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Polyamines modulate streptomycin-induced mistranslation in Escherichia coli
H G Nastri1, I G Fastame, I D Algranati
1Instituto de Investigaciones Bioquímicas 'Fundación Campomar', Facultad de Ciencias Exactas y Naturales, University of Buenos Aires, Argentina.
Abstract:
The effects of intracellular levels of polyamines on both the in vivo inhibition of protein synthesis and the decrease of translation accuracy induced by streptomycin have been studied in polyamine-auxotrophic strains of Escherichia coli infected with the MS2 bacteriophage. The amount of viral coat protein formed was strongly reduced upon addition of increasing concentrations of streptomycin to polyamine-supplemented bacteria. In contrast, the antibiotic almost did not inhibit coat protein synthesis in polyamine-starved cells. The increase of mistranslation frequency elicited by streptomycin was only observed in bacteria grown with putrescine. In these cells several coat protein-satellites were detected after two-dimensional gel electrophoresis. These proteins, more basic than the normal MS2 coat protein, contain multiple substitutions of lysine for asparagine.
Insights
Polyamines are crucial for bacterial protein synthesis. This study shows streptomycin inhibits protein synthesis and accuracy less in polyamine-starved Escherichia coli, highlighting polyamine
Area of Science:
- Bacteriology
- Molecular Biology
- Genetics
Background:
- Polyamines play a vital role in cellular processes, including protein synthesis and translation fidelity.
- Streptomycin is an antibiotic known to inhibit bacterial protein synthesis and induce translational errors.
- Understanding the interplay between polyamines and streptomycin is essential for deciphering bacterial response mechanisms.
Purpose of the Study:
- To investigate the impact of intracellular polyamine levels on streptomycin-induced inhibition of protein synthesis in Escherichia coli.
- To determine how polyamine availability affects streptomycin's ability to decrease translation accuracy.
- To elucidate the role of specific polyamines, like putrescine, in mediating these effects.
Main Methods:
- Utilized polyamine-auxotrophic strains of Escherichia coli infected with MS2 bacteriophage.
- Administered varying concentrations of streptomycin to bacteria with different polyamine supplementation levels.
- Analyzed viral coat protein synthesis and translation accuracy using techniques like two-dimensional gel electrophoresis.
Main Results:
- Streptomycin significantly inhibited MS2 coat protein synthesis in polyamine-supplemented E. coli.
- This inhibition was markedly reduced in polyamine-starved cells.
- Increased mistranslation frequency by streptomycin was observed only in bacteria grown with putrescine, leading to altered coat proteins.
Conclusions:
- Intracellular polyamine levels critically modulate the effects of streptomycin on bacterial protein synthesis.
- Polyamines, particularly putrescine, are essential for streptomycin to induce significant translational errors.
- These findings provide insights into bacterial resistance mechanisms and antibiotic action.