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Dissociable Rpb4-Rpb7 subassembly of rna polymerase II binds to single-strand nucleic acid and mediates a post-recruitment step in transcription initiation.

The Rpb4 and Rpb7 subunits of yeast RNA polymerase II form a heterodimeric complex essential for promoter-directed transcription initiation in a reconstituted system. Results of template competition experiments indicate that the Rpb4-Rpb7 complex is not required for stable recruitment of polymerase to active preinitiation complexes, suggesting that Rpb4-Rpb7 mediates an essential step subsequent to promoter binding. Sequence and structure-based alignments revealed a possible OB-fold single-strand nucleic acid-binding motif in Rpb7. Purified Rpb4-Rpb7 complex exhibited both single-strand DNA- and RNA-binding activities, and a small deletion in the putative OB-fold nucleic acid-binding surface of Rpb7 abolished binding activity without affecting the stability of the Rpb4-Rpb7 complex or its ability to associate with polymerase. The same mutation destroyed the transcription activity of the Rpb4-Rpb7 complex. A separate deletion elsewhere in the OB-fold motif of Rpb7 also blocked transcription but did not affect nucleic acid binding, suggesting that the OB-fold of Rpb7 mediates both DNA-protein and protein-protein interactions required for productive initiation.

Pubmed ID: 11087726


  • Orlicky SM
  • Tran PT
  • Sayre MH
  • Edwards AM


The Journal of biological chemistry

Publication Data

March 30, 2001

Associated Grants

  • Agency: NCI NIH HHS, Id: CA73466
  • Agency: NIGMS NIH HHS, Id: GM50724

Mesh Terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Baculoviridae
  • Cell Line
  • DNA, Single-Stranded
  • Dose-Response Relationship, Drug
  • Escherichia coli
  • Gene Deletion
  • Insects
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA Polymerase II
  • Saccharomyces cerevisiae Proteins
  • Sequence Homology, Amino Acid
  • Sulfolobus
  • Transcription, Genetic