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Artificial RNA Polymerase II Elongation Complexes for Dissecting Co-transcriptional RNA Processing Events
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Distinction and relationship between elongation rate and processivity of RNA polymerase II in vivo

Paul B Mason1, Kevin Struhl

  • 1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.

Molecular Cell
|March 23, 2005
PubMed

Insights

RNA polymerase II (Pol II) elongation rate and processivity in vivo are affected by mutations and drugs. Reduced Pol II elongation leads to dissociation from chromatin, suggesting processivity can be uncoupled from elongation rate.

Area of Science:

  • Molecular Biology
  • Gene Expression
  • Biochemistry

Background:

  • Transcriptional elongation by RNA polymerase II (Pol II) is crucial for gene expression.
  • Factors governing Pol II elongation rate and processivity in vivo remain poorly understood.

Purpose of the Study:

  • To investigate the in vivo effects of mutations and drugs on Pol II elongation rate and processivity.
  • To elucidate the relationship between Pol II elongation rate and processivity.

Main Methods:

  • Analysis of Pol II subunit mutations (Rpb2).
  • Assessment of putative elongation factors, THO complex, and Spt4 mutations.
  • Treatment with drugs 6-azauracil and mycophenolic acid.
  • Investigating combined effects of drugs and mutations (Spt4, TFIIS, CTDK-1).

Main Results:

  • A mutation in the Rpb2 subunit of Pol II reduced both elongation rate and processivity.
  • Putative elongation factors did not affect elongation rate, but THO complex and Spt4 mutations reduced processivity.
  • 6-azauracil and mycophenolic acid decreased both elongation rate and processivity.
  • Drug-induced processivity defects were exacerbated by mutations in Spt4, TFIIS, and CTDK-1.

Conclusions:

  • Reduced Pol II elongation rate in vivo correlates with premature dissociation from the chromatin template.
  • Pol II processivity can be uncoupled from its elongation rate.
  • Elucidation of factors influencing Pol II dynamics during transcription.

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