Structural studies of DNA gyrase

1984 ◽  
Vol 42 ◽  
pp. 164-167
Author(s):  
T. Kirchhausen ◽  
J. Wang ◽  
S. C. Harrison
Keyword(s):  
Microscopic Study ◽  
Dna Gyrase ◽  
Staphylococcal Nuclease ◽  
Dependent Manner ◽  
Type Ii ◽  
Structural Studies ◽  
Electron Microscopic ◽  
Base Pairs ◽  
Gyrase A ◽  
Negative Supercoils

DNA gyrase, a prokaryotic type II topoisomerase, can introduce negative supercoils into DNA in an ATP-dependent manner and relax negative supercoils in the absence of ATP. Gyrase is a tetramer of two A subunits (MW 105,000) and two B subunits (MW 95,000), and it interacts with about 140 base pairs of DNA (based on staphylococcal nuclease and DNase I protection experiments). We have undertaken an electron microscopic study of gyrase and its binding to DNA, in order to determine how DNA wraps in its complex with the protein.

scholarly journals Molecular Basis for the Differential Quinolone Susceptibility of Mycobacterial DNA Gyrase

2014 ◽  
Vol 58 (4) ◽  
pp. 2013-2020 ◽  
Author(s):  
Rupesh Kumar ◽  
Bhavani Shankar Madhumathi ◽  
Valakunja Nagaraja
Keyword(s):  
Differential Susceptibility ◽  
Dna Gyrase ◽  
Drug Binding ◽  
Double Strand Breaks ◽  
Type Ii ◽  
Content Type ◽  
Strand Breaks ◽  
E Coli ◽  
Dna Complex ◽  
Negative Supercoils

ABSTRACTDNA gyrase is a type II topoisomerase that catalyzes the introduction of negative supercoils in the genomes of eubacteria. Fluoroquinolones (FQs), successful as drugs clinically, target the enzyme to trap the gyrase-DNA complex, leading to the accumulation of double-strand breaks in the genome. Mycobacteria are less susceptible to commonly used FQs. However, an 8-methoxy-substituted FQ, moxifloxacin (MFX), is a potent antimycobacterial, and a higher susceptibility of mycobacterial gyrase to MFX has been demonstrated. Although several models explain the mechanism of FQ action and gyrase-DNA-FQ interaction, the basis for the differential susceptibility of mycobacterial gyrase to various FQs is not understood. We have addressed the basis of the differential susceptibility of the gyrase and revisited the mode of action of FQs. We demonstrate that FQs bind bothEscherichia coliandMycobacterium tuberculosisgyrases in the absence of DNA and that the addition of DNA enhances the drug binding. The FQs bind primarily to the GyrA subunit of mycobacterial gyrase, while inE. coliholoenzyme is the target. The binding of MFX to GyrA ofM. tuberculosiscorrelates with its effectiveness as a better inhibitor of the enzyme and its efficacy in cell killing.

scholarly journals Type II Pneumocytes in Mixed Cell Culture of Human Lung: A Light and Electron Microscopic Study

1990 ◽  
Vol 85 ◽  
pp. 71 ◽  
Author(s):  
Lynne Bingle ◽  
Terence B. Bull ◽  
Bernard Fox ◽  
Abraham Guz ◽  
Roy J. Richards ◽  
...  
Keyword(s):  
Cell Culture ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Human Lung ◽  
Type Ii ◽  
Electron Microscopic ◽  
Mixed Cell ◽  
Type Ii Pneumocytes

The F1 ATP synthetase beta-subunit: a major yeast novobiocin binding protein

1990 ◽  
Vol 96 (4) ◽  
pp. 675-682
Author(s):  
J.R. Jenkins ◽  
M.J. Pocklington ◽  
E. Orr
Keyword(s):  
Cell Death ◽  
Binding Proteins ◽  
Specific Inhibitor ◽  
Dna Gyrase ◽  
Beta Subunit ◽  
Eukaryotic Cells ◽  
Type Ii ◽  
Dna Metabolism ◽  
Subunit A ◽  
Gyrase A

