Structural highlights
Function
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.[1] [2]
Publication Abstract from PubMed
Chromosome 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[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Li Y, Stewart NK, Berger AJ, Vos S, Schoeffler AJ, Berger JM, Chait BT, Oakley MG. Escherichia coli condensin MukB stimulates topoisomerase IV activity by a direct physical interaction. Proc Natl Acad Sci U S A. 2010 Nov 2;107(44):18832-7. doi:, 10.1073/pnas.1008678107. Epub 2010 Oct 4. PMID:20921377 doi:http://dx.doi.org/10.1073/pnas.1008678107
- ↑ Sawitzke JA, Austin S. Suppression of chromosome segregation defects of Escherichia coli muk mutants by mutations in topoisomerase I. Proc Natl Acad Sci U S A. 2000 Feb 15;97(4):1671-6. PMID:10660686 doi:http://dx.doi.org/10.1073/pnas.030528397
- ↑ Vos SM, Stewart NK, Oakley MG, Berger JM. Structural basis for the MukB-topoisomerase IV interaction and its functional implications in vivo. EMBO J. 2013 Oct 4. doi: 10.1038/emboj.2013.218. PMID:24097060 doi:http://dx.doi.org/10.1038/emboj.2013.218
