Biochemical characterization of Shewanella-like protein phosphatase 1 in Arabidopsis thaliana

Date
2018-01-09
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Abstract
The Arabidopsis thaliana genome encodes two isoforms of Shewanella-like phosphatases - SLP1, which is localized in chloroplasts of photosynthetic tissues, and SLP2, a protein localized in mitochondria consistent with its origin in bacteria. Due to its unique pattern of chloroplast localization, characterization of SLP1 was undertaken to identify its substrates and establish its biological function. In the presented work, one of the largest quantitative phosphoproteomic studies on A. thaliana was conducted to identify SLP1's potential substrates by comparing WT and slp1 KO phosphoproteomic profiles. This led to identification of 170 high-confidence substrates, all residing in chloroplast and may be directly involved in SLP1 signaling network, including starch synthesis regulation and protein import into chloroplasts. A close examination of phospho-peptides from the identified substrates revealed a unique acidic motif surrounding the SLP1 (de)phosphorylation sites, resembling the chloroplastic casein kinase II (cpCKII) phosphorylation sites.
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Keywords
Bacterial-like phosphatase, Arabidopsis thaliana, SLP1, AtSLP1, Phosphorylation, Quantitative phosphoproteomics, Plant biochemistry, Shewanella-like, Starch metabolism regulation, SS1, Starch syntahse 1, Protein import phosphorylation regulation
Citation
Vahab, A.R. (2018). Biochemical characterization of Shewanella-like protein phosphatase 1 in Arabidopsis thaliana. University of Calgary, Calgary, AB