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Mechanism of puf mRNA degradation: the role of an intercistronic stem-loop structure

J G Belasco1, C Y Chen

  • 1Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115.

Gene
|December 10, 1988
PubMed

Insights

The Rhodobacter capsulatus puf operon produces stable pufBA mRNA and unstable pufLMX mRNA. A stem-loop structure protects pufBA mRNA from degradation, acting as an mRNA decay terminator.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Bacterial Genetics

Background:

  • The puf photosynthesis operon in Rhodobacter capsulatus is crucial for light harvesting complex and reaction center production.
  • This operon generates distinct mRNA classes: full-length pufBALMX transcripts and shorter pufBA messages.

Purpose of the Study:

  • To investigate the mechanisms governing the differential stability of puf operon mRNA transcripts.
  • To elucidate the role of the intercistronic stem-loop structure in mRNA processing and decay.

Main Methods:

  • Analysis of mRNA decay rates and patterns in Rhodobacter capsulatus.
  • Identification of cleavage sites and processing intermediates of puf operon transcripts.
  • Structural analysis of the intercistronic region and its impact on RNA stability.

Main Results:

  • Two major mRNA classes were identified: operon-length pufBALMX and shorter pufBA transcripts.
  • The pufBA messages, terminated by a stem-loop, are stable processing products.
  • Decay of pufLMX transcripts initiates via endonucleolytic cleavage downstream of the hairpin.

Conclusions:

  • The intercistronic stem-loop acts as an mRNA decay terminator, stabilizing the upstream pufBA segment.
  • mRNA stability is influenced by the stem-loop's presence and the pufBA segment's resistance to endonucleases.
  • Differential mRNA stability is critical for regulating gene expression in the puf operon.

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