3no0

Aquifex aeolicus type IIA topoisomerase C-terminal domainAquifex aeolicus type IIA topoisomerase C-terminal domain

Structural highlights 3no0 is a 3 chain structure with sequence from Aquifex aeolicus VF5. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.3004Å Ligands: , Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TOP4A_AQUAE 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). Publication Abstract from PubMed Bacteria frequently possess two type IIA DNA topoisomerases, gyrase and topo IV, which maintain chromosome topology by variously supercoiling, relaxing, and disentangling DNA. DNA recognition and functional output is thought to be controlled by the C-terminal domain (CTD) of the topoisomerase DNA binding subunit (GyrA/ParC). The deeply rooted organism Aquifex aeolicus encodes one type IIA topoisomerase conflictingly categorized as either DNA gyrase or topo IV. To resolve this enzyme's catalytic properties and heritage, we conducted a series of structural and biochemical studies on the isolated GyrA/ParC CTD and the holoenzyme. Whereas the CTD displays a global structure similar to that seen in bone fide GyrA and ParC paralogs, it lacks a key functional motif (the "GyrA-box") and fails to wrap DNA. Biochemical assays show that the A. aeolicus topoisomerase cannot supercoil DNA, but robustly removes supercoils and decatenates DNA, two hallmark activities of topo IV. Despite these properties, phylogenetic analyses place all functional domains except the CTD squarely within a gyrase lineage, and the A. aeolicus GyrB subunit is capable of supporting supercoiling with Escherichia coli GyrA, but not DNA relaxation with E. coli ParC. Moreover, swapping the A. aeolicus GyrA/ParC CTD with the GyrA CTD from Thermotoga maritima creates an enzyme that negatively supercoils DNA. These findings identify A. aeolicus as the first bacterial species yet found to exist without a functional gyrase, and suggest an evolutionary path for generation of bacterial type IIA paralogs. A naturally chimeric type IIA topoisomerase in Aquifex aeolicus highlights an evolutionary path for the emergence of functional paralogs.,Tretter EM, Lerman JC, Berger JM Proc Natl Acad Sci U S A. 2010 Nov 12. PMID:21076033 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Gyrase 3D Structures

spinqualitylabelsall models 3no0, resolution 1.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image