title: E2Ls, E2F-like repressors of Arabidopsis that bind to E2F sites in a monomeric form.
abstract: E2F transcription factors are major regulators of cell proliferation, and each factor contributes differently to cell cycle control. Arabidopsis contains six E2F homologs, of which three are proteins that exhibit an overall similarity to animal E2Fs and interact with DPa and DPb to stimulate DNA binding. Here we describe the other three E2F-like proteins from Arabidopsis, E2L1-3, which have two copies of a domain with a limited similarity only to the DNA binding domain of E2F. Unlike known E2Fs, the three E2L proteins failed to interact with DPa and DPb and could efficiently bind E2F sites in a monomeric form through the dual-type domain. Transfection assays revealed that E2Ls repress the transcription of reporter genes under the control of E2F-regulated promoters, indicating that E2Ls function to antagonize transactivation mediated by E2F.DP. When fused to green fluorescence protein, E2L1 and E2L3 were predominantly localized to the nucleus whereas E2L2 was detected in both the nucleus and cytoplasm. Because the transcripts of E2Ls were abundant in meristematic rather than fully differentiated tissues, E2Ls may balance the activities of E2F.DP and play a role in restraining cell proliferation.
authors.affiliation: Molecular Genetics Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Kosugi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ohashi
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000737:chemistry; D001665:Binding Sites; D018797:Cell Cycle Proteins; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000737:chemistry; D019281:Dimerization; D050684:E2F Transcription Factors; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; C456300:E2L1 protein, Arabidopsis; C456302:E2L2 protein, Arabidopsis; C456301:E2L3 protein, Arabidopsis; D008164:Luminescent Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins