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A single DnaA box is sufficient for initiation from the P1 plasmid origin
A L Abeles1, L D Reaves, S J Austin
1Laboratory of Chromosome Biology, National Cancer Institute-Frederick Cancer Research and Development Center, Maryland 21701.
Journal of Bacteriology
|August 1, 1990
Summary
The P1 plasmid replication origin uses DnaA protein. Its function depends on DnaA-binding boxes, which show flexibility in number and position, unlike the host oriC origin.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- The P1 plasmid replication origin is essential for plasmid propagation.
- Host DnaA protein is a key regulator of DNA replication initiation.
- DnaA-binding boxes are critical elements within replication origins.
Purpose of the Study:
- To investigate the functional role and positional flexibility of DnaA-binding boxes in the P1 plasmid replication origin.
- To compare the P1 origin's DnaA-binding box requirements with those of the host oriC origin.
Main Methods:
- Construction and functional analysis of P1 origin variants with altered DnaA-binding box configurations.
- Assessing origin activity through replication assays.
- Sequence analysis to determine the importance of consensus DnaA-binding sequences.
Main Results:
- Both sets of DnaA-binding boxes (left and right) are functional independently for P1 origin activity.
- A single consensus DnaA-binding box is sufficient for origin function, irrespective of its position relative to core origin sequences.
- One of the two origin-proximal boxes exhibits reduced activity.
Conclusions:
- The P1 plasmid replication origin exhibits significant flexibility in the number and positioning of DnaA-binding boxes.
- This flexibility suggests a distinct regulatory mechanism compared to the more constrained host oriC origin.
- The precise consensus sequence of a DnaA-binding box is crucial for its function in P1 plasmid replication.