A new family of plant transcription factors displays a novel ssDNA-binding surface

Nat Struct Biol. 2002 Jul;9(7):512-7. doi: 10.1038/nsb814.


The crystal structure of p24, the single-stranded DNA (ssDNA) binding subunit of the plant defense transcription factor PBF-2, has been determined to 2.3 A resolution. p24 is representative of a novel family of ubiquitous plant-specific proteins that we refer to as the Whirly family because of their quaternary structure. PBF-2 is composed of four p24 molecules that interact through a helix-loop-helix motif. This interaction produces a central pore, with beta-strands radiating outwards, resulting in a whirligig appearance to the quaternary structure. The noncrystallographic C(4) symmetry arrangement of p24 subunits is novel for ssDNA binding proteins and may explain the binding specificity of PBF-2. This structural arrangement also supports the role of PBF-2 in binding melted promoter regions to modulate gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Blotting, Western
  • Chromatography, Gel
  • Conserved Sequence
  • Crystallography, X-Ray
  • DNA, Single-Stranded / chemistry
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / metabolism*
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / metabolism*
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Regulation, Plant
  • Helix-Loop-Helix Motifs
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / metabolism*
  • Plant Proteins / chemistry*
  • Plant Proteins / metabolism*
  • Plants / chemistry*
  • Protein Structure, Quaternary
  • Protein Structure, Secondary
  • Transcription Factors / chemistry*
  • Transcription Factors / metabolism*


  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • Nuclear Proteins
  • PBF-2 protein, Solanum tuberosum
  • Plant Proteins
  • Transcription Factors

Associated data

  • PDB/1L3A