E. coli MukB protein involved in Chromosome partition forms a homodimer with a rod-and-hinge structure having DNA binding and ATP/GTP binding activities

Department of Molecular Cell Biology, Kumamoto University School of Medicine, Japan.
The EMBO Journal (Impact Factor: 10.43). 01/1993; 11(13):5101-9.
Source: PubMed


mukB mutants of Escherichia coli are defective in the correct partitioning of replicated chromosomes. This results in the appearance of normal-sized anucleate (chromosome-less) cells during cell proliferation. Based on the nucleotide sequence of the mukB gene, the MukB protein of 177 kDa was predicted to be a filamentous protein with globular domains at the ends, and also having DNA binding and nucleotide binding abilities. Here we present evidence that the purified MukB protein possesses these characteristics. MukB forms a homodimer with a rod-and-hinge structure having a pair of large, C-terminal globular domains at one end and a pair of small, N-terminal globular domains at the opposite end; it tends to bend at a middle hinge site of the rod section. Chromatography in a DNA-cellulose column and the gel retardation assay revealed that MukB possesses DNA binding activity. Photoaffinity cross-linking experiments showed that MukB binds to ATP and GTP in the presence of Zn2+. Throughout the purification steps, acyl carrier protein was co-purified with MukB.

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    • "Slimfield microscopy can also be used in dual-colour fluorescence microscopy and has been used to study the bacterial SMC proteins in E. coli.[11] SMC proteins have conserved architecture and function across all domains of life with bacteria using a distant relative called MukB with accessory MukE and MukF proteins playing a role in chromosome segregation and organization.[15] [16] Structural and biochemical studies have shown two stoichiometries for the MukBEF complex of 2:4:2 and 2:2:1 (MukB:E:F) dependent on whether ATP is bound or unbound.[17] "
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