title: Actin homolog MreB affects chromosome segregation by regulating topoisomerase IV in Escherichia coli.
abstract: In Escherichia coli, topoisomerase IV, a type II topoisomerase, mediates the resolution of topological linkages between replicated daughter chromosomes and is essential for chromosome segregation. Topo IV activity is restricted to only a short interval late in the cell cycle. However, the mechanism that confers this temporal regulation is unknown. Here we report that the bacterial actin homolog MreB participates in the temporal oscillation of Topo IV activity. We show that mreB mutant strains are deficient in Topo IV activity. In addition, we demonstrate that, depending upon whether it is in a monomeric or polymerized state, MreB affects Topo IV activity differentially. In addition, MreB physically interacts with the ParC subunit of Topo IV. Together, these results may explain how dynamics of the bacterial cytoskeleton are coordinated with the timing of chromosome segregation.
authors.affiliation: Program in Molecular Biology, Weill Graduate School of Cornell University, New York, NY 10065, USA.
authors.forename: Ram
authors.initials: R
authors.lastname: Madabhushi
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Marians
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002453:Cell Cycle; D020090:Chromosome Segregation / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D027101:DNA Topoisomerase IV / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008954:Models, Biological; D009154:Mutation
chemical_list: D000199:Actins; D029968:Escherichia coli Proteins; C078473:MreB protein, E coli; D027101:DNA Topoisomerase IV