title: Phosphorylation-independent binding of 14-3-3 to NtCDPK1 by a new mode.
abstract: 14-3-3 pproteins play essential roles in diverse cellular processes through the direct binding to target proteins. REPRESSION OF SHOOT GROWTH (RSG) is a tobacco (Nicotiana tabacum) transcription factor that is involved in gibberellin (GA) feedback regulation. The 14-3-3 proteins bind to RSG depending on the RSG phosphorylation of Ser-114 and negatively regulate RSG by sequestering it in the cytoplasm in response to GAs. The Ca(2+)-dependent protein kinase NtCDPK1 was identified as an RSG kinase that promotes 14-3-3 binding of RSG by phosphorylation of RSG. 14-3-3 weakly binds to NtCDPK1 by a new mode. The autophosphorylation of NtCDPK1 was necessary for the formation of the binding between NtCDPK1 and 14-3-3 but not for its maintenance. In this study, we showed that 14-3-3 binding to NtCDPK1 does not require the autophosphorylation when RSG was bound to NtCDPK1. These data suggest that 14-3-3 binds to an unphosphorylated motif in NtCDPK1 exposed by a conformational change in NtCDPK1 but not to a phosphate group generated by autophosphorylation of NtCDPK1.
authors.affiliation: a Department of Biological Science; Graduate School of Science ; Hiroshima University; Kagamiyama ; Higashi-Hiroshima , Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ito
authors.forename: Masaru
authors.initials: M
authors.lastname: Nakata
authors.forename: Jutarou
authors.initials: J
authors.lastname: Fukazawa
authors.forename: Sarahmi
authors.initials: S
authors.lastname: Ishida
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D010766:Phosphorylation; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism*; D014026:Nicotiana / Q000201:enzymology / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D010940:Plant Proteins; D011494:Protein Kinases
keywords: CDPK, Ca2+-dependent protein kinase; Ca2+-dependent protein kinase (CDPK); GA, gibberellin.; RSG, repression of shoot growth; calcium; scaffold protein; signal transduction