[Involvement of serine/threonine protein kinases in cold stress response in the cyanobacterium Synechocystis sp. PCC 6803: functional characterization of a protein kinase Spke].

Stress responses of the unicellular cyanobacterium Synechocystis are fulfilled via a number of regulatory systems, namely, two-component systems as well as through negative supercoiling of the genome DNA. We have studied an involvement of serine/threonine protein kinases (STPK) in the cyanobacterium Synechocystis cold stress response. A search for the STPK mutants allowed us to determine four protein kinases, SpkB, SpkD, SpkE and SpkG, which could regulate transcription under the low temperature.

Eukaryotic-like Ser/Thr protein kinases SpkC/F/K are involved in phosphorylation of GroES in the Cyanobacterium synechocystis.

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.

Serine/threonine protein kinase SpkA in Synechocystis sp. strain PCC 6803 is a regulator of expression of three putative pilA operons, formation of thick pili, and cell motility.

Previous studies showed that a Ser/Thr protein kinase, SpkA, in Synechocystis sp. strain PCC 6803 is involved in cell motility. The present study, in which DNA microarray analysis and electron microscopy were used, demonstrated that SpkA regulates the expression of putative pilA9-pilA10-pilA11-slr2018, pilA5-pilA6, and pilA1-pilA2 operons and is essential for the formation of thick pili.

The gene complement for proteolysis in the cyanobacterium Synechocystis sp. PCC 6803 and Arabidopsis thaliana chloroplasts.

A set of 62 genes that encode the entire peptidase complement of Synechocystis sp. PCC 6803 has been identified in the genome database of that cyanobacterium. Sequence comparisons with the Arabidopsis genome uncovered the presumably homologous chloroplast components inherited from their cyanobacterial ancestor.

[clpP2 gene encoding peptidase in cyanobacteria Synechocystis sp. PCC 6803 controls the sensitivity of cells to photoinhibition].

A homozygous insertion mutant with the inactivated clpP2 gene, which encodes the proteolytic subunit of ATP-dependent peptidase, was obtained in the unicellular cyanobacterium Synechocystis sp. PCC 6803. The mutant cannot grow under photoautotrophic conditions, but cells grown under heterotrophic conditions in a glucose-containing medium have active photosystems I and II (PS I and PS II).