title: Identification of four plastid-localized protein kinases.
abstract: In chloroplasts, protein phosphorylation regulates important processes, including metabolism, photosynthesis, gene expression, and signaling. Because the hitherto known plastid protein kinases represent only a fraction of existing kinases, we aimed at the identification of novel plastid-localized protein kinases that potentially phosphorylate enzymes of the tetrapyrrole biosynthesis (TBS) pathway. We screened publicly available databases for proteins annotated as putative protein kinase family proteins with predicted chloroplast localization. Additionally, we analyzed chloroplast fractions which were separated by sucrose density gradient centrifugation by mass spectrometry. We identified four new candidates for protein kinases, which were confirmed to be plastid localized by expression of GFP-fusion proteins in tobacco leaves. A phosphorylation assay with the purified kinases confirmed the protein kinase activity for two of them.
authors.affiliation: Humboldt Universität zu Berlin, Institute of Biology/Plant Physiology, Berlin, Germany.
authors.forename: Andreas S
authors.initials: AS
authors.lastname: Richter
authors.affiliation: Humboldt Universität zu Berlin, Institute of Biology/Plant Physiology, Berlin, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Gartmann
authors.affiliation: Humboldt Universität zu Berlin, Institute of Biology/Plant Physiology, Berlin, Germany.
authors.forename: Mona
authors.initials: M
authors.lastname: Fechler
authors.affiliation: Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Rödiger
authors.affiliation: Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany.
authors.forename: Sacha
authors.initials: S
authors.lastname: Baginsky
authors.affiliation: Humboldt Universität zu Berlin, Institute of Biology/Plant Physiology, Berlin, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Grimm
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics
chemical_list: D060365:Chloroplast Proteins; D011494:Protein Kinases
keywords: chloroplast; post-translational control; protein kinase