Studies on the plasmid instability in Corynebacteria.
Recombinant plasmid pNAR4, which can be used as a shuttle vector between E. coli and Coryneform bacteria, was constructed by ligating the DNA fragments of pNAT65 and pACYC184. Plasmid instability was found when pNAR4 was transformed to other Corynebacterium strains, segregational instability in C. crenatum B9 and structural instability in C. glutamicum 10147 and C. crenatum T6-13. When pNAT65 was transformed into C. glutamicum 10147, the plasmids in the transformants were found different from pNAT65. The size and main restriction sites in these plasmids were identical to those of pXZ10145. DNA hybridization indicated that in C. glutamicum 10147 a superhelix DNA was showed higher homology with that in pXZ10145. We assume that the existence of this supercoil DNA is related to the phenomena of various plasmid instability. Inter- or/and intra-molecular recombination may be the reason to explain the related phenomena found in our work.
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Institute of Microbiology, Chinese Academy of Sciences, Beijing.
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Jia
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D003352:Corynebacterium / Q000235:genetics*; D004269:DNA, Bacterial; D004278:DNA, Superhelical / Q000032:analysis; D004926:Escherichia coli / Q000235:genetics; D009693:Nucleic Acid Hybridization; D010957:Plasmids / Q000235:genetics*; D014169:Transformation, Bacterial
D004269:DNA, Bacterial; D004278:DNA, Superhelical