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IncFII plasmid incompatibility product and its target are both RNA transcripts
Journal of Bacteriology
|October 1, 1984
Summary
The small leftward RNA transcript of the IncFII plasmid NR1 acts as an incompatibility inhibitor by targeting the rightward mRNA. This interaction regulates repA1 gene expression and plasmid copy number control.
Area of Science:
- Molecular Biology
- Genetics
- Plasmid Biology
Background:
- The IncFII plasmid NR1 contains DNA regions for incompatibility (inc) and copy number control (cop).
- Replication relies on the repA1 protein, transcribed from rightward DNA. A small leftward transcript is also produced.
Purpose of the Study:
- To investigate the role of the small leftward transcript in NR1 plasmid incompatibility.
- To determine the mechanism by which this transcript affects plasmid replication and copy number.
Main Methods:
- Cloning of the DNA fragment encoding the leftward transcript into expression vectors (pBR322, pUC8).
- Varying intracellular levels of rightward and leftward NR1 RNA transcripts in trans.
- Assessing the effects on repA1 gene expression and NR1 plasmid copy number.
Main Results:
- An excess of rightward NR1 RNA stimulated repA1 expression and increased plasmid copy number.
- An excess of leftward NR1 RNA inhibited repA1 expression and decreased plasmid copy number, causing incompatibility.
- A control plasmid without NR1 transcription had no effect.
Conclusions:
- The small leftward transcript functions as the incompatibility inhibitor for NR1 plasmid.
- This inhibitor targets the complementary rightward mRNA, affecting repA1 expression and plasmid maintenance.