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

Department of Molecular Cell Biology, Kumamoto University School of Medicine, Japan.
The EMBO Journal (Impact Factor: 10.75). 01/1993; 11(13):5101-9.
Source: PubMed

ABSTRACT 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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    • "Strikingly, the STAS domain expressed in E. coli copurified in a 1:1 complex with acyl carrier protein (ACP) and its high-resolution crystal structure revealed a specific interaction between ACP and the STAS domain of YchM. In E. coli, ACP is an abundant 77 residue protein (0.25% of total soluble protein, $5 3 10 4 molecules/cell) that runs anomalously slowly upon SDS-PAGE gels (Byers and Gong, 2007a; Niki et al., 1992). ACP contains a 4 0 -phosphopantetheine group (4 0 -PPa) covalently attached to Ser36 that acts as an activated thiol ester carrier of acyl intermediates during fatty acid biosynthesis (FAB) and other acylation reactions (Byers and Gong, 2007b) such as the biosynthesis of lipid A (Anderson and Raetz, 1987) and phospholipids (Rock and Jackowski, 1982). "
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    • "We examined here DNA bridging by MukBEF. MukBEF plays a key role in organizing the chromosome of Escherichia coli (Niki et al, 1992; Yamanaka et al, 1996; Sawitzke and Austin, 2000; Danilova et al, 2007; She et al, 2007) and is a bacterial prototype of eukaryotic condensins and cohesins. "
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