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Initiation-mediated mRNA decay in yeast affects heat-shock mRNAs, and works through decapping and 5'-to-3' hydrolysis

Heather L Heikkinen1, Sara A Llewellyn, Christine A Barnes

  • 1Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5.

Nucleic Acids Research
|July 11, 2003
PubMed

Insights

Initiation-mediated mRNA decay in yeast involves Dcp1 and Xrn1 enzymes and requires ongoing transcription. This pathway specifically degrades heat-shock mRNAs, impacting gene expression under slowed translation initiation.

Area of Science:

  • Molecular Biology
  • Yeast Genetics
  • Gene Regulation

Background:

  • Messenger RNA (mRNA) degradation is crucial for controlling gene expression in Saccharomyces cerevisiae.
  • Multiple mRNA decay pathways exist, including general poly(A)-dependent decay and specialized pathways like nonsense-mediated decay.
  • Initiation-mediated decay (IMD) was previously identified as affecting specific heat-shock mRNAs under slowed translation initiation.

Purpose of the Study:

  • To elucidate the molecular mechanisms of initiation-mediated mRNA decay.
  • To identify the key enzymes and cellular processes involved in IMD.
  • To determine the scope of mRNAs affected by IMD.

Main Methods:

  • Investigated the role of Dcp1 and Xrn1 enzymes in IMD.
  • Assessed the requirement for ongoing transcription by RNA polymerase II in IMD.
  • Analyzed the impact of IMD on various heat-shock and non-heat-shock mRNAs.

Main Results:

  • Initiation-mediated decay utilizes the Dcp1 and Xrn1 enzymes, similar to other decay pathways.
  • IMD is dependent on continuous transcription by RNA polymerase II.
  • Several heat-shock mRNAs, including those from Hsp70 and Hsp90 families, are degraded via IMD, while non-heat-shock mRNAs are unaffected.

Conclusions:

  • Initiation-mediated decay is a distinct mRNA degradation pathway in yeast.
  • IMD contributes to the regulation of heat-shock gene expression.
  • The findings provide new insights into the complex network of mRNA decay in eukaryotes.

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