title: StCDPK3 Phosphorylates In Vitro Two Transcription Factors Involved in GA and ABA Signaling in Potato: StRSG1 and StABF1.
abstract: Calcium-dependent protein kinases, CDPKs, decode calcium (Ca2+) transients and initiate downstream responses in plants. In order to understand how CDPKs affect plant physiology, their specific target proteins must be identified. In tobacco, the bZIP transcription factor Repression of Shoot Growth (NtRSG) that modulates gibberellin (GA) content is a specific target of NtCDPK1. StCDPK3 from potato is homologous (88% identical) to NtCDPK1 even in its N-terminal variable domain. In this work, we observe that NtRSG is also phosphorylated by StCDPK3. The potato RSG family of transcription factors is composed of three members that share similar features. The closest homologue to NtRSG, which was named StRSG1, was amplified and sequenced. qRT-PCR data indicate that StRSG1 is mainly expressed in petioles, stems, lateral buds, and roots. In addition, GA treatment affected StRSG1 expression. StCDPK3 transcripts were detected in leaves, petioles, stolons, roots, and dormant tubers, and transcript levels were modified in response to GA. The recombinant StRSG1-GST protein was produced and tested as a substrate for StCDPK3 and StCDPK1. 6xHisStCDPK3 was able to phosphorylate the potato StRSG1 in a Ca2+-dependent way, while 6xHisStCDPK1 could not. StCDPK3 also interacts and phosphorylates the transcription factor StABF1 (ABRE binding factor 1) involved in ABA signaling, as shown by EMSA and phosphorylation assays. StABF1 transcripts were mainly detected in roots, stems, and stolons. Our data suggest that StCDPK3 could be involved in the cross-talk between ABA and GA signaling at the onset of tuber development.
authors.affiliation: Institute of Genetic Engineering and Molecular Biology (INGEBI), National Research Council (CONICET) Vuelta de Obligado, 2do piso, Buenos Aires, Argentina.
authors.forename: Carolina
authors.initials: C
authors.lastname: Grandellis
authors.affiliation: Institute of Genetic Engineering and Molecular Biology (INGEBI), National Research Council (CONICET) Vuelta de Obligado, 2do piso, Buenos Aires, Argentina.
authors.forename: Elisa
authors.initials: E
authors.lastname: Fantino
authors.affiliation: Institute of Genetic Engineering and Molecular Biology (INGEBI), National Research Council (CONICET) Vuelta de Obligado, 2do piso, Buenos Aires, Argentina.
authors.forename: María Noelia
authors.initials: MN
authors.lastname: Muñiz García
authors.affiliation: Institute of Genetic Engineering and Molecular Biology (INGEBI), National Research Council (CONICET) Vuelta de Obligado, 2do piso, Buenos Aires, Argentina.
authors.forename: Magalí Graciela
authors.initials: MG
authors.lastname: Bialer
authors.affiliation: Institute of Genetic Engineering and Molecular Biology (INGEBI), National Research Council (CONICET) Vuelta de Obligado, 2do piso, Buenos Aires, Argentina.
authors.forename: Franco
authors.initials: F
authors.lastname: Santin
authors.affiliation: Institute of Genetic Engineering and Molecular Biology (INGEBI), National Research Council (CONICET) Vuelta de Obligado, 2do piso, Buenos Aires, Argentina.|Biochemistry Department, School of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina.
authors.forename: Daniela Andrea
authors.initials: DA
authors.lastname: Capiati
authors.affiliation: Institute of Genetic Engineering and Molecular Biology (INGEBI), National Research Council (CONICET) Vuelta de Obligado, 2do piso, Buenos Aires, Argentina.|Biochemistry Department, School of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina.
authors.forename: Rita María
authors.initials: RM
authors.lastname: Ulloa
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics; D020013:Calcium Signaling / Q000235:genetics; D051418:Focal Adhesion Kinase 2 / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism; D010766:Phosphorylation; D010940:Plant Proteins / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics; D012694:Serine; D011198:Solanum tuberosum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: C569999:ABF1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D005875:Gibberellins; D010940:Plant Proteins; C412626:RSG protein, Nicotiana tabacum; D011994:Recombinant Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D012694:Serine; D000040:Abscisic Acid; D051418:Focal Adhesion Kinase 2