Novobiocin affects DNA metabolism in both prokaryotes and eukaryotes, resulting in cell death. In prokaryotes, the drug is a specific inhibitor of DNA gyrase, a type II topoisomerase that can be purified on a novobiocin-Sepharose column. The yeast type II topoisomerase is neither the biochemical, nor the genetic target of the antibiotic. We have purified the major yeast novobiocin binding proteins and identified one of them as the beta-subunit of the yeast mitochondrial F1 ATP synthetase, a protein highly conserved throughout evolution. The inactivation of this protein might explain the toxic effects of novobiocin on higher eukaryotic cells.

scholarly journals Purification, crystallization and preliminary X-ray crystallographic studies of theMycobacterium tuberculosisDNA gyrase CTD

2012 ◽  
Vol 68 (2) ◽  
pp. 178-180 ◽  
Author(s):  
Amélie Darmon ◽  
Jérémie Piton ◽  
Mélanie Roué ◽  
Stéphanie Petrella ◽  
Alexandra Aubry ◽  
...  
Keyword(s):  
Unique Feature ◽  
Dna Gyrase ◽  
Type Ii ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Unique Type ◽  
X Ray ◽  
His Tag ◽  
Gyrase A ◽  
A Subunit

Mycobacterium tuberculosisDNA gyrase, a nanomachine involved in regulation of DNA topology, is the only type II topoisomerase present in this organism and hence is the sole target of fluoroquinolone in the treatment of tuberculosis. The C-terminal domain (CTD) of the DNA gyrase A subunit possesses a unique feature, the ability to wrap DNA in a chiral manner, that plays an essential role during the catalytic cycle. A construct of 36 kDa corresponding to this domain has been overproduced, purified and crystallized. Diffraction data were collected to 1.55 Å resolution. Cleavage of the N-terminal His tag was crucial for obtaining crystals. The crystals belonged to space groupP212121, with one molecule in the asymmetric unit and a low solvent content (33%). This is the first report of the crystallization and preliminary X-ray diffraction studies of a DNA gyrase CTD from a species that contains one unique type II topoisomerase.

scholarly journals Pentapeptide repeat proteins QnrB1 and AlbG require ATP hydrolysis to rejuvenate poisoned gyrase complexes

2020 ◽  
Author(s):  
Łukasz Mazurek ◽  
Dmitry Ghilarov ◽  
Elizabeth Michalczyk ◽  
Zuzanna Pakosz ◽  
Wojciech Czyszczoń ◽  
...  
Keyword(s):  
Atp Hydrolysis ◽  
Dna Gyrase ◽  
Type Ii ◽  
Site Specific ◽  
Repeat Proteins ◽  
Gyrase A ◽  
Microcin B17 ◽  
Long Term Studies

ABSTRACTDNA gyrase, a type II topoisomerase found predominantly in bacteria, is the target for a variety of “poisons”, namely natural product toxins (e.g. albicidin. microcin B17) and clinically important synthetic molecules (e.g. fluoroquinolones). Resistance to both groups can be mediated by pentapeptide repeat proteins (PRPs). Despite long-term studies, the mechanism of action of these protective PRPs is not known. We compared activities of two such proteins, QnrB1 and AlbG in vitro. Each of them provided specific protection against its cognate toxin (fluoroquinolone or albicidin), which strictly required ATP hydrolysis by gyrase. Through a combination of fluorescence anisotropy, pull-downs and photocrosslinking we show that QnrB1 binds to the GyrB protein. We further probed the QnrB1 binding site using site-specific incorporation of a photoreactive amino acid and mapped strong and specific crosslinks to the N-terminal ATPase/transducer domain. We propose a model in which protective PRPs bind to the enzyme as T-segment DNA mimics to promote dissociation of the bound poison molecule.

Hypothalamic type II iodothyronine deiodinase: a light and electron microscopic study

2003 ◽  
Vol 976 (1) ◽  
pp. 130-134 ◽  
Author(s):  
Sabrina Diano ◽  
Jack L. Leonard ◽  
Rosaria Meli ◽  
Emanuela Esposito ◽  
Luigi Schiavo
Keyword(s):  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Type Ii ◽  
Electron Microscopic ◽  
Iodothyronine Deiodinase
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