Complex formation of MukB, MukE and MukF proteins involved in chromosome partitioning in Escherichia coli. (original) (raw)

• Journal List
• EMBO J
• v.18(21); 1999 Nov 1
• PMC1171653

EMBO J. 1999 Nov 1; 18(21): 5873–5884.

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

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.

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