Related Experiment Videos
Indirect induction of SOS functions in Salmonella typhimurium
Abstract:
Infection of non-UV-irradiated cells of Salmonella typhimurium with UV-damaged P22 or KB1 phage induces recA-dependent inhibition of cell division, cell mutagenesis and prophage induction but not inhibition of respiration. On the contrary, respiration and ATP concentration are increased after treatment with UV-damaged phage in both RecA+ and RecA- strains, showing that this increase is not recA-dependent. Furthermore, infection with UV-damaged phage prevents both inhibition of respiration and decrease in ATP level in the UV-irradiated RecA+ strain. This indirect induction of SOS functions is related to degradation of phage DNA as well as to the multiplicity of infection used, suggesting that DNA degradation may play an important role in the mechanism of expression of the SOS system. Our results give also support to the hypothesis that there exists a differentiation in the expression of the various SOS functions.
Insights
UV-damaged phage infection triggers recA-dependent cell division inhibition and mutagenesis in Salmonella typhimurium. However, respiration and ATP levels increase independently of recA, indicating differentiated SOS function expression.
Area of Science:
- Microbiology
- Molecular Biology
- Bacteriology
Background:
- Bacterial cells possess DNA repair mechanisms, including the SOS response, which is activated by DNA damage.
- Bacteriophages, viruses that infect bacteria, can interact with host cell repair pathways.
- The SOS response involves the RecA protein and regulates various cellular processes.
Purpose of the Study:
- To investigate the effects of UV-damaged phage infection on Salmonella typhimurium cell division, mutagenesis, respiration, and ATP levels.
- To determine the role of the RecA protein in the cellular responses to UV-damaged phage infection.
- To explore the relationship between phage DNA degradation and the induction of SOS functions.
Main Methods:
- Infection of Salmonella typhimurium (RecA+ and RecA- strains) with UV-damaged P22 or KB1 phage.
- Monitoring of cell division, mutagenesis, respiration, and intracellular ATP concentration.
- Analysis of recA-dependent and recA-independent cellular responses.
Main Results:
- UV-damaged phage infection induced recA-dependent inhibition of cell division, mutagenesis, and prophage induction.
- Respiration and ATP levels increased in both RecA+ and RecA- strains, independent of recA.
- Infection with UV-damaged phage protected UV-irradiated cells from respiratory inhibition and ATP decrease.
- Phage DNA degradation and multiplicity of infection influenced SOS function induction.
Conclusions:
- UV-damaged phage infection elicits distinct, recA-dependent and recA-independent cellular responses in Salmonella typhimurium.
- DNA degradation is implicated in the mechanism of SOS system expression.
- Evidence suggests differential regulation and expression of various SOS functions.