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Albert, AC ; Spirito, F ; FigueroaBossi, N ; Bossi, L ; Rahmouni, AR

Hyper-negative template DNA supercoiling during transcription of the tetracycline-resistance gene in topA mutants is largely constrained in vivo

Nucleic Acids Research 24 (15) 3093-3099

par Administrateur - publié le

Abstract :

The excess linking deficit of plasmid DNA from topoisomerase I-defective bacteria (topA mutants) results mainly from transcription and is commonly ascribed to unbalanced relaxation of transcription-induced twin-supercoiled domains. This defect is aggravated in genes for membrane-binding proteins (such as the tet gene) where anchoring of the transcription complex to the bacterial membrane is thought to enhance twin-domain partitioning. Thus, it is often assumed that the ’hyper-negative’ linking difference of plasmid DNA from topA mutants reflects unconstrained, hyper-negative DNA supercoiling inside the cell.