RNA polymerase-associated transcription specificity factor encoded by vaccinia virus

Byung Yoon Ahn, Bernard Moss

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88 Citations (Scopus)


Vaccinia virus encodes a multisubunit DNA-dependent RNA polymerase (EC that is packaged in the infectious virus particle. This polymerase was found to contain a submolar polypeptide of approximately 85 kDa in addition to the core subunits, which consist of two larger and several smaller polypeptides. The polymerase containing the 85-kDa polypeptide was separated from the core polymerase by column chromatography. Although the core polymerase actively transcribed heterologous single-stranded DNA, only the form with the associated 85-kDa polypeptide could act in conjunction with an early stage-specific factor to transcribe double-stranded DNA containing a vaccinia virus early promoter. Peptide sequencing established that the RNA polymerase-associated 85-kDa protein was derived from the vaccinia virus H4L open reading frame, which encodes a 94-kDa polypeptide that we named RAP94. RAP94 is not closely related to prokaryotic σ70 or eukaryotic RAP30 RNA polymerase-binding proteins, although there are short regions of sequence similarity. The specific association of RAP94 with viral RNA polymerase was corroborated with antibody raised to a recombinant fusion protein. Unlike the previously defined subunits of vaccinia virus RNA polymerase, RAP94 is synthesized exclusively late in infection, and synthesis could be prevented by a DNA replication inhibitor. The role of RAP94 in mediating specific transcription was demonstrated by using an extract from cells in which the H4L open reading frame had been transiently expressed.

Original languageEnglish
Pages (from-to)3536-3540
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number8
Publication statusPublished - 1992


  • Gene expression
  • RAP30 rna polymerase-binding protein
  • RNA polymerase subunit
  • σ factor

ASJC Scopus subject areas

  • General


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