Antagonistic signals within the COX2 mRNA coding sequence control its translation in Saccharomyces cerevisiae

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Mitochondrial Transformation in Baker's Yeast to Study Translation and Respiratory Complex Assembly
09:53

Mitochondrial Transformation in Baker's Yeast to Study Translation and Respiratory Complex Assembly

Published on: June 7, 2024

Elizabeth H Williams1, Thomas D Fox

  • 1Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703, USA.

RNA (New York, N.Y.)
|March 22, 2003
PubMed

Insights

Mitochondrial COX2 mRNA translation in yeast is regulated by both positive and negative elements. These elements control the synthesis of cytochrome c oxidase precursor protein (pre-Cox2p) and its assembly.

Area of Science:

  • Mitochondrial Gene Expression
  • Protein Synthesis Regulation
  • Yeast Molecular Biology

Background:

  • Mitochondrial translation of COX2 mRNA in yeast produces the precursor of Cox2p (pre-Cox2p).
  • A previously identified positive element in the COX2 mRNA leader sequence is crucial for reporter gene translation.
  • Cytochrome c oxidase is essential for cellular respiration.

Purpose of the Study:

  • To identify and characterize negative regulatory elements within the COX2 mRNA coding sequence that inhibit translation.
  • To investigate the interplay between positive and negative regulatory elements in COX2 mRNA translation.
  • To explore the role of MRS2 in modulating mitochondrial translation.

Main Methods:

  • Construction and expression of reporter gene fusions with COX2 mRNA sequences in yeast.
  • Localization of negative elements within specific COX2 mRNA codons and predicted stem-loop structures.
  • Analysis of translational inhibition and its antagonism by reintroducing the positive element.
  • Assessment of MRS2 overexpression effects on translational inhibition.

Main Results:

  • Three distinct negative regulatory elements within the COX2 mRNA coding sequence were identified, inhibiting reporter translation.
  • One element functions at the mRNA sequence level (codons 15-25), while two others reside in predicted stem-loop structures (codons 22-44 and 46-74).
  • These inhibitory elements are antagonized by the upstream positive-acting sequence in a sequence-specific manner.
  • MRS2 overexpression partially suppresses individual negative elements but not their combined effect.

Conclusions:

  • The COX2 mRNA coding sequence contains inhibitory elements that regulate pre-Cox2p synthesis.
  • Interplay between positive and negative regulatory signals likely ensures precise timing of pre-Cox2p synthesis and cytochrome c oxidase assembly.
  • Mitochondrial magnesium carrier MRS2 may play a role in modulating translational control.

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