Linked Life Data

11469868

Source:http://linkedlifedata.com/resource/pubmed/id/11469868

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2001-7-25
pubmed:abstractText
The conformational equilibria of the A subunit of DNA gyrase (GyrA), of its 59 kDa N-terminal fragment (GyrA59) and of the quinolone-resistant Ser-Trp83 mutant (GyrATrp83), were investigated in the presence of mono- and divalent metal ions and ciprofloxacin, a clinically useful antibacterial quinolone. The stability of the proteins was estimated from temperature denaturation, monitoring unfolding with circular dichroism spectroscopy. Two transitions were observed in GyrA and GyrATrp83, which likely reflect unfolding of the N and C-terminal protein domains. Accordingly, one thermal transition is observed for GyrA59. The melting profile of the GyrA subunit is dramatically affected by monovalent and divalent metal ions, both transitions being shifted to lower temperature upon increasing salt concentration. This effect is much more pronounced with divalent ions (Mg(2+)) and cannot be accounted for by changes in ionic strength only. The presence of ciprofloxacin shifts the melting transitions of the wild-type subunit to higher temperatures when physiological concentrations of Mg(2+) are present. In contrast, both the mutant protein and the 59 kDa fragment do not show evidence for quinolone-driven changes. These data suggest that ciprofloxacin binds to the wild-type subunit in an interaction that involves Ser83 of GyrA and that both C and N-terminal domains may be required for effective drug-protein interactions. The bell-shaped dependence of the binding process upon Mg(2+) concentration, with a maximum centred at 3-4 mM [Mg(2+)], is consistent with a metal-ion mediated GyrA-quinolone-interaction. Affinity chromatography data fully support these findings and additionally confirm the requirement for a free carboxylate to elicit binding of the quinolone to GyrA. We infer that the Mg(2+)-GyrA interaction at physiological metal ion concentration could bear biological relevance, conferring more conformational flexibility to the active enzyme. The results obtained in the presence of ciprofloxacin additionally suggest that the Mg(2+)-mediated quinolone binding to the enzyme might be involved in the mechanism of action of this family of drugs.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0022-2836
pubmed:author
pubmed:copyrightInfo
Copyright 2001 Academic Press.
pubmed:issnType
Print
pubmed:day
3
pubmed:volume
311
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
195-203
pubmed:dateRevised
2009-11-3
pubmed:meshHeading
pubmed-meshheading:11469868-Amino Acid Substitution, pubmed-meshheading:11469868-Anti-Infective Agents, pubmed-meshheading:11469868-Calcium, pubmed-meshheading:11469868-Cations, Divalent, pubmed-meshheading:11469868-Chromatography, Affinity, pubmed-meshheading:11469868-Ciprofloxacin, pubmed-meshheading:11469868-Circular Dichroism, pubmed-meshheading:11469868-DNA Topoisomerases, Type II, pubmed-meshheading:11469868-Drug Resistance, Microbial, pubmed-meshheading:11469868-Enzyme Stability, pubmed-meshheading:11469868-Magnesium, pubmed-meshheading:11469868-Molecular Weight, pubmed-meshheading:11469868-Mutation, pubmed-meshheading:11469868-Osmolar Concentration, pubmed-meshheading:11469868-Peptide Fragments, pubmed-meshheading:11469868-Protein Conformation, pubmed-meshheading:11469868-Protein Denaturation, pubmed-meshheading:11469868-Protein Folding, pubmed-meshheading:11469868-Protein Subunits, pubmed-meshheading:11469868-Salts, pubmed-meshheading:11469868-Temperature, pubmed-meshheading:11469868-Thermodynamics
pubmed:year
2001
pubmed:articleTitle
Ciprofloxacin affects conformational equilibria of DNA gyrase A in the presence of magnesium ions.
pubmed:affiliation
Department of Pharmaceutical Sciences, University of Padova, via Marzolo 5, Padova, 35100, Italy.
pubmed:publicationType
Journal Article