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Nitrosoguanidine-induced adaptive repair in Pseudomonas aeruginosa
S A Rasool1, A Mirza, M A Khan
1Department of Microbiology, University of Karachi, Pakistan.
Abstract:
Error-proof adaptive repair has been demonstrated in Pseudomonas aeruginosa. Cells of actively replicating wild-type Ps. aeruginosa (ATCC27853) and its auxotrophic derivative PAO 286 were subjected to stepwise adaptation (up to 1 microgram ml-1) by nitrosoguanidine (MNNG). Such cells resisted lethal and mutagenic effects of MNNG-challenge (lethal) doses more efficiently than those of nonadapted cultures. Similarly, reactivation of alkylated Pseudomonas phages was enhanced in adapted cells only. Induction of adaptive repair enzymes was sensitive to chloramphenicol (protein synthesis-inhibiting antibiotic) during adaptation treatment only. Protein extract from adapted cells showed increased levels in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE).
Insights
Pseudomonas aeruginosa exhibits error-proof adaptive repair. Adapted cells show enhanced resistance to nitrosoguanidine (MNNG) and improved phage reactivation, indicating a robust protective response.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Pseudomonas aeruginosa possesses DNA repair mechanisms.
- Adaptive responses can enhance bacterial resilience.
- Nitrosoguanidine (MNNG) is a potent mutagen and DNA-damaging agent.
Purpose of the Study:
- To investigate error-proof adaptive repair in Pseudomonas aeruginosa.
- To determine if adaptation enhances resistance to MNNG.
- To explore the effect of adaptation on phage reactivation.
Main Methods:
- Stepwise adaptation of Pseudomonas aeruginosa with MNNG.
- Exposure of adapted and non-adapted cells to lethal MNNG doses.
- Assessing reactivation of alkylated Pseudomonas phages in adapted cells.
- Investigating the role of protein synthesis using chloramphenicol.
- Analyzing protein extracts via SDS-PAGE.
Main Results:
- Adapted Pseudomonas aeruginosa cells demonstrated increased resistance to MNNG's lethal and mutagenic effects.
- Reactivation of alkylated Pseudomonas phages was significantly enhanced in adapted cells.
- The induction of adaptive repair enzymes was dependent on active protein synthesis during adaptation.
- SDS-PAGE revealed increased protein levels in adapted cell extracts.
Conclusions:
- Pseudomonas aeruginosa can develop error-proof adaptive repair mechanisms.
- Adaptation confers enhanced protection against chemical mutagens like MNNG.
- Adaptive repair involves induced protein synthesis and impacts phage biology.