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TWIN SISTER OF FT (TSF) Interacts with FRUCTOKINASE6 and Inhibits Its Kinase Activity in Arabidopsis

In flowering plants, the developmental switch to the reproductive phase is tightly regulated and involves the integration of internal and external signals. FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF) integrate signals from multiple pathways. FT and TSF function as florigenic substances, and s...

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Autores principales: Jin, Suhyun, Kim, Sun Young, Ahn, Ji Hoon
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5651264/
https://www.ncbi.nlm.nih.gov/pubmed/29093731
http://dx.doi.org/10.3389/fpls.2017.01807
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author Jin, Suhyun
Kim, Sun Young
Ahn, Ji Hoon
author_facet Jin, Suhyun
Kim, Sun Young
Ahn, Ji Hoon
author_sort Jin, Suhyun
collection PubMed
description In flowering plants, the developmental switch to the reproductive phase is tightly regulated and involves the integration of internal and external signals. FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF) integrate signals from multiple pathways. FT and TSF function as florigenic substances, and share high sequence similarity with mammalian Raf kinase inhibitor protein (RKIP). Despite their strong similarity to RKIP, the kinase inhibitory activity of FT and TSF remains to be investigated. We performed a yeast two-hybrid screen and found that TSF interacted with FRUCTOKINASE6 (FRK6), which phosphorylates fructose for various metabolic pathways. Among the seven Arabidopsis FRKs, FRK6 and FRK7 have high sequence similarity; therefore, we investigated whether TSF interacts with FRK6 and FRK7. In vitro pull-down assays and bimolecular fluorescence complementation assays revealed that TSF interacts with FRK6 in the nucleus, but not with FRK7. Kinase activity assays suggested that TSF inhibits the kinase activity of FRK6, whereas FT does not. By contrast, neither TSF nor FT inhibits the kinase activity of FRK7. The frk6 and frk7 mutants show slightly delayed flowering, but only under short-day (SD) conditions. Plastochron length is also affected in both frk6 and frk7 mutants under SD conditions. FT expression levels decreased in frk6 mutants, but not in frk7 mutants. Taken together, our findings suggest that TSF physically interacts with FRK6 and affects its kinase activity, whereas FT does not, although these proteins share high sequence similarity.
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spelling pubmed-56512642017-11-01 TWIN SISTER OF FT (TSF) Interacts with FRUCTOKINASE6 and Inhibits Its Kinase Activity in Arabidopsis Jin, Suhyun Kim, Sun Young Ahn, Ji Hoon Front Plant Sci Plant Science In flowering plants, the developmental switch to the reproductive phase is tightly regulated and involves the integration of internal and external signals. FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF) integrate signals from multiple pathways. FT and TSF function as florigenic substances, and share high sequence similarity with mammalian Raf kinase inhibitor protein (RKIP). Despite their strong similarity to RKIP, the kinase inhibitory activity of FT and TSF remains to be investigated. We performed a yeast two-hybrid screen and found that TSF interacted with FRUCTOKINASE6 (FRK6), which phosphorylates fructose for various metabolic pathways. Among the seven Arabidopsis FRKs, FRK6 and FRK7 have high sequence similarity; therefore, we investigated whether TSF interacts with FRK6 and FRK7. In vitro pull-down assays and bimolecular fluorescence complementation assays revealed that TSF interacts with FRK6 in the nucleus, but not with FRK7. Kinase activity assays suggested that TSF inhibits the kinase activity of FRK6, whereas FT does not. By contrast, neither TSF nor FT inhibits the kinase activity of FRK7. The frk6 and frk7 mutants show slightly delayed flowering, but only under short-day (SD) conditions. Plastochron length is also affected in both frk6 and frk7 mutants under SD conditions. FT expression levels decreased in frk6 mutants, but not in frk7 mutants. Taken together, our findings suggest that TSF physically interacts with FRK6 and affects its kinase activity, whereas FT does not, although these proteins share high sequence similarity. Frontiers Media S.A. 2017-10-18 /pmc/articles/PMC5651264/ /pubmed/29093731 http://dx.doi.org/10.3389/fpls.2017.01807 Text en Copyright © 2017 Jin, Kim and Ahn. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Plant Science
Jin, Suhyun
Kim, Sun Young
Ahn, Ji Hoon
TWIN SISTER OF FT (TSF) Interacts with FRUCTOKINASE6 and Inhibits Its Kinase Activity in Arabidopsis
title TWIN SISTER OF FT (TSF) Interacts with FRUCTOKINASE6 and Inhibits Its Kinase Activity in Arabidopsis
title_full TWIN SISTER OF FT (TSF) Interacts with FRUCTOKINASE6 and Inhibits Its Kinase Activity in Arabidopsis
title_fullStr TWIN SISTER OF FT (TSF) Interacts with FRUCTOKINASE6 and Inhibits Its Kinase Activity in Arabidopsis
title_full_unstemmed TWIN SISTER OF FT (TSF) Interacts with FRUCTOKINASE6 and Inhibits Its Kinase Activity in Arabidopsis
title_short TWIN SISTER OF FT (TSF) Interacts with FRUCTOKINASE6 and Inhibits Its Kinase Activity in Arabidopsis
title_sort twin sister of ft (tsf) interacts with fructokinase6 and inhibits its kinase activity in arabidopsis
topic Plant Science
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5651264/
https://www.ncbi.nlm.nih.gov/pubmed/29093731
http://dx.doi.org/10.3389/fpls.2017.01807
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AT ahnjihoon twinsisteroffttsfinteractswithfructokinase6andinhibitsitskinaseactivityinarabidopsis