Abstract
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
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Binding Sites
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Blotting, Western
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Chromatography, Gel
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Conserved Sequence
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Crystallography, X-Ray
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DNA, Single-Stranded / chemistry
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DNA, Single-Stranded / genetics
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DNA, Single-Stranded / metabolism*
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DNA-Binding Proteins / chemistry*
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DNA-Binding Proteins / metabolism*
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Electrophoretic Mobility Shift Assay
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Gene Expression Regulation, Plant
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Helix-Loop-Helix Motifs
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Models, Molecular
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Molecular Sequence Data
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Nuclear Proteins / chemistry*
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Nuclear Proteins / metabolism*
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Plant Proteins / chemistry*
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Plant Proteins / metabolism*
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Plants / chemistry*
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Protein Structure, Quaternary
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Protein Structure, Secondary
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Transcription Factors / chemistry*
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Transcription Factors / metabolism*
Substances
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DNA, Single-Stranded
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DNA-Binding Proteins
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Nuclear Proteins
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PBF-2 protein, Solanum tuberosum
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Plant Proteins
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Transcription Factors