[Effect of a fragment of pBR322 plasmid in the region of tetracycline resistance gene on the stability of this plasmid].

A fragment destabilizing the pBR322 plasmid has been localized in the region of pBR322 tet gene promoter. On the basis of stability analysis of pBR322 derivatives comprising the modified region of tet gene, we deduced that it is the DNA sequence localized at the beginning of tet gene in the region of HindIII splitting site that ensures the plasmid destabilization, and not tet gene product or the active transcription of this region. The destabilizing effect of this fragment of the plasmid is manifested both in cis and in trans. Possible molecular mechanisms of the phenomenon are discussed.