Plasmid R394 is a cointegrate

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Plasmids are extrachromosomal DNA elements crucial for bacterial adaptation and evolution.
• Understanding plasmid structure and function is vital for combating antibiotic resistance.
• The behavior of plasmid R394 has presented unexplained anomalies in previous studies.

Purpose of the Study:

• To characterize the individual plasmids R394a and R394b that cointegrate to form R394.
• To elucidate the mechanism behind the cointegration and mobilization of these plasmids.
• To resolve the anomalies observed in the behavior of the composite R394 plasmid.

Main Methods:

• Determination of molecular masses of R394a and R394b using mass spectrometry.
• Incompatibility grouping to assign plasmids to incompatibility groups T and N.
• Assessment of self-transmissibility and mobilization capabilities of each plasmid.

Main Results:

• Plasmids R394a (102 ± 4 MDal) and R394b (11.0 ± 0.4 MDal) were identified.
• R394a belongs to incompatibility group T and R394b to group N.
• R394a is self-transmissible and mobilizes the non-self-transmissible R394b, explaining R394's behavior.

Conclusions:

• The cointegration of R394a and R394b explains the complex behavior of R394.
• These findings clarify previous anomalies and support hypotheses based on variant phages.
• Characterization of R394 provides insights into plasmid interactions and evolution.