Structural Maintenance of Chromosomes (SMC) complexes have ubiquitous roles in compacting DNA linearly, thereby promoting chromosome organization-segregation. Interaction between the Escherichia coli SMC complex, MukBEF, and matS-bound MatP in the chromosome replication termination region, ter, results in depletion of MukBEF from ter, a process essential for efficient daughter chromosome individualisation and for preferential association of MukBEF with the replication origin region. Chromosome-associated MukBEF complexes also interact with topoisomerase IV (ParC2E2), so that their chromosome distribution mirrors that of MukBEF. We demonstrate that MatP and ParC have an overlapping binding interface on the MukB hinge, leading to their mutually exclusive binding, which occurs with the same dimer to dimer stoichiometry. Furthermore, we show that matS DNA competes with the MukB hinge for MatP binding. Cells expressing MukBEF complexes that are mutated at the ParC/MatP binding interface are impaired in ParC binding and have a mild defect in MukBEF function. The data highlight competitive binding as a means of globally regulating MukBEF-topoisomerase IV activity in space and time.
Source data files have been provided for all gel-based figures. Source data files for other assays have been included where indicated. All custom MATLAB scripts are provided as Source Code 1. All code used is previously published and also available via the cited reference(s). All reagents are available upon reasonable request.
- David J Sherratt
- Carol V Robinson
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Maria Spies, University of Iowa, United States
- Received: May 17, 2021
- Accepted: September 21, 2021
- Accepted Manuscript published: September 29, 2021 (version 1)
© 2021, Fisher et al.
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