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Endonucleolytic degradation of puf mRNA in Rhodobacter capsulatus is influenced by oxygen

G Klug1

  • 1Zentrum fuer Molekulare Biologie Heidelberg, Federal Republic of Germany.

Proceedings of the National Academy of Sciences of the United States of America
|March 1, 1991
PubMed

Insights

Oxygen levels control pigment-protein complex formation in photosynthetic bacteria by affecting specific messenger RNA (mRNA) degradation. Rhodobacter capsulatus mRNA for photosynthetic components degrades faster under high oxygen, indicating sequence-specific regulation.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Photosynthesis Research

Background:

  • Facultative photosynthetic bacteria regulate pigment-protein complex formation based on environmental oxygen tension.
  • Oxygen levels are known to influence gene expression and protein synthesis in these organisms.

Purpose of the Study:

  • To investigate the impact of oxygen tension on the stability of specific messenger RNA (mRNA) species encoding photosynthetic apparatus components.
  • To identify whether oxygen-regulated mRNA degradation is sequence-dependent.

Main Methods:

  • Comparative analysis of mRNA degradation rates (puf, puc, puhA, cycA, cytfbc) in Rhodobacter capsulatus under varying oxygen tensions (high vs. low).
  • Studies utilizing mutant strains with deletions or insertions in the puf operon to assess the influence of specific genetic regions on mRNA stability.
  • Distinguishing between endonucleolytic and exonucleolytic degradation pathways to understand oxygen's regulatory mechanism.

Main Results:

  • The puf mRNA (reaction center proteins) and puc mRNA (LHII antenna complex proteins) degraded significantly faster under high oxygen tension compared to low oxygen.
  • Rate-limiting endonucleolytic cleavage within the puf mRNA's reaction center coding region was influenced by growth conditions (oxygen tension).
  • mRNA segments degraded via exonucleolytic pathways, and other specific mRNAs (puhA, cycA, cytfbc), showed oxygen-independent degradation rates.

Conclusions:

  • Oxygen tension differentially affects the stability of mRNAs encoding photosynthetic components in Rhodobacter capsulatus.
  • Specific mRNA sequences or structures are crucial determinants of the observed oxygen-dependent mRNA degradation.
  • This regulation provides a mechanism for controlling pigment-protein complex formation in response to environmental oxygen availability.

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