MukEF Is Required for Stable Association of MukB with the Chromosome

She, Weifeng; Wang, Qinhong; Mordukhova, Elena A.; Rybenkov, Valentin V.

doi:10.1128/jb.00770-07

Cited by 31 publications

(49 citation statements)

References 38 publications

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“…In eukaryotes, Topo II and condensin SMC subunits are abundant components of histone-depleted mitotic chromosomes (69). Similarly, the MukBEF complex remains stably associated with the E. coli chromosome following cell lysis, suggesting that this complex also serves a scaffolding role that organizes the bacterial chromosome into a higher-order structure (71). Electron microscopy studies have revealed that MukBEF complexes can aggregate to form rosettes (72), and high-resolution structural studies suggest that this process may occur through MukF/E mediated bridging of MukB dimers (73).…”

Section: Discussionmentioning

confidence: 99%

Escherichia coli condensin MukB stimulates topoisomerase IV activity by a direct physical interaction

Stewart

Berger

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

139

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In contrast to the current state of knowledge in the field of eukaryotic chromosome segregation, relatively little is known about the mechanisms coordinating the appropriate segregation of bacterial chromosomes. In Escherichia coli , the MukB/E/F complex and topoisomerase IV (Topo IV) are both crucial players in this process. Topo IV removes DNA entanglements following the replication of the chromosome, whereas MukB, a member of the structural maintenance of chromosomes protein family, serves as a bacterial condensin. We demonstrate here a direct physical interaction between the dimerization domain of MukB and the C-terminal domain of the ParC subunit of Topo IV. In addition, we find that MukB alters the activity of Topo IV in vitro. Finally, we isolate a MukB mutant, D692A, that is deficient in its interaction with ParC and show that this mutant fails to rescue the temperature-sensitive growth phenotype of a mukB - strain. These results show that MukB and Topo IV are linked physically and functionally and indicate that the activities of these proteins are not limited to chromosome segregation but likely also play a key role in the control of higher-order bacterial chromosome structure.

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Section: Discussionmentioning

confidence: 99%

Escherichia coli condensin MukB stimulates topoisomerase IV activity by a direct physical interaction

Stewart

Berger

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

139

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“…How then to reconcile the biochemical observations to those in vivo that indicate mukE and mukF mutations have the same phenotype as mukB mutations (33,34), and that MukB ATPbinding and MukEF are required for MukB localization in the cell (11,12)? These observations are not necessarily contradictory.…”

Section: Topological Alteration Of the Dna Observed In The Reactions mentioning

confidence: 99%

“…MukB binds linear and circular DNA in vitro and can induce negative supercoils and knots in relaxed circular DNA in the presence of a topoisomerase (10). Binding of MukB to chromosomal DNA in vivo requires ATP and MukEF (11,12), although MukB DNA binding in vitro does not (10,13).…”

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confidence: 99%

MukB-mediated Catenation of DNA Is ATP and MukEF Independent

Bahng

Hayama

Marians

2016

Journal of Biological Chemistry

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Edited by Patrick SungProperly condensed chromosomes are necessary for accurate segregation of the sisters after DNA replication. The Escherichia coli condesin is MukB, a structural maintenance of chromosomes (SMC)-like protein, which forms a complex with MukE and the kleisin MukF. MukB is known to be able to mediate knotting of a DNA ring, an intramolecular reaction. In our investigations of how MukB condenses DNA we discovered that it can also mediate catenation of two DNA rings, an intermolecular reaction. This activity of MukB requires DNA binding by the head domains of the protein but does not require either ATP or its partner proteins MukE or MukF. The ability of MukB to mediate DNA catenation underscores its potential for bringing distal regions of a chromosome together.The Escherichia coli chromosome is condensed about 1000-fold to fit into the nucleoid of the bacterium. A number of factors contribute to this extreme DNA condensation, among them are: DNA supercoiling, the binding of various nucleoid associated proteins like HU, Fis, and H-NS, and the binding of the structural maintenance of chromosomes (SMC) 3 -like condensin MukBEF (1, 2). SMC proteins act to manage the shape and behavior of chromosomes in both prokaryotes and eukaryotes (3). These proteins dimerize at a hinge region that is flanked by long coiled-coil regions that can be 40 -50 nm in length and that end in head domains that bind and hydrolyze ATP, as well as the bridging kleisin protein (MukF for the E. coli condensin (4)). The kleisin is then itself bound by another protein (MukE for the E. coli condensin (4)). There are three versions of the eukaryotic SMC proteins: the condensin, required for packaging of the chromosomes and comprised of SMC2 and SMC4; the cohesin, required for holding sister chromosomes together during mitosis and comprised of SMC1 and SMC3; and the SMC5-SMC6 complex, required for various aspects of DNA repair (3).It is generally acknowledged that the eukaryotic condensin and cohesin trap DNA topologically in the protein triangle formed by the SMC proteins and the kleisin (5, 6), although an alternative model for DNA binding for the eukaryotic cohesin exists (7). Recent reports suggest that the Bacillus subtilis SMC protein (8) and MukB (9) also trap chromosomes topologically. MukB binds linear and circular DNA in vitro and can induce negative supercoils and knots in relaxed circular DNA in the presence of a topoisomerase (10). Binding of MukB to chromosomal DNA in vivo requires ATP and MukEF (11, 12), although MukB DNA binding in vitro does not (10, 13).We (14) and the Burger and Oakley (15) labs have shown that the MukB hinge region interacts with the C-terminal ␤-propeller region of the ParC subunit of the cellular decatenase topoisomerase IV (Topo IV). We have reported (16) that this interaction stimulates the intramolecular activities of Topo IV, negative supercoil relaxation and knotting, but not the intermolecular activities of Topo IV, catenation/decatenation of DNA rings; whereas Berger, Oakley and colleag...

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“…B. subtilis SMC and its homolog, MukB, in E. coli are composed of two head regions at N and C termini, setting up an ATPase domain separated by two heptad-rich regions forming a single internal long coiled coil that are connected by a flexible hinge domain in the middle. Homodimerized SMC proteins linked by the hinge domain (17) form a complex with ScpA and ScpB (segregation and condensation proteins A and B) (23), while MukB interacts with MukF and MukE in E. coli correspondingly (27). The B. subtilis smc mutant shows a severe temperature-sensitive lethal phenotype with irregular chromosome organization and chromosome segregation defects (4,24).…”

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confidence: 99%