A type II topoisomerase. Despite its similarity to DNA gyrase, this enzyme is not able to supercoil DNA, and instead acts like topoisomerase IV. Relaxes both positively and negatively supercoiled DNA in an ATP-dependent fashion, decatenates interlocked circles. This the first bacteria shown to not contain DNA gyrase, although it has 2 copies of a reverse gyrase that introduces positive supercoils. Type II topoisomerases break and join 2 DNA strands simultaneously in an ATP-dependent manner (PubMed:21076033). ATP-dependent breakage, passage and rejoining of double-stranded DNA. Optimum temperature is 70 degrees Celsius, active between 37 and 90 degrees Celsius. Heterotetramer, composed of two 'GyrA' and two 'GyrB' chains. In the heterotetramer, 'GyrA' contains the active site tyrosine that forms a transient covalent intermediate with the DNA, while 'GyrB' binds cofactors and catalyzes ATP hydrolysis (PubMed:21076033). The C-terminal domain (CTD, residues 494-769) contains 6 tandemly repeated subdomains known as blades, each of which is composed of a 4-stranded antiparallel beta-sheet. The blades form a flat, toroidal beta-pinwheel fold, to which DNA probably binds. Unlike most CTDs, this organism is missing the canonical GyrA-box. The isolated CTD does not impart writhe, DNA wrapping necessary for supercoil introduction. The ability to supercoil DNA is recovered if the CTD is swapped with the CTD of T.maritima (residues 482-804). Belongs to the type II topoisomerase GyrA/ParC subunit family.