The replication of symmetric DNA recombinant molecules (dimers) gives rise to displaced strands which by self-annealing create monomers with the two DNA strands covalently linked. Viral proteins p2, p3, and p6 are essential for replication of phi 29 DNA molecules in this system. Protein p17 is not essential, but stimulates the efficiency of replication. This stimulation depends on the host used.

Phage adsorption and productive lysis in stable protoplast type L-forms of Bacillus subtilis and Streptomyces hygroscopicus

Transferable productive lysis in stable protoplast type L-form cells of Bacillus subtilis was produced by 6 phages out of 14 strains virulent for the parent B. subtilis 170 and 1997. Most of these phages lytic for L-forms show the phi 29 morphology characteristic for the smallest B. subtilis phages containing double-stranded DNA. Among 31 actinophages, 23 of which were virulent for Streptomyces hygroscopicus, only SLE 109 and phi c 31 gave productive infection of the stable protoplast type L-form of S. hygroscopicus NG 33--354. Electron microscopic investigation and treatment by DNAse demonstrated that infection of L-form cells is an adsorption-injection process, and that it is not caused by transfection of free phage DNA or endocytotic uptake of phage particles. Because in both stable L-forms cell wall biosynthesis is blocked irreversibly the results allow the conclusion that specific receptors must be localized in the cytoplasmic membrane for those phages producing transferable lysis in protoplast type L-forms. Localization of receptors for certain phages in the cytoplasmic membrane seems to occur in many Gram-positive bacteria, but not in Gram-negative bacteria.

Nucleotide sequence analysis of DNA replication origins of the small Bacillus bacteriophages: evolutionary relationships

The ends of the small Bacillus phage genomes serve as origins and termini of their DNA replication. We have determined nucleotide sequences at the termini of four different phage DNAs and compared them with those of phi 29 DNA which has been described previously. A high degree of homology was found at the extreme ends of DNAs from phi 29, phi 15 (group A), M2Y and Nf (group B). 17 bp at the far left of the DNAs are identical. A highly conserved dodecanucleotide sequence, CCATTTCCCCAT, was also found in the righthand terminus of all these phage DNAs, at positions 27-38 from the end. Nucleotide sequences of phage GA-1 are not very similar to those of the other phages. Examination of the 5'-terminal and 3'-terminal sequences of all the phages suggests that stable 'panhandle' structures are unlikely to be formed via base pairing of both ends. However, thermodynamically more stable panhandle structures might be formed by displaced single-stranded DNA, although this requires rather large loops.

Transfection of Bacillus subtilis protoplasts by bacteriophage phi do7 DNA

DNA from the Bacillus subtilis temperate bacteriophage phi do7 was found to efficiently transfect B. subtilis protoplasts; protoplast transfection was more efficient than competent cell transfection by a magnitude of 10(3). Unlike competent cell transfection, protoplast transfection did not require primary recombination, suggesting that phi do7 DNA enters the protoplast as double-stranded molecules.