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Current Genomics


ISSN (Print): 1389-2029
ISSN (Online): 1875-5488

A Survey of Chloroplast Protein Kinases and Phosphatases in Arabidopsis thaliana

Author(s): I. Schliebner, M. Pribil, J. Zuhlke, A. Dietzmann and D. Leister

Volume 9, Issue 3, 2008

Page: [184 - 190] Pages: 7

DOI: 10.2174/138920208784340740

Price: $65


Protein phosphorylation is a major mode of regulation of metabolism, gene expression and cell architecture. In chloroplasts, reversible phosphorylation of proteins is known to regulate a number of prominent processes, for instance photosynthesis, gene expression and starch metabolism. The complements of the involved chloroplast protein kinases (cpPKs) and phosphatases (cpPPs) are largely unknown, except 6 proteins (4 cpPKs and 2 cpPPs) which have been experimentally identified so far. We employed combinations of programs predicting N-terminal chloroplast transit peptides (cTPs) to identify 45 tentative cpPKs and 21 tentative cpPPs. However, test sets of 9 tentative cpPKs and 13 tentative cpPPs contain only 2 and 7 genuine cpPKs and cpPPs, respectively, based on experimental subcellular localization of their N-termini fused to the reporter protein RFP. Taken together, the set of enzymes known to be involved in the reversible phosphorylation of chloroplast proteins in A. thaliana comprises altogether now 6 cpPKs and 9 cpPPs, the function of which needs to be determined in future by functional genomics approaches. This includes the calcium-regulated PK CIPK13 which we found to be located in the chloroplast, indicating that calcium-dependent signal transduction pathways also operate in this organelle.

Keywords: Arabidopsis thaliana, chloroplast, chloroplast transit peptide, protein kinase, protein phosphatase, protein phosphorylation, proteomics

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