Prolonged environmental stress via a two step process selects mutants of Escherichia, Salmonella and Pseudomonas that grow at 54�C

Droffner, Mary L.; Yamamoto, Nobuto

doi:10.1007/bf00263003

Cited by 20 publications

(11 citation statements)

References 20 publications

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“…The results shown here indicate that the mutations reducing or eliminating topoisomerase I activity can result in increased thermosensitivity in E. coli . This correlates with the findings that mutations in the gyrA gene can lead to increased thermoresistance [8–10]. DNA supercoiling has been shown to be about 12% less negative in one of these gyrA mutants than in the parental strain [10].…”

Section: Discussionsupporting

confidence: 84%

“…There is growing evidence that DNA topoisomerases can influence the ability of bacteria to grow or survive at high temperatures. Involvement of gyrase has emerged from the isolation of a number of thermoresistant mutants of Escherichia coli and S. typhimurium that have been found to have mutations within the gyrA gene for the A subunit of DNA gyrase [8–10]. Among the four promoters utilized for transcription initiation of the topoisomerase I ( topA ) gene of E. coli , the P1 promoter has been shown to be a σ 32 ‐dependent heat shock promoter [11–13].…”

Section: Introductionmentioning

confidence: 99%

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Increased thermosensitivity associated with topoisomerase I deletion and promoter mutations inEscherichia coli

Menzel²,

Tse‐Dinh

1999

FEMS Microbiology Letters

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An Escherichia coli mutant with three of the promoters for the topoisomerase I gene (topA) deleted, such that only the sigma 32-dependent promoter (P1) remained, had a decreased level of topoisomerase I at 30 degrees C and showed increased thermosensitivity at 52 degrees C. However, it could still develop thermotolerance and had a wild-type level of resistance to 52 degrees C treatment if exposed first to 42 degrees C. This indicated that newly synthesized topoisomerase I from transcription initiated at P1 was important for development of thermotolerance. Two other E. coli mutants lacking topA were > 100 times more sensitive to high temperature than their wild-type isogenic strains.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Increased thermosensitivity associated with topoisomerase I deletion and promoter mutations inEscherichia coli

Menzel²,

Tse‐Dinh

1999

FEMS Microbiology Letters

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“…About 10% of the mutations that confer nalidixic acid resistance and map to the locus gyrA confer thermotolerance (Friedman et al 1991). Moreover, mutations in this gene have been previously implicated in adaptation to high temperature (48°C) (Droffner and Yamamoto 1991), so one could expect that some gyrA mutations could be beneficial at high temperature. None of the gyrA mutations studied here showed advantageous effects at 40°C, however that does not preclude an advantage at higher temperatures.…”

Section: Discussionmentioning

confidence: 99%

Antibiotic Resistance and Stress in the Light of Fisher's Model

Trindade¹,

Sousa²,

Gordo³

2012

Evolution

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The role of mutations in evolution depends upon the distribution of their effects on fitness. This distribution is likely to depend on the environment. Indeed genotype‐by‐environment interactions are key for the process of local adaptation and ecological specialization. An important trait in bacterial evolution is antibiotic resistance, which presents a clear case of change in the direction of selection between environments with and without antibiotics. Here, we study the distribution of fitness effects of mutations, conferring antibiotic resistance to Escherichia coli, in benign and stressful environments without drugs. We interpret the distributions in the light of a fitness landscape model that assumes a single fitness peak. We find that mutation effects (s) are well described by a shifted gamma distribution, with a shift parameter that reflects the distance to the fitness peak and varies across environments. Consistent with the theoretical predictions of Fisher's geometrical model, with a Gaussian relationship between phenotype and fitness, we find that the main effect of stress is to increase the variance in s. Our findings are in agreement with the results of a recent meta‐analysis, which suggest that a simple fitness landscape model may capture the variation of mutation effects across species and environments.

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“…With over 2,500 serovars of Salmonella , several have developed the ability to overcome high temperatures allowing for survival through thermal processing; however, this is strain specific (9–11). O’Bryan et al (12) reviewed the thermal resistance of Salmonella species and other foodborne pathogens associated with meat and poultry.…”

Section: Thermal and Non-thermal Stressesmentioning

confidence: 99%

The Potential Link between Thermal Resistance and Virulence in Salmonella: A Review

et al. 2017

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In some animals, the typical body temperature can be higher than humans, for example, 42°C in poultry and 40°C in rabbits which can be a potential thermal stress challenge for pathogens. Even in animals with lower body temperatures, when infection occurs, the immune system may increase body temperature to reduce the chance of survival for pathogens. However, some pathogens can still easily overcome higher body temperatures and/or rise in body temperatures through expression of stress response mechanisms. Salmonella is the causative agent of one of the most prevalent foodborne illnesses, salmonellosis, and can readily survive over a wide range of temperatures due to the efficient expression of the heat (thermal) stress response. Therefore, thermal resistance mechanisms can provide cross protection against other stresses including the non-specific host defenses found within the human body thus increasing pathogenic potential. Understanding the molecular mechanisms associated with thermal responses in Salmonella is crucial in designing and developing more effective or new treatments for reducing and eliminating infection caused by Salmonella that have survived heat stress. In this review, Salmonella thermal resistance is assessed followed by an overview of the thermal stress responses with a focus on gene regulation by sigma factors, heat shock proteins, along with the corresponding thermosensors and their association with virulence expression including a focus on a potential link between heat resistance and potential for infection.

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Prolonged environmental stress via a two step process selects mutants of Escherichia, Salmonella and Pseudomonas that grow at 54�C

Cited by 20 publications

References 20 publications

Increased thermosensitivity associated with topoisomerase I deletion and promoter mutations inEscherichia coli

Increased thermosensitivity associated with topoisomerase I deletion and promoter mutations inEscherichia coli

Antibiotic Resistance and Stress in the Light of Fisher's Model

The Potential Link between Thermal Resistance and Virulence in Salmonella: A Review

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