Interactions of CcdB with DNA Gyrase

Interactions of CcdB with DNA gyrase. Inactivation of Gyra, poisoning of the gyrase-DNA complex, and the antidote action of CcdA.

The F plasmid-carried bacterial toxin, the CcdB protein, is known to act on DNA gyrase in two different ways. CcdB poisons the gyrase-DNA complex, blocking the passage of polymerases and leading to double-strand breakage of the DNA. Alternatively, in cells that overexpress CcdB, the A subunit of DNA gyrase (GyrA) has been found as an inactive complex with CcdB. We have reconstituted the inactiv...

Effect of Qnr on Plasmid Gyrase Toxins CcdB and ParE.

Plasmid toxins CcdB and ParE are part of addiction systems promoting plasmid maintenance. Both target host DNA gyrase, as do quinolones and plasmid-determined Qnr proteins that protect gyrase from quinolone inhibition. We cloned qnrB4, qnrS1, ccdB, parE, and the antitoxin-encoding genes ccdA and parD on compatible plasmids and tested them in combination. CcdB and ParE had no specific effect on ...

A strand-passage conformation of DNA gyrase is required to allow the bacterial toxin, CcdB, to access its binding site

DNA gyrase is the only topoisomerase able to introduce negative supercoils into DNA. Absent in humans, gyrase is a successful target for antibacterial drugs. However, increasing drug resistance is a serious problem and new agents are urgently needed. The naturally-produced Escherichia coli toxin CcdB has been shown to target gyrase by what is predicted to be a novel mechanism. CcdB has been pre...

Positive selection of recombinant DNA by CcdB.

Nature of Lithium Interactions with DNA Nucleobases: Theoretical Study

In the present study, the interactions of three different lithium species Li+, Li3+ and CH3Li with several different sites of the most stable tautomers of DNA nucleo-bases are presented. This investigation is based on the results of thermochemical properties, Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbi...