title: Eukaryotic-like Ser/Thr protein kinases SpkC/F/K are involved in phosphorylation of GroES in the Cyanobacterium synechocystis.
abstract: Serine/threonine protein kinases (STPKs) are the major participants in intracellular signal transduction in eukaryotes, such as yeasts, fungi, plants, and animals. Genome sequences indicate that these kinases are also present in prokaryotes, such as cyanobacteria. However, their roles in signal transduction in prokaryotes remain poorly understood. We have attempted to identify the roles of STPKs in response to heat stress in the prokaryotic cyanobacterium Synechocystis sp. PCC 6803, which has 12 genes for STPKs. Each gene was individually inactivated to generate a gene-knockout library of STPKs. We applied in vitro Ser/Thr protein phosphorylation and phosphoproteomics and identified the methionyl-tRNA synthetase, large subunit of RuBisCO, 6-phosphogluconate dehydrogenase, translation elongation factor Tu, heat-shock protein GrpE, and small chaperonin GroES as the putative targets for Ser/Thr phosphorylation. The expressed and purified GroES was used as an external substrate to screen the protein extracts of the individual mutants for their Ser/Thr kinase activities. The mutants that lack one of the three protein kinases, SpkC, SpkF, and SpkK, were unable to phosphorylate GroES in vitro, suggesting possible interactions between them towards their substrate. Complementation of the mutated SpkC, SpkF, and SpkK leads to the restoration of the ability of cells to phosphorylate the GroES. This suggests that these three STPKs are organized in a sequential order or a cascade and they work one after another to finally phosphorylate the GroES.
authors.affiliation: Institute of Plant Physiology, Botanicheskaya Street 35, 127276 Moscow, Russia.
authors.forename: Anna
authors.initials: A
authors.lastname: Zorina
authors.forename: Natalia
authors.initials: N
authors.lastname: Stepanchenko
authors.forename: Galina V
authors.initials: GV
authors.lastname: Novikova
authors.forename: Maria
authors.initials: M
authors.lastname: Sinetova
authors.forename: Vladimir B
authors.initials: VB
authors.lastname: Panichkin
authors.forename: Igor E
authors.initials: IE
authors.lastname: Moshkov
authors.forename: Vladislav V
authors.initials: VV
authors.lastname: Zinchenko
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Shestakov
authors.forename: Iwane
authors.initials: I
authors.lastname: Suzuki
authors.forename: Norio
authors.initials: N
authors.lastname: Murata
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Los
mesh_terms: D018835:Chaperonin 10 / Q000378:metabolism*; D000458:Cyanobacteria / Q000201:enzymology*; D005810:Multigene Family; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D018835:Chaperonin 10; D017346:Protein Serine-Threonine Kinases