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DNA bending in the mycobacterial plasmid pAL5000 origin-RepB complex
Sujoy Chatterjee1, Arnab Basu, Abhijit Basu
1Bose Institute, Dept. of Microbiology, P1/12 C.I.T. Scheme VIIM, Kolkata 700054, India. sujoy@boseinst.ernet.in
Journal of Bacteriology
|October 2, 2007
Summary
Replication protein RepB binding to Actinomycetes plasmid origins induces DNA bending and looping. This DNA flexibility and RepB multimerization are crucial for plasmid replication initiation.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- Cryptic plasmids like pAL5000 are found in Actinomycetes bacteria.
- Their replication involves a bicistronic operon (repA-repB) encoding replication proteins.
- An origin of replication contains RepB binding sites (L and H) separated by a spacer.
Purpose of the Study:
- To investigate the DNA trajectory in the RepB-origin complex.
- To understand the role of RepB binding in DNA structure and replication.
- To identify novel properties of the RepB protein.
Main Methods:
- Investigated DNA bending and curvature upon RepB binding.
- Analyzed the formation of DNA loops in the RepB-origin complex.
- Characterized the multimerization ability of RepB.
Main Results:
- RepB binding induces significant local DNA bending and long-range polar curvature.
- These deformations facilitate in-phase alignment of binding sites, forming a DNA loop.
- RepB was found to form multimers, potentially influencing DNA trajectory.
Conclusions:
- Actinomycetes plasmid origins are highly flexible.
- Multimeric RepB proteins induce DNA deformations essential for origin function.
- RepB multimerization is a key factor in regulating DNA trajectory and replication.
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