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Updated: Sep 6, 2025

Inducing a Site Specific Replication Blockage in E. coli Using a Fluorescent Repressor Operator System
Published on: August 21, 2016
DNA sliding and loop formation by E. coli SMC complex: MukBEF
1Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
Abstract:
SMC (structural maintenance of chromosomes) complexes share conserved architectures and function in chromosome maintenance via an unknown mechanism. Here we have used single-molecule techniques to study MukBEF, the SMC complex in Escherichia coli. Real-time movies show MukB alone can compact DNA and ATP inhibits DNA compaction by MukB. We observed that DNA unidirectionally slides through MukB, potentially by a ratchet mechanism, and the sliding speed depends on the elastic energy stored in the DNA. MukE, MukF and ATP binding stabilize MukB and DNA interaction, and ATP hydrolysis regulates the loading/unloading of MukBEF from DNA. Our data suggests a new model for how MukBEF organizes the bacterial chromosome in vivo; and this model will be relevant for other SMC proteins.
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