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Influence of RP4 plasmid on extracellular protease secretion by Proteus mirabilis
Abstract:
The transference by conjugation of protease genetic information between Proteus mirabilis strains only occurs upon mobilization by a conjugative plasmid such as RP4 (Inc P group). Upon receiving the RP4 plasmid, the level of proteolytic activity of the protease-excreting P. mirabilis is reduced to about 50%. A similar phenomenon occurs when the protease character is mobilized by the RP4 plasmid from the above transconjugant to a non-protease-excreting recipient strain. The molecular mechanism underlying the interference of R plasmids with proteolytic activity remains to be elucidated but there is evidence suggesting that some alteration in the bacterial envelope might be involved.
Insights
Conjugative plasmids like RP4 mobilize protease gene transfer in Proteus mirabilis. This plasmid transfer significantly reduces proteolytic activity, suggesting bacterial envelope alterations may be involved.
Area of Science:
- Microbiology
- Bacterial genetics
- Molecular biology
Background:
- Protease production in Proteus mirabilis is a key virulence factor.
- Genetic exchange between bacterial strains is often mediated by mobile genetic elements.
- Conjugative plasmids play a crucial role in horizontal gene transfer.
Purpose of the Study:
- To investigate the role of conjugative plasmids in the transfer of protease genetic information between Proteus mirabilis strains.
- To determine the effect of conjugative plasmid mobilization on the proteolytic activity of Proteus mirabilis.
Main Methods:
- Conjugation experiments were performed using Proteus mirabilis strains.
- The conjugative plasmid RP4 (Inc P group) was used for mobilization.
- Proteolytic activity was measured in donor, recipient, and transconjugant strains.
Main Results:
- Protease genetic information transfer occurred only upon mobilization by the conjugative plasmid RP4.
- RP4 plasmid acquisition reduced the proteolytic activity of protease-excreting P. mirabilis by approximately 50%.
- Similar reduction in proteolytic activity was observed when transferring the protease character to a non-protease-excreting strain.
Conclusions:
- Conjugative plasmids, such as RP4, are essential for the mobilization of protease genetic information in Proteus mirabilis.
- The presence of the conjugative plasmid RP4 interferes with or downregulates proteolytic activity in Proteus mirabilis.
- The molecular mechanism of this interference is unknown but may involve alterations in the bacterial envelope.