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Published on: September 12, 2018
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SMC modulates ParB engagement in segregation complexes in streptomyces
Katarzyna Pawlikiewicz1, Agnieszka Strzałka1, Michał Majkowski2
1Department of Molecular Microbiology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland.
Nature Communications
|October 9, 2025
Summary
The SMC protein positively regulates bacterial chromosome segregation by enhancing ParB complex stability and spreading. Its absence reduces ParB dynamics and CTPase activity, impacting DNA segregation.
Area of Science:
- Bacteriology
- Molecular Biology
- Genetics
Background:
- ParB is a bacterial protein crucial for chromosome segregation, possessing CTPase activity.
- ParB forms large nucleoprotein complexes on DNA, recruiting the SMC protein (condensin).
- The role of SMC in modulating ParB complex dynamics and function was previously unknown.
Purpose of the Study:
- To investigate the influence of the SMC protein on the dynamics and stability of ParB-DNA complexes.
- To elucidate the functional relationship between SMC and ParB during bacterial chromosome segregation.
Main Methods:
- Utilized Streptomyces venezuelae strains with and without SMC.
- Employed single-cell time-lapse fluorescence microscopy and single-molecule tracking.
- Conducted fluorescence recovery after photobleaching and chromatin immunoprecipitation assays.
Main Results:
- SMC absence significantly reduced ParB complex stability and spreading along DNA.
- SMC was found to decrease ParB's CTPase activity in vitro.
- ParB mobility on DNA was modulated by the presence of SMC.
Conclusions:
- SMC positively feedbacks on the ParB nucleoprotein complex, enhancing its stability and dynamics.
- SMC plays a critical role in regulating ParB-mediated chromosome segregation.
- These findings provide novel insights into the intricate mechanisms of bacterial chromosome organization.
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