title: ABF transcription factors of Thellungiella salsuginea: Structure, expression profiles and interaction with 14-3-3 regulatory proteins.
abstract: ABF transcription factors are the key regulators of ABA signaling. Using RACE-PCR, we identified and sequenced the coding regions of four genes that encode ABF transcription factors in the extremophile plant Thellungiella salsuginea, a close relative of Arabidopsis thaliana that possesses high tolerance to abiotic stresses. An analysis of the deduced amino acid sequences revealed that the similarity between Thellungiella and Arabidopsis ABFs ranged from 71% to 88%. Similar to their Arabidopsis counterparts, Thellungiella ABFs share a bZIP domain and four conservative domains, including a highly conservative motif at the C-terminal tail, which was reported to be a canonical site for binding by 14-3-3 regulatory proteins. Gene expression analysis by real-time PCR revealed a rapid transcript induction of three of the ABF genes in response to salt stress. To check whether Thellungiella ABF transcription factors can interact with abundant 14-3-3 proteins, multiple constructs were designed, and yeast two-hybrid experiments were conducted. Six of the eight tested Ts14-3-3 proteins were able to bind the TsABFs in an isoform-specific manner. A serine-to-alanine substitution in the putative 14-3-3 binding motif resulted in the complete loss of interaction between the 14-3-3 proteins and the ABFs. The role of 14-3-3 interaction with ABFs in the salt and ABA signaling pathways is discussed in the context of Thellungiella survivability.
authors.affiliation: All-Russia Institute of Agricultural Biotechnology; Moscow, Russia.
authors.forename: Denis A
authors.initials: DA
authors.lastname: Vysotskii
authors.affiliation: Department of Molecular Cell Biology; Vrije Universiteit; Amsterdam, The Netherlands.
authors.forename: Ingrid J
authors.initials: IJ
authors.lastname: de Vries-van Leeuwen
authors.affiliation: Department of Molecular Cell Biology; Vrije Universiteit; Amsterdam, The Netherlands.
authors.forename: Erik
authors.initials: E
authors.lastname: Souer
authors.affiliation: All-Russia Institute of Agricultural Biotechnology; Moscow, Russia.
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Babakov
authors.affiliation: Department of Molecular Cell Biology; Vrije Universiteit; Amsterdam, The Netherlands.
authors.forename: Albertus H
authors.initials: AH
authors.lastname: de Boer
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D000040:Abscisic Acid / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics* / Q000378:metabolism; D019607:Brassicaceae / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011485:Protein Binding; D020033:Protein Isoforms; D055049:Salt Tolerance / Q000235:genetics; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; C569999:ABF1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D020033:Protein Isoforms; D014157:Transcription Factors; D000040:Abscisic Acid