4mn4
From Proteopedia
Structural Basis for the MukB-topoisomerase IV Interaction
Structural highlights
Function[PARC_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] [4] [MUKB_ECOLI] Plays a central role in chromosome condensation, segregation and cell cycle progression. Functions as a homodimer, which is essential for chromosome partition. Involved in negative DNA supercoiling in vivo, and by this means organizes and compacts chromosomes. May achieve or facilitate chromosome segregation by condensation of DNA from both sides of a centrally located replisome during cell division. Stimulates both DNA relaxation and to a lesser extent decatenation activity of topoisomerase IV.[5] [6] Publication Abstract from PubMedChromosome partitioning in Escherichia coli is assisted by two interacting proteins, topoisomerase (topo) IV and MukB. MukB stimulates the relaxation of negative supercoils by topo IV; to understand the mechanism of their action and to define this functional interplay, we determined the crystal structure of a minimal MukB-topo IV complex to 2.3 A resolution. The structure shows that the so-called 'hinge' region of MukB forms a heterotetrameric assembly with a C-terminal DNA binding domain (CTD) on topo IV's ParC subunit. Biochemical studies show that the hinge stimulates topo IV by competing for a site on the CTD that normally represses activity on negatively supercoiled DNA, while complementation tests using mutants implicated in the interaction reveal that the cellular dependency on topo IV derives from a joint need for both strand passage and MukB binding. Interestingly, the configuration of the MukB.topo IV complex sterically disfavours intradimeric interactions, indicating that the proteins may form oligomeric arrays with one another, and suggesting a framework by which MukB and topo IV may collaborate during daughter chromosome disentanglement. Structural basis for the MukB-topoisomerase IV interaction and its functional implications in vivo.,Vos SM, Stewart NK, Oakley MG, Berger JM EMBO J. 2013 Oct 4. doi: 10.1038/emboj.2013.218. PMID:24097060[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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