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A posttranscriptional role for the yeast Paf1-RNA polymerase II complex is revealed by identification of primary

Kristi L Penheiter1, Taylor M Washburn, Stephanie E Porter

  • 1Department of Biochemistry and Molecular Genetics and Molecular Biology Program, University of Colorado, Denver, USA.

Molecular Cell
|October 26, 2005
PubMed

Insights

The yeast Paf1 complex (Paf1C) affects gene expression through post-transcriptional processing, not promoter activity. Loss of Paf1 alters poly(A) site utilization, impacting mRNA abundance and nonsense-mediated decay.

Area of Science:

  • Molecular Biology
  • Yeast Genetics
  • Gene Regulation

Background:

  • The Paf1 complex (Paf1C) associates with RNA Polymerase II (Pol II) at active genes.
  • Loss of Paf1 affects the transcript abundance of only a small subset of genes.

Purpose of the Study:

  • To identify primary and secondary targets of the Paf1C.
  • To understand the mechanism by which Paf1C influences gene expression.

Main Methods:

  • Utilized conditional and null alleles of PAF1.
  • Employed microarray analysis to assess gene expression.
  • Investigated poly(A) site utilization and nonsense-mediated decay (NMD).

Main Results:

  • Neither primary nor secondary Paf1C target promoters responded to Paf1 loss.
  • Paf1 loss altered poly(A) site utilization in SDA1 and MAK21 genes.
  • 3'-extended MAK21 RNA is sensitive to NMD, as shown by increased abundance when Upf1 is absent.

Conclusions:

  • Paf1C-dependent changes in transcript abundance arise from post-transcriptional processing alterations.
  • The Paf1C's role in gene expression is mediated by effects on poly(A) site selection and NMD.
  • Despite association with Pol II during initiation and elongation, Paf1C's impact is post-transcriptional.

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