PMID:10347233
| Citation |
Massé, E and Drolet, M (1999) Relaxation of transcription-induced negative supercoiling is an essential function of Escherichia coli DNA topoisomerase I. J. Biol. Chem. 274:16654-8 |
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| Abstract |
It has been suggested that the essential function of DNA topoisomerase I in Escherichia coli is to prevent chromosomal DNA from reaching an unacceptably high level of global negative supercoiling. However, other in vivo studies have shown that DNA topoisomerase I is very effective in removing local negative supercoiling generated during transcription elongation. To determine whether topoisomerase I is essential for controlling global or local DNA supercoiling, we have prepared a set of topA null mutant strains in combination with different plasmid DNAs. Although we found a correlation between the severity of the growth defect with both transcription-induced and global supercoiling, near to complete growth inhibition correlated only with transcription-induced supercoiling. This result strongly suggests that the major function of DNA topoisomerase I is to relax local negative supercoiling generated during transcription elongation. |
| Links | |
| Keywords |
Antiporters/genetics; Antiporters/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; DNA Topoisomerases, Type I/metabolism; DNA, Bacterial/chemistry; DNA, Bacterial/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli/growth & development; Nucleic Acid Conformation; Promoter Regions, Genetic; Tetracycline Resistance/genetics; Transcription, Genetic |
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