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Updated: Jul 2, 2025
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Production of Double-stranded DNA Ministrings
Published on: February 29, 2016
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Loop extrusion-mediated plasmid DNA cleavage by the bacterial SMC Wadjet complex.
Biswajit Pradhan1, Amar Deep2, Jessica König1
1Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany.
Biorxiv : the Preprint Server for Biology
|February 26, 2024
Summary
Wadjet, a bacterial SMC complex, uses DNA loop extrusion to recognize and cleave circular plasmids. This mechanism is crucial for bacterial defense against foreign DNA.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- Structural Maintenance of Chromosomes (SMC) complexes are vital for genome organization in all life forms.
- Bacterial Wadjet complexes, similar to MukBEF, defend against plasmid transformation.
- Previous studies showed Wadjet cleaves circular DNA, but the mechanism was unknown.
Approach:
- Utilized in vitro single-molecule imaging to observe Wadjet's DNA interaction.
- Visualized DNA loop extrusion and plasmid cleavage dynamics.
- Investigated the role of the dimeric JetABC supercomplex and JetC motor subunits.
Key Points:
- Wadjet functions as a symmetric DNA loop extruder, coiling DNA from both sides.
- Loop extrusion requires a dimeric JetABC supercomplex with two JetC motor dimers.
- Wadjet extrudes entire plasmids, stalls, and then cleaves the DNA.
Conclusions:
- DNA loop extrusion is key to Wadjet's plasmid recognition and elimination.
- This study reveals a novel defense mechanism in bacteria.
- Loop extrusion is an evolutionarily conserved process among SMC complexes.
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