Ответ на стрессы у одноклеточной цианобактерии Synechocystis осуществляется при помощи нескольких регуляторных систем, например, двухкомпонентных, а также посредством отрицательной сверхспирализации геномной ДНК. В этой работе исследовано участие серин-треониновых протеинкиназ (СТПК) в реакции клеток цианобактерии Synechocystis на холодовой стресс. Скрининг коллекции мутантов по генам СТПК выявил группу из четырех протеинкиназ: SpkB, SpkD, SpkE, SpkG – как возможных регуляторов транскрипции при действии низкой температуры. Результаты исследования протеома бактерии Synechocystis, мутантной по SpkE, свидетельствуют о вкладе этой протеинкиназы в формирование белкового профиля. Реакция фосфорилирования in vitro рекомбинантного белка SpkE подтвердила, что это активная протеинкиназа с явным предпочтением основных белков в качестве субстратов.

Stress responses of the unicellular cyanobacterium Synechocystis involve several regulatory systems, including two-component ones, and negative supercoiling of genomic DNA. The role of serine/threonine protein kinases (STPKs) in the cold response was studied in Synechocystis. A screening of a collection of STPK mutants identified four enzymes-SpkB, SpkD, SpkE, and SpkG-as possible transcriptional regulators at lower temperatures. A proteome analysis in a SpkE Synechocystis mutant implicated SpkE in the formation of the protein pattern. In vitro phosphorylation assays of recombinant SpkE confirmed that the STPK was functionally active and utilized basic proteins as preferable substrates.

A homozygous insertion mutant with the inactivated clpP2gene, which encodes the proteolytic subunit of ATP-dependent peptidase, was obtained in the unicellular cyanobacterium Synechocystissp. PCC 6803. The mutant cannot grow under photoautotrophic conditions, but cells grown under heterotrophic conditions in a glucose-containing medium have active photosystems Iand II(PS Iand PS II). The loss of capacity for photoautotrophic growth is determined by a high sensitivity of mutant cells to the inactivating effect of light. Their incubation under light with an intensity above 10 μE m–2s–1inhibits cell growth in culture and causes degradation of photosynthetic pigments. It is proposed that the ClpP2 peptidase is involved in the protection of Synechocystis6803 cells from 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). The loss of capacity for photoautotrophic growth is determined by a high sensitivity of mutant cells to the inactivating effect of light. Their incubation under light with an intensity above 10 microE m-2 s-1 inhibits cell growth in culture and causes degradation of photosynthetic pigments. It is proposed that the ClpP2 peptidase is involved in the protection of Synechocystis 6803 cells from photoinhibition.