1s14 | pdb_00001s14
Crystal structure of Escherichia coli Topoisomerase IV ParE 24kDa subunit
Structural highlights
Function[PARE_ECOLI] Topoisomerase IV is essential for chromosome segregation. It relaxes supercoiled DNA. Performs the decatenation events required during the replication of a circular DNA molecule. MukB stimulates the relaxation activity of topoisomerase IV and also has a modest effect on decatenation.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTopoisomerase IV and DNA gyrase are related bacterial type II topoisomerases that utilize the free energy from ATP hydrolysis to catalyze topological changes in the bacterial genome. The essential function of DNA gyrase is the introduction of negative DNA supercoils into the genome, whereas the essential function of topoisomerase IV is to decatenate daughter chromosomes following replication. Here, we report the crystal structures of a 43-kDa N-terminal fragment of Escherichia coli topoisomerase IV ParE subunit complexed with adenylyl-imidodiphosphate at 2.0-A resolution and a 24-kDa N-terminal fragment of the ParE subunit complexed with novobiocin at 2.1-A resolution. The solved ParE structures are strikingly similar to the known gyrase B (GyrB) subunit structures. We also identified single-position equivalent amino acid residues in ParE (M74) and in GyrB (I78) that, when exchanged, increased the potency of novobiocin against topoisomerase IV by nearly 20-fold (to 12 nM). The corresponding exchange in gyrase (I78 M) yielded a 20-fold decrease in the potency of novobiocin (to 1.0 micro M). These data offer an explanation for the observation that novobiocin is significantly less potent against topoisomerase IV than against DNA gyrase. Additionally, the enzyme kinetic parameters were affected. In gyrase, the ATP K(m) increased approximately 5-fold and the V(max) decreased approximately 30%. In contrast, the topoisomerase IV ATP K(m) decreased by a factor of 6, and the V(max) increased approximately 2-fold from the wild-type values. These data demonstrate that the ParE M74 and GyrB I78 side chains impart opposite effects on the enzyme's substrate affinity and catalytic efficiency. Crystal structures of Escherichia coli topoisomerase IV ParE subunit (24 and 43 kilodaltons): a single residue dictates differences in novobiocin potency against topoisomerase IV and DNA gyrase.,Bellon S, Parsons JD, Wei Y, Hayakawa K, Swenson LL, Charifson PS, Lippke JA, Aldape R, Gross CH Antimicrob Agents Chemother. 2004 May;48(5):1856-64. PMID:15105144[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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