Structure and function of a human transcription factor TFIIIB subunit that is evolutionarily conserved and contains both TFIIB- and high-mobility-group protein 2-related domains

Proc Natl Acad Sci U S A. 1995 Jul 18;92(15):7026-30. doi: 10.1073/pnas.92.15.7026.

Abstract

Transcription factor TFIIIB plays a central role in transcription initiation by RNA polymerase III on genes encoding tRNA, 5S rRNA, and other small structural RNAs. We report the purification of a human TFIIIB-derived complex containing only the TATA-binding polypeptide (TBP) and a 90-kDa subunit (TFIIIB90) and the isolation of a cDNA clone encoding the 90-kDa subunit. The N-terminal half of TFIIIB90 exhibits sequence similarity to the yeast TFIIIB70 (BRF) and the class II transcription factor TFIIB and interacts weakly with TBP. The C-terminal half of TFIIIB90 contains a high-mobility-group protein 2 (HMG2)-related domain and interacts strongly with TBP. Recombinant TFIIIB90 plus recombinant human TBP substitute for human TFIIIB in a complementation assay for transcription of 5S, tRNA, and VA1 RNA genes, and both the TFIIB-related domain and the HMG2-related domain are required for this activity. TFIIIB90 is also required for transcription of human 7SK and U6 RNA genes by RNA polymerase III, but apparently within a complex distinct from the TBP/TFIIIB90 complex.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Biological Evolution
  • Cloning, Molecular
  • Conserved Sequence
  • DNA, Complementary / genetics
  • DNA-Binding Proteins / metabolism
  • Genetic Complementation Test
  • High Mobility Group Proteins / genetics
  • Humans
  • Molecular Sequence Data
  • Protein Binding
  • Protein Conformation
  • RNA, Small Nuclear / biosynthesis
  • Recombinant Proteins / biosynthesis
  • Sequence Homology, Amino Acid
  • TATA-Binding Protein Associated Factors*
  • TATA-Box Binding Protein
  • Transcription Factor TFIIB
  • Transcription Factor TFIIIB
  • Transcription Factors / biosynthesis
  • Transcription Factors / genetics*
  • Transcription Factors / isolation & purification
  • Transcription Factors / metabolism
  • Transcription, Genetic*

Substances

  • BRF1 protein, human
  • DNA, Complementary
  • DNA-Binding Proteins
  • High Mobility Group Proteins
  • RNA, Small Nuclear
  • Recombinant Proteins
  • TATA-Binding Protein Associated Factors
  • TATA-Box Binding Protein
  • Transcription Factor TFIIB
  • Transcription Factor TFIIIB
  • Transcription Factors

Associated data

  • GENBANK/U28838