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Cell. 1982 Nov;31(1):35-42.

Escherichia coli DNA topoisomerase I mutants: increased supercoiling is corrected by mutations near gyrase genes.

Abstract

Bacterial chromosomes and plasmid (pBR322) DNA from topoisomerase I-defective Escherichia coli strains have been characterized with respect to superhelical density. The topoisomerase I defect results in increased negative superhelical density of both the bacterial chromosome and pBR322. Thus topoisomerase I is involved in determining the level of supercoiling in bacteria. Three of the topoisomerase I-defective strains were studied carry secondary mutations that decrease superhelical density; these additional mutations are closely linked to the gyrB locus in two of the strains and to the gyrA locus in the third strain.

PMID:
6297751
DOI:
10.1016/0092-8674(82)90402-0
[Indexed for MEDLINE]

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