Prokaryotic mRNA Degradation
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Questions and Answers

What is the primary function of endoribonucleases in mRNA degradation?

  • To synthesize RNA in the 5' to 3' direction
  • To remove nucleotides from the 3' end of the mRNA
  • To catalyze the internal cleavage of mRNA (correct)
  • To stabilize mRNA by binding to specific sequences

    • Which RNA-binding protein is involved in the processing of ribosomal RNA (rRNA)?

  • RNase III (correct)
  • Hfq
  • RNase E
  • CsrA

    • What is the consequence of deadenylation on mRNA degradation?

  • It removes the secondary structure of the mRNA
  • It increases the translation efficiency of the mRNA
  • It makes the mRNA more susceptible to exonucleases (correct)
  • It stabilizes the mRNA by binding to specific sequences

    • What is a factor that influences mRNA stability?

    <p>The presence of ribosome-binding sites</p> Signup and view all the answers

    Which exoribonuclease is involved in mRNA degradation and can also synthesize RNA in the 3' to 5' direction?

    <p>PNPase</p> Signup and view all the answers

    What is the direction of mRNA degradation catalyzed by RNase R?

    <p>3' to 5'</p> Signup and view all the answers

    What is the primary function of the 5' trifosphate group in procaryotic mRNAs?

    <p>Protection against 5'-3' exonucleases</p> Signup and view all the answers

    What is the consequence of the elimination of pyrophosphate dependent on RppH in the 5' terminal?

    <p>Increased susceptibility to endonucleolytic cleavage</p> Signup and view all the answers

    What is the direction of mRNA degradation catalyzed by exoribonucleases like RNase II, RNase R, and PNPase?

    <p>3' to 5'</p> Signup and view all the answers

    What is the role of RNase E in mRNA degradation?

    <p>Internal endonucleolytic cleavage</p> Signup and view all the answers

    What is the characteristic of the primary transcript produced by procaryotic mRNA synthesis?

    <p>A triphosphate group at the 5' end</p> Signup and view all the answers

    What is the consequence of the activity of RNase E on the 5' monophosphate group?

    <p>Increased susceptibility to exonucleases</p> Signup and view all the answers

    What is the direction of the activity of exoribonucleases like RNase II, RNase R, and PNPase?

    <p>3' to 5'</p> Signup and view all the answers

    What is the role of the 5' trifosphate group in procaryotic mRNAs?

    <p>Protection against 5'-3' exonucleases</p> Signup and view all the answers

    What is the effect of RppH on the stability of procaryotic mRNAs?

    <p>Decreased stability</p> Signup and view all the answers

    What is the function of the stem-loop structure at the 3' end of the primary transcript?

    <p>Protection against exonucleases</p> Signup and view all the answers

    Which process involves the addition of a poly(A) tail and subsequent 3' to 5' degradation of mRNA in E.coli?

    <p>Degradation</p> Signup and view all the answers

    What is the difference in mRNA degradation between E.coli and B.subtilis?

    <p>E.coli uses endonucleases, while B.subtilis uses exonucleases</p> Signup and view all the answers

    What is the consequence of failing to degrade aberrant mRNA products?

    <p>The cell will accumulate aberrant proteins</p> Signup and view all the answers

    What is the role of SmpB-tmRNA in trans-translation?

    <p>To facilitate the degradation of aberrant mRNA products</p> Signup and view all the answers

    What is the purpose of the poly(A) tail in mRNA degradation?

    <p>To mark the mRNA for degradation</p> Signup and view all the answers

    What is the difference between the degradation of mRNA in procaryotes and eukaryotes?

    <p>Procaryotes use endonucleases, while eukaryotes use exonucleases</p> Signup and view all the answers

    What is the consequence of ribosome stalling during translation?

    <p>The ribosomes will become stuck and accumulate</p> Signup and view all the answers

    What is the function of the 3' exonucleases in mRNA degradation?

    <p>To degrade mRNA in the 3' to 5' direction</p> Signup and view all the answers

    What is the significance of the 5' triphosphate group in procaryotic mRNA?

    <p>It marks the mRNA for degradation</p> Signup and view all the answers

    What is the role of the oligoribonuclease in mRNA degradation?

    <p>To degrade mRNA exonucleolytically</p> Signup and view all the answers

    Study Notes

    Prokaryotic mRNA Degradation

    Endoribonucleases

    • Catalyze the internal cleavage of mRNA
    • Create a new 5' end that can be targeted by exoribonucleases
    • Examples:
      • RNase E: a major endoribonuclease involved in mRNA degradation
      • RNase III: involved in the processing of ribosomal RNA (rRNA)

    RNA-binding Proteins

    • Bind to specific sequences or structures on the mRNA
    • Can stabilize or destabilize the mRNA
    • Examples:
      • Hfq: a protein that binds to small RNAs (sRNAs) and helps regulate their activity
      • CsrA: a protein that binds to mRNA and affects its translation and stability

    Deadenylation

    • The removal of the poly(A) tail from the 3' end of the mRNA
    • Can lead to mRNA degradation by making the mRNA more susceptible to exonucleases
    • In prokaryotes, deadenylation is not a major mechanism of mRNA degradation, but it can still occur

    mRNA Stability

    • Influenced by factors such as:
      • Secondary structure of the mRNA
      • Binding of RNA-binding proteins
      • Presence of ribosome-binding sites
      • Translation efficiency
    • mRNAs with shorter half-lives are often degraded more quickly

    Exoribonucleases

    • Catalyze the removal of nucleotides from the 5' or 3' end of the mRNA
    • Can degrade mRNA in a 5' to 3' or 3' to 5' direction
    • Examples:
      • RNase R: a 3' to 5' exoribonuclease involved in mRNA degradation
      • PNPase: a 3' to 5' exoribonuclease that can also synthesize RNA in the 3' to 5' direction

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    Description

    This quiz covers the mechanisms of mRNA degradation in prokaryotes, including the roles of endoribonucleases, RNA-binding proteins, deadenylation, and exoribonucleases in regulating mRNA stability. It also explores the factors that influence mRNA half-life and degradation. Test your knowledge of prokaryotic mRNA degradation pathways!

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