Plasmid deletion formation in recE4 and addB72 mutants of Bacillus subtilis.
Plasmid deletion formation was compared in wild-type, recE4, and addB72 strains of Bacillus subtilis. Deletion frequencies in plasmid pGP1, as monitored with a penP-lacZ fusion, were low in recE4 and high in addB72, in comparison to the wild-type strain. In the wild-type and recE4 strains, deletions between directly repeated sequences were rare. In contrast, about half of the deletions in the addB72 mutant resulted from recombination at direct repeats of 5 bp or more. The sequences at or near the left deletion endpoints showed striking similarities in the three strains. (1) 5'-T-T-T-3', or the complement 5'-A-A-A-3', was frequently located at these sites. (2) 5'-T-G-T-A-3' was found close to most of these termini. (3) Nearly all left termini occurred in a region rich in hyphenated dyad symmetry, which includes the penP transcription/translation regulatory sequences. It is assumed that DNA secondary structures, together with a sequence preference, specify the majority of the left deletion termini, which we speculate to be target sites for topoisomerase I. The right termini of deletions in the wild-type and addB72 mutant were frequently located close to a loose octanucleotide consensus sequence: 5'-G/C-G/C-G/C-G-A/T-A/T-A/T-A/G-3'. In contrast, in the recE4 mutant, the sequence 5'-C-A-G/C-G/C-G/C-G/C-T/G-3' was more frequently found at this position.
Peijnenburg
A C
AC
Department of Genetics, Center of Biological Sciences, Haren (Gn), The Netherlands.
Breed
P V
PV
Bron
S
S
Venema
G
G
D001412:Bacillus subtilis / Q000235:genetics*; D001483:Base Sequence; D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases / Q000235:genetics*; D005798:Genes, Bacterial; D007763:Lac Operon; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010957:Plasmids; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D013728:Terminator Regions, Genetic
D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases; C038225:recE protein, E coli