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Identification of the region required for monomerization of the rolling circle plasmid pKYM
H Yasukawa1, E Viller, Y Masamune
1Division of Life Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Japan.
Abstract:
Plasmid pKYM, isolated from the gram-negative bacterium Shigella sonnei, is a small multicopy plasmid which replicates by a rolling circle mechanism. The formation of multimers has been observed in a derivative of pKYM which lost a part of the origin region, and the loss of the monomerization mechanism would have led to these multimers. By analyzing the constructs of several mutants, we discovered that a DNA region required for monomerization was present upstream of the RepK binding site in the replication origin. As either of the T-rich sequence or the inverted repeat sequences which were seen in that region have been lost in the multimer-forming plasmids, these sequences may be necessary for monomerization.
Insights
Researchers identified key DNA sequences in the Shigella sonnei plasmid pKYM essential for preventing multimer formation. These sequences, located upstream of the RepK binding site, are crucial for proper plasmid monomerization.
Area of Science:
- Molecular Biology
- Bacteriology
- Genetics
Background:
- The plasmid pKYM from Shigella sonnei is a small, multicopy plasmid replicating via rolling circle mechanism.
- Multimer formation in plasmid derivatives suggests a loss of the monomerization mechanism.
Purpose of the Study:
- To identify the DNA region responsible for monomerization in the pKYM plasmid.
- To understand the role of specific sequences in preventing plasmid multimerization.
Main Methods:
- Analysis of constructs from various pKYM mutants.
- Identification of DNA regions within the replication origin.
Main Results:
- A DNA region upstream of the RepK binding site in the replication origin is required for monomerization.
- Loss of T-rich sequences or inverted repeats in this region correlates with multimer formation.
Conclusions:
- The identified DNA region, potentially involving T-rich and inverted repeat sequences, is critical for pKYM plasmid monomerization.
- Understanding these sequences can aid in controlling plasmid stability and replication.