TFIIS binds to mouse RNA polymerase I and stimulates transcript elongation and hydrolytic cleavage of nascent rRNA

Mol Gen Genet. 1996 Sep 25;252(4):412-9. doi: 10.1007/BF02173006.


Efficient transcription elongation by RNA polymerase I (Pol I) requires a specific Pol I-associated factor, termed TIF-IC. Here we show that TFIIS, a factor that has previously been shown to promote read-through past many types of blocks to elongation by RNA polymerase II, also enhances Pol I-directed transcription elongation. In a reconstituted transcription system containing purified proteins, TFIIS stimulates Pol I transcription by increasing the overall rate of RNA chain elongation. As with Pol II, ternary Pol I complexes cleave the 3' end of the nascent transcripts in response to TFIIS. The truncated RNAs remain bound to the template, are subject to pyrophosphorolysis, and can be chased into longer transcripts. Moreover, we show by immunoprecipitation and specific affinity chromatography that TFIIS physically interacts with Pol I. The results suggest that nascent transcript cleavage by TFIIS or a TFIIS-related factor may be a general mechanism by which both Pol I and Pol II can bypass transcriptional impediments.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cell-Free System
  • Chromatography, Affinity
  • Hydrolysis
  • Mice
  • Peptide Chain Elongation, Translational
  • Precipitin Tests
  • RNA Polymerase I / genetics*
  • RNA Polymerase I / isolation & purification
  • RNA Polymerase I / metabolism*
  • RNA, Ribosomal / genetics
  • RNA, Ribosomal / metabolism*
  • Trans-Activators / genetics
  • Trans-Activators / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription Factors, General*
  • Transcription, Genetic*
  • Transcriptional Elongation Factors*


  • RNA, Ribosomal
  • Trans-Activators
  • Transcription Factors
  • Transcription Factors, General
  • Transcriptional Elongation Factors
  • transcription factor S-II
  • RNA Polymerase I