title: Potassium ions are required for nucleotide-induced closure of gyrase N-gate.
abstract: DNA gyrase catalyzes ATP-dependent negative supercoiling of DNA by a strand passage mechanism that requires coordinated opening and closing of three protein interfaces, the N-, DNA-, and C-gates. ATP binding to the GyrB subunits of gyrase causes dimerization and N-gate closure. The closure of the N-gate is a key step in the gyrase catalytic cycle, as it captures the DNA segment to be transported and poises gyrase toward strand passage. We show here that K(+) ions are required for DNA supercoiling but are dispensable for ATP-independent DNA relaxation. Although DNA binding, distortion, wrapping, and DNA-induced narrowing of the N-gate occur in the absence of K(+), nucleotide-induced N-gate closure depends on their presence. Our results provide evidence that K(+) ions relay small conformational changes in the nucleotide-binding pocket to the formation of a tight dimer interface at the N-gate by connecting regions from both GyrB monomers and suggest an important role for K(+) in synchronization of N-gate closure and DNA-gate opening.
authors.affiliation: Institute for Physical Chemistry, University of Münster, D-48149 Münster, Germany. airat.gubaev@uni-muenster.de
authors.forename: Airat
authors.initials: A
authors.lastname: Gubaev
authors.forename: Dagmar
authors.initials: D
authors.lastname: Klostermeier
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000201:enzymology; D027081:DNA Gyrase / Q000737:chemistry* / Q000378:metabolism*; D004278:DNA, Superhelical / Q000737:chemistry / Q000378:metabolism; D004795:Enzyme Stability / Q000187:drug effects; D006868:Hydrolysis / Q000187:drug effects; D008958:Models, Molecular; D011188:Potassium / Q000378:metabolism*; D055503:Protein Multimerization / Q000187:drug effects; D020836:Protein Structure, Quaternary / Q000187:drug effects; D012964:Sodium / Q000378:metabolism
chemical_list: D004278:DNA, Superhelical; D000255:Adenosine Triphosphate; D012964:Sodium; D027081:DNA Gyrase; D011188:Potassium