DNA-binding and dimerization preferences of Arabidopsis homeodomain-leucine zipper transcription factors in vitro.
Homeodomain-leucine zipper (HDZip) proteins constitute a large family of transcription factors apparently unique to plants. In this report we characterize the DNA-binding and dimerization preferences in vitro of class I HDZip proteins. Using gel-exclusion chromatography and in vitro protein binding assays we demonstrate that the HDZip class I protein ATHB5 forms a homodimeric complex in solution. Consistent with this finding we have demonstrated the sequence-specific interaction of ATHB5 with a 9 bp pseudopalindromic DNA sequence, CAATNATTG, composed of two half-sites overlapping at a central position, by use of a PCR-assisted binding-site selection assay and competitive EMSA experiments. A majority of other known members of HDZip class I interacted with similar DNA sequences, but differed in their preference for A/T versus G/C in the central position of the binding site. Selective heterodimerization in vitro was demonstrated between ATHB5 and different class I HDZip proteins. Heterodimer formation between class I HDZip proteins is of potential functional significance for the integration of information from different signalling pathways in the control of plant development.
Department of Evolutionary Biology, Physiological Botany, Uppsala, Sweden.
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Johannesson
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Wang
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Engström
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D001419:Bacteria / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; C091850:HD-Zip protein, Helianthus annuus; D018398:Homeodomain Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D004247:DNA