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tmRNA is essential in Shigella flexneri

Nitya S Ramadoss1, Xin Zhou, Kenneth C Keiler

  • 1Pennsylvania State University, Department of Biochemistry & Molecular Biology, University Park, Pennsylvania, United States of America.

Plos One
|March 2, 2013
PubMed

Insights

The trans-translation pathway, involving tmRNA, is vital for Shigella flexneri survival, unlike in E. coli, due to S. flexneri lacking the ArfA backup system. This highlights the general need for nonstop translation complex resolution in bacteria.

Area of Science:

  • Bacteriology
  • Molecular Biology
  • Genetics

Background:

  • Nonstop messenger RNAs (mRNAs) present a translational termination challenge in bacteria.
  • The trans-translation pathway, utilizing tmRNA, resolves stalled ribosomes and nonstop translation complexes.
  • tmRNA is essential in some bacteria, while others possess backup systems like alternative release factor A (ArfA).

Purpose of the Study:

  • To investigate the essentiality of the trans-translation pathway in Shigella flexneri.
  • To determine if S. flexneri possesses a backup system for trans-translation, similar to Escherichia coli.
  • To elucidate the role of tmRNA and ArfA in bacterial viability.

Main Methods:

  • P1 co-transduction experiments were performed to assess tmRNA's essentiality in S. flexneri.
  • Genome sequence analysis was conducted to identify the presence or absence of the ArfA gene in S. flexneri.
  • Functional complementation assays using E. coli ArfA were employed to test its effect on S. flexneri viability.

Main Results:

  • tmRNA was found to be essential for the viability of S. flexneri.
  • Genome analysis revealed that S. flexneri lacks the ArfA gene, unlike E. coli.
  • Introduction of E. coli ArfA into S. flexneri suppressed the essentiality of tmRNA, confirming the absence of a functional backup.

Conclusions:

  • The trans-translation pathway, mediated by tmRNA, is indispensable for S. flexneri survival.
  • S. flexneri's lack of a functional ArfA backup system necessitates tmRNA for resolving nonstop translation complexes.
  • These findings suggest that the resolution of nonstop translation complexes is a critical process for the viability of most bacterial species.

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