title: Complex formation of MukB, MukE and MukF proteins involved in chromosome partitioning in Escherichia coli.
abstract: mukF, mukE and mukB genes are essential for the process of chromosome partitioning in Escherichia coli. We have studied protein-protein interactions among MukB, MukE and MukF proteins by co-immunoprecipitation and sucrose gradient sedimentation experiments, using mukFEB null cells harboring plasmids carrying the wild-type or mutant-type mukFEB operon. MukB forms a complex with MukF and MukE. Analysis of mutant MukB proteins suggested that MukF and MukE bind the C-terminal globular domain of MukB. MukF is indispensable for an interaction between MukB and MukE; however, MukF itself is able to associate with MukB even in the absence of MukE. We have also found that MukF has a Ca(2+)-binding activity. Although purified MukF was able to make a complex either with MukE or MukB, a complex consisting of the three Muk proteins was barely detected in vitro. However, increasing the Ca(2+) or Mg(2+) concentration in the reaction partially restored complex formation. This suggests that Ca(2+) or Mg(2+) may be required for the formation of a complex consisting of the three Muk proteins, and thus may participate in a particular step during chromosome partitioning.
authors.affiliation: Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University School of Medicine, Kuhonji 4-24-1, Kumamoto 862-0976, Japan. yamazoe@gpo.kumamoto-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Yamazoe
authors.forename: T
authors.initials: T
authors.lastname: Onogi
authors.forename: Y
authors.initials: Y
authors.lastname: Sunako
authors.forename: H
authors.initials: H
authors.lastname: Niki
authors.forename: K
authors.initials: K
authors.lastname: Yamanaka
authors.forename: T
authors.initials: T
authors.lastname: Ichimura
authors.forename: S
authors.initials: S
authors.lastname: Hiraga
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D002868:Chromosomal Proteins, Non-Histone; D002875:Chromosomes / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D008274:Magnesium / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D012097:Repressor Proteins; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C067035:MukB protein, E coli; D012097:Repressor Proteins; C087115:mukE protein, E coli; C087116:mukF protein, E coli; D008274:Magnesium; D002118:Calcium