The cloning of plant E2F, a retinoblastoma-binding protein, reveals unique and conserved features with animal G(1)/S regulators.
Association of the retinoblastoma (Rb) protein with E2F transcription factors is central to cell cycle-specific gene expression and growth in animal cells. Whether Rb-E2F complexes are also involved in plant cell growth and differentiation is still unknown since E2F proteins have not yet been identified in plants. Here we report the isolation and characterisation of a wheat E2F (TmE2F) cDNA clone. Interestingly, the overall domain organisation of plant E2F is related to the human E2F-1/2/3 subset but its primary sequence is slightly more related to the E2F-4/5 subset. TmE2F-Rb binding depends on residues, located at the C-terminus, which are different from those of animal E2Fs. However, the acidic or hydrophobic nature of certain residues is maintained, strongly suggesting that they may have a crucial role in E2F activities. Plant E2F is expressed in proliferating cultured cells and in differentiated tissues and is up-regulated early in S phase. Our studies reinforce the idea that G(1)/S regulators in plants are unrelated to those of yeast cells but similar to those of animal cells and provide new tools to analyse the links between cell cycle regulators, plant growth and developmental signals.
Ramírez-Parra
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Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
Xie
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Boniotti
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MB
Gutierrez
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C
D000595:Amino Acid Sequence; D002352:Carrier Proteins; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000032:analysis; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D050704:E2F4 Transcription Factor; D015723:Gene Library; D017343:Genes, Plant; D006801:Humans; D006918:Hydroxyurea / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism*; D056465:Retinoblastoma-Binding Protein 1; D017386:Sequence Homology, Amino Acid; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000235:genetics*; D014908:Triticum / Q000235:genetics*
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D050704:E2F4 Transcription Factor; C493762:E2F4 protein, human; D011993:Recombinant Fusion Proteins; D016160:Retinoblastoma Protein; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D006918:Hydroxyurea