title: DNA gyrase subunit stoichiometry and the covalent attachment of subunit A to DNA during DNA cleavage.
abstract: Escherichia coli DNA gyrase contains a 1:1 ratio of protomers coded by the genes gyrA and gyrB. This along with previous results shows that the enzyme has two copies of each protomer and thus a molecular weight of 400,000. Abortion of the gyrase reaction results in double-strand breakage of the DNA and covalent attachment of both gyrA protomers to the 5'-cut ends. We conclude that the gyrA protomer contains a critical part of the active site for the concerted breakage and reunion reaction of gyrase, the topoisomerase activity of the enzyme.
mesh_terms: D001665:Binding Sites; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D005796:Genes; D046911:Macromolecular Substances; D008970:Molecular Weight; D009876:Operon; D011485:Protein Binding
chemical_list: D004269:DNA, Bacterial; D046911:Macromolecular Substances; D004250:DNA Topoisomerases, Type II