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Strand separation establishes a sustained lock at the Tus-Ter replication fork barrier
Bojk A Berghuis1, David Dulin1, Zhi-Qiang Xu2
1Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands.
Nature Chemical Biology
|July 7, 2015
Summary
Bacterial DNA replication requires Tus-Ter protein complexes to prevent replisome collisions. These complexes form a strong lock on nonpermissive DNA, ensuring replication termination and chromosomal integrity.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Bacterial bidirectional DNA replication requires termination to prevent replisome collisions.
- Tus proteins bound to Ter sites in Escherichia coli act as replication termination roadblocks.
Purpose of the Study:
- To investigate the mechanism of Tus-Ter mediated replication termination.
- To determine the role of protein-protein interactions versus DNA-protein interactions in Tus-Ter lock formation.
Main Methods:
- DNA unzipping experiments were used to quantify the strength of the Tus-Ter lock.
- Mutational analysis of Tus protein domains (lock and DNA-binding) was performed.
Main Results:
- Nonpermissively oriented Tus-Ter forms a strong lock, while permissive orientation allows strand separation.
- Lock strength is dependent on the lock domain, not the DNA-binding domain.
- Tus-Ter lock formation is highly specific and efficient in vitro.
Conclusions:
- Tus-Ter complex functions as a highly specific and efficient replication roadblock.
- Protein-protein interactions may not be essential and could potentially hinder lock formation.
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