The first high-mobility-group box of upstream binding factor assembles a cross-over DNA junction by basic residues

Chin Hwa Hu, Ju Ming Wang, Hua Bin Tseng

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Upstream binding factor (UBF) is a eukaryotic RNA polymerase I-specific transcription factor. Its predominant DNA-binding motif, ubfHMG box 1, preserves DNA assembling activity that can bind two or more DNA duplexes simultaneously to form a crossover DNA junction. Here we investigate the basis of crossover DNA-assembling activity of ubfHMG box 1 by extensive mutagenesis analyses and mobility shift assay. Although the ubfHMG box 1 preserves a high mobility group (HMG) core structure, changing a number of the consensus hydrophobic and aromatic residues to alanine did not inhibit its crossover-assembling activity. This indicates that these residues do not directly participate in protein-DNA interaction. However, altering a series of basic residues in the helices 1 and 2 regions or the N-terminal extended strand of the ubfHMG box 1 motif had severe effects on DNA-assembling activity; however, certain non-specific DNA binding activity still remained. This suggests that the ubfHMG box 1 motif might extensively contact the backbone of a crossover junction through its multiple basic residues. Mutating a hydrophobic residue in the terminal dimerization domain inhibited the association of truncated Xenopus UBF, but had little effect on its crossover-assembling activity. This indicates that the UBF-crossover DNA complex is not established by the association of individual DNA-bound peptides.

Original languageEnglish
Pages (from-to)51-56
Number of pages6
JournalBiochemical Journal
Volume333
Issue number1
DOIs
Publication statusPublished - 1998 Jul 1

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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