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Regulation of transcription termination in the nematode Caenorhabditis elegans

Simon Haenni1, Helen E Sharpe, Maria Gravato Nobre

  • 1Genetics Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.

Nucleic Acids Research
|September 11, 2009
PubMed

Insights

RNA polymerase II (pol II) transcription termination is not fully understood in operon-like structures. This study reveals cis-splicing of introns in polycistronic pre-mRNAs prevents premature pol II termination in C. elegans.

Area of Science:

  • Molecular Biology
  • Genetics
  • Gene Regulation

Background:

  • Current models for RNA polymerase II (pol II) transcription termination do not fully explain how premature termination is avoided in eukaryotes with operon-like structures.
  • Understanding transcription termination is crucial for comprehending gene expression regulation, especially in complex genomic arrangements.

Purpose of the Study:

  • To investigate transcription termination mechanisms at the end of single-copy genes and genes within operons in Caenorhabditis elegans.
  • To elucidate the role of polycistronic transcription and cis-splicing in preventing premature transcription termination in nematode operons.

Main Methods:

  • Reverse transcription PCR (RT-PCR) to analyze RNA transcripts.
  • Chromatin immunoprecipitation (ChIP) analysis to study protein-DNA interactions.
  • Experimental validation of polycistronic pre-mRNA transcription and cis-splicing in C. elegans operons.

Main Results:

  • RNA polymerase II generally transcribes approximately 1 kb beyond poly(A) sites before terminating in C. elegans.
  • Pol II does not terminate after transcribing internal poly(A) sites within operons.
  • Five randomly selected C. elegans operons were confirmed to be transcribed as single polycistronic pre-mRNAs.
  • Cis-splicing of the first intron in downstream genes of polycistronic pre-mRNAs is essential for their expression.

Conclusions:

  • Transcription termination in C. elegans involves read-through past poly(A) sites.
  • Polycistronic transcription and subsequent cis-splicing of introns in operons are critical for preventing premature RNA polymerase II termination.
  • These findings provide new insights into gene regulation in operon-like structures in eukaryotes.

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