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Non-stop mRNA decay initiates at the ribosome

Zhiyun Ge1, Preeti Mehta, Jamie Richards

  • 1Center for Infectious Diseases, Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.

Molecular Microbiology
|November 25, 2010
PubMed

Insights

Cells degrade defective mRNAs lacking stop codons using RNase R, an enzyme recruited to stalled ribosomes. A specific lysine-rich domain on RNase R is crucial for this targeted mRNA decay process.

Area of Science:

  • Molecular Biology
  • RNA Metabolism
  • Protein Synthesis

Background:

  • Messenger RNAs (mRNAs) carry genetic information for protein synthesis.
  • Defective mRNAs without stop codons cause ribosome stalling, hindering cellular function.
  • Cells possess mechanisms to handle aberrant mRNA molecules.

Purpose of the Study:

  • To investigate cellular mechanisms for degrading defective mRNAs lacking stop codons.
  • To identify the role of RNase R in processing non-stop mRNAs.
  • To elucidate the structural requirements for RNase R recruitment and activity.

Main Methods:

  • Studied ribosome stalling induced by non-stop mRNAs.
  • Investigated the recruitment of RNase R to stalled ribosomes.
  • Analyzed the function of RNase R's C-terminal lysine-rich domain.
  • Utilized genetic and biochemical approaches to assess protein and RNA interactions.

Main Results:

  • RNase R is selectively recruited to stalled ribosomes translating non-stop mRNAs.
  • The recruitment and degradation activity depend on SmpB protein and tmRNA.
  • RNase R's C-terminal lysine-rich domain is essential for ribosome engagement and non-stop mRNA decay.
  • The ribosome acts as a platform for initiating non-stop mRNA decay.

Conclusions:

  • RNase R is a key enzyme in the targeted degradation of defective non-stop mRNAs.
  • The ribosome-stalling event triggers a specific RNA degradation pathway involving RNase R.
  • The unique structure of RNase R facilitates its interaction with the translation machinery for efficient mRNA clearance.

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