Tobacco Calcium-dependent Protein Kinases Are Differentially Phosphorylated in Vivo as Part of a Kinase Cascade That Regulates Stress Response
In vivo phosphorylation sites of the tobacco calcium-dependent protein kinases NtCDPK2 and NtCDPK3 were determined in response to biotic or abiotic stress. Stress-inducible phosphorylation was exclusively located in the variable N termini, where both kinases were phosphorylated differentially despit...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
January 29, 2010
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| In: |
The journal of biological chemistry
Year: 2010, Volume: 285, Issue: 13, Pages: 9740-9748 |
| ISSN: | 1083-351X |
| DOI: | 10.1074/jbc.M109.052126 |
| Online Access: | Verlag, kostenfrei, Volltext: http://dx.doi.org/10.1074/jbc.M109.052126 Verlag, kostenfrei, Volltext: http://www.jbc.org/content/285/13/9740 
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| Author Notes: | Claus-Peter Witte, Nana Keinath, Ullrich Dubiella, Raphael Demoulière, Anindita Seal, and Tina Romeis |
| Summary: | In vivo phosphorylation sites of the tobacco calcium-dependent protein kinases NtCDPK2 and NtCDPK3 were determined in response to biotic or abiotic stress. Stress-inducible phosphorylation was exclusively located in the variable N termini, where both kinases were phosphorylated differentially despite 91% overall sequence identity. In NtCDPK2, serine 40 and threonine 65 were phosphorylated within 2 min after stress. Whereas Thr65 is subjected to intra-molecular in vivo autophosphorylation, Ser40 represents a target for a regulatory upstream protein kinase, and correct NtCDPK2 membrane localization is required for Ser40 phosphorylation. NtCDPK3 is phosphorylated at least at two sites in the N terminus by upstream kinase(s) upon stress stimulus, first at Ser54, a site not present in NtCDPK2, and also at a second undetermined site not identical to Ser40. Domain swap experiments established that differential phosphorylation of both kinases is exclusively determined by the respective N termini. A cell death-inducing response was only observed upon expression of a truncated variant lacking the junction and calcium-binding domain of NtCDPK2 (VK2). This response required protein kinase activity and was reduced when subcellular membrane localization was disturbed by a mutation in the myristoylation and palmitoylation site. Our data indicate that CDPKs are integrated in stress-dependent protein kinase signaling cascades, and regulation of CDPK function in response to in vivo stimulation is dependent on its membrane localization. |
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| Item Description: | Gesehen am 29.06.2017 |
| Physical Description: | Online Resource |
| ISSN: | 1083-351X |
| DOI: | 10.1074/jbc.M109.052126 |