Stimulation of genetic instability in Streptomyces ambofaciens ATCC 23877 by antibiotics that interact with DNA gyrase.
In wild-type Streptomyces ambofaciens ATCC 23877, pigment-defective (Pig-) mutants arise at a frequency of about 0.5%; this genetic instability is related to genomic rearrangements such as deletions and/or amplifications of DNA sequences. On media containing oxolinic acid and novobiocin, which interact with the A and B subunits of DNA gyrase, respectively, the frequency of variants increased dramatically. The Pig- mutant frequency was increased to almost 100% on a medium containing oxolinic acid at a concentration allowing 55% survival. On solid medium containing either oxolinic acid or novobiocin at subinhibitory concentrations, most colonies exhibited a 'patchwork' phenotype, characterized by the presence of numerous Pig- sectors. Similar phenomena were not observed on media containing the transcriptional inhibitor rifampicin or the translational inhibitor streptomycin. Many of the Pig- mutants exhibited a pleiotropic phenotype and were affected in aerial mycelium formation, colony growth and/or prototrophy. Moreover, the same kinds of rearrangements (deletions and/or amplifications of DNA sequences) were found in both induced and spontaneous Pig- mutants. The results suggest either that DNA gyrase is directly involved in genetic instability or that an SOS-like system is implicated.
Volff
J N
JN
Laboratoire de Génétique et Microbiologie, Faculté des Sciences, Université de Nancy I, France.
Vandewiele
D
D
Simonet
J M
JM
Decaris
B
B
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004250:DNA Topoisomerases, Type II / Q000187:drug effects*; D004269:DNA, Bacterial / Q000187:drug effects* / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D013014:SOS Response, Genetics / Q000187:drug effects; D013302:Streptomyces / Q000187:drug effects* / Q000235:genetics
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004250:DNA Topoisomerases, Type II