Autophosphorylation of Ser-6 via an intermolecular mechanism is important for the rapid reduction of NtCDPK1 kinase activity for substrate RSG.

Tobacco (Nicotiana tabacum) Ca2+-dependent protein kinase 1 (NtCDPK1) is involved in feedback regulation of the plant hormone gibberellin through the phosphorylation of the transcription factor, REPRESSION OF SHOOT GROWTH (RSG). Previously, Ser-6 and Thr-21 were identified as autophosphorylation sit...

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Main Authors: Takeshi Ito, Sarahmi Ishida, Yohsuke Takahashi
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2018-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC5912773?pdf=render
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spelling doaj-14d311bdc63547d796cb8e1386ca52162020-11-24T20:41:38ZengPublic Library of Science (PLoS)PLoS ONE1932-62032018-01-01134e019635710.1371/journal.pone.0196357Autophosphorylation of Ser-6 via an intermolecular mechanism is important for the rapid reduction of NtCDPK1 kinase activity for substrate RSG.Takeshi ItoSarahmi IshidaYohsuke TakahashiTobacco (Nicotiana tabacum) Ca2+-dependent protein kinase 1 (NtCDPK1) is involved in feedback regulation of the plant hormone gibberellin through the phosphorylation of the transcription factor, REPRESSION OF SHOOT GROWTH (RSG). Previously, Ser-6 and Thr-21 were identified as autophosphorylation sites in NtCDPK1. Autophosphorylation of Ser-6 and Thr-21 not only decreases the binding affinity of NtCDPK1 for RSG, but also inhibits the homodimerization of NtCDPK1. Furthermore, autophosphorylation decreases the phosphorylation efficiency of RSG. We demonstrated that Ser-6 and Thr-21 of NtCDPK1 are phosphorylated in response to GAs in plants. The substitution of these autophosphorylation sites with Ala enhances the NtCDPK1 overexpression-induced sensitization of seeds to a GA biosynthetic inhibitor during germination. These findings suggested that autophosphorylation of Ser-6 and Thr-21 prevents excessive phosphorylation of RSG. In this study, we attempted to determine which autophosphorylation site is responsible for the functional regulation of NtCDPK1. Ser-6 was autophosphorylated within 1 min, whereas Thr-21 required over 5 min to be completely autophosphorylated. Furthermore, we found that Ser-6 and Thr-21 were autophosphorylated by inter- and intramolecular mechanisms, respectively, which may be reflected in the faster autophosphorylation of Ser-6. Although both autophosphorylation sites were involved in the reduction of the binding affinity of NtCDPK1 for RSG and the inhibition of NtCDPK1 homodimerization, autophosphorylation of Ser-6 alone was sufficient to decrease the kinase activity of NtCDPK1 for RSG. These results suggest that autophosphorylation of Ser-6 is important for the rapid reduction of NtCDPK1 kinase activity for RSG, whereas that of Thr-21 may play an auxiliary role.http://europepmc.org/articles/PMC5912773?pdf=render
collection DOAJ
language English
format Article
sources DOAJ
author Takeshi Ito
Sarahmi Ishida
Yohsuke Takahashi
spellingShingle Takeshi Ito
Sarahmi Ishida
Yohsuke Takahashi
Autophosphorylation of Ser-6 via an intermolecular mechanism is important for the rapid reduction of NtCDPK1 kinase activity for substrate RSG.
PLoS ONE
author_facet Takeshi Ito
Sarahmi Ishida
Yohsuke Takahashi
author_sort Takeshi Ito
title Autophosphorylation of Ser-6 via an intermolecular mechanism is important for the rapid reduction of NtCDPK1 kinase activity for substrate RSG.
title_short Autophosphorylation of Ser-6 via an intermolecular mechanism is important for the rapid reduction of NtCDPK1 kinase activity for substrate RSG.
title_full Autophosphorylation of Ser-6 via an intermolecular mechanism is important for the rapid reduction of NtCDPK1 kinase activity for substrate RSG.
title_fullStr Autophosphorylation of Ser-6 via an intermolecular mechanism is important for the rapid reduction of NtCDPK1 kinase activity for substrate RSG.
title_full_unstemmed Autophosphorylation of Ser-6 via an intermolecular mechanism is important for the rapid reduction of NtCDPK1 kinase activity for substrate RSG.
title_sort autophosphorylation of ser-6 via an intermolecular mechanism is important for the rapid reduction of ntcdpk1 kinase activity for substrate rsg.
publisher Public Library of Science (PLoS)
series PLoS ONE
issn 1932-6203
publishDate 2018-01-01
description Tobacco (Nicotiana tabacum) Ca2+-dependent protein kinase 1 (NtCDPK1) is involved in feedback regulation of the plant hormone gibberellin through the phosphorylation of the transcription factor, REPRESSION OF SHOOT GROWTH (RSG). Previously, Ser-6 and Thr-21 were identified as autophosphorylation sites in NtCDPK1. Autophosphorylation of Ser-6 and Thr-21 not only decreases the binding affinity of NtCDPK1 for RSG, but also inhibits the homodimerization of NtCDPK1. Furthermore, autophosphorylation decreases the phosphorylation efficiency of RSG. We demonstrated that Ser-6 and Thr-21 of NtCDPK1 are phosphorylated in response to GAs in plants. The substitution of these autophosphorylation sites with Ala enhances the NtCDPK1 overexpression-induced sensitization of seeds to a GA biosynthetic inhibitor during germination. These findings suggested that autophosphorylation of Ser-6 and Thr-21 prevents excessive phosphorylation of RSG. In this study, we attempted to determine which autophosphorylation site is responsible for the functional regulation of NtCDPK1. Ser-6 was autophosphorylated within 1 min, whereas Thr-21 required over 5 min to be completely autophosphorylated. Furthermore, we found that Ser-6 and Thr-21 were autophosphorylated by inter- and intramolecular mechanisms, respectively, which may be reflected in the faster autophosphorylation of Ser-6. Although both autophosphorylation sites were involved in the reduction of the binding affinity of NtCDPK1 for RSG and the inhibition of NtCDPK1 homodimerization, autophosphorylation of Ser-6 alone was sufficient to decrease the kinase activity of NtCDPK1 for RSG. These results suggest that autophosphorylation of Ser-6 is important for the rapid reduction of NtCDPK1 kinase activity for RSG, whereas that of Thr-21 may play an auxiliary role.
url http://europepmc.org/articles/PMC5912773?pdf=render
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AT yohsuketakahashi autophosphorylationofser6viaanintermolecularmechanismisimportantfortherapidreductionofntcdpk1kinaseactivityforsubstratersg
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