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Universal Molecular Triggers of Stress Responses in Cyanobacterium Synechocystis

1
Department of Molecular Biosystems, K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya street 35, 127276 Moscow, Russian
2
Department of Biology, School of Natural Sciences, Kean University, 1000 Morris Ave, Union, NJ 07083, USA
*
Author to whom correspondence should be addressed.
Received: 5 July 2019 / Revised: 15 August 2019 / Accepted: 17 August 2019 / Published: 20 August 2019
(This article belongs to the Section Life Sciences)
Systemic analysis of stress-induced transcription in the cyanobacterium Synechocystis sp. strain PCC 6803 identifies a number of genes as being induced in response to most abiotic stressors (heat, osmotic, saline, acid stress, strong light, and ultraviolet radiation). Genes for heat-shock proteins (HSPs) are activated by all these stresses and form a group that universally responds to all environmental changes. The functions of universal triggers of stress responses in cyanobacteria can be performed by reactive oxygen species (ROS), in particular H2O2, as well as changes in the redox potential of the components of the photosynthetic electron transport chain. The double mutant of Synechocystis sp. PCC 6803 (katG/tpx, or sll1987/sll0755), which is defective in antioxidant enzymes catalase (KatG) and thioredoxin peroxidase (Tpx), cannot grow in the presence of exogenous hydrogen peroxide (H2O2); and it is extremely sensitive to low concentrations of H2O2, especially under conditions of cold stress. Experiments on this mutant demonstrate that H2O2 is involved in regulation of gene expression that responds to a decrease in ambient temperature, and affects both the perception and the signal transduction of cold stress. In addition, they suggest that formation of ROS largely depends on the physical state of the membranes such as fluidity or viscosity. In cyanobacteria, an increase in membrane turnover leads to a decrease in the formation of ROS and an increase in resistance to cold stress. Therefore: (1) H2O2 is the universal trigger of stress responses in cyanobacterial cells; (2) ROS formation (in particular, H2O2) depends on the physical properties of both cytoplasmic and thylakoid membranes; (3) The destructive effect of H2O2 is reduced by increasing of fluidity of biological membranes. View Full-Text
Keywords: cyanobacteria; membrane fluidity; ROS; stress responses; universal triggers cyanobacteria; membrane fluidity; ROS; stress responses; universal triggers
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Mironov, K.S.; Sinetova, M.A.; Shumskaya, M.; Los, D.A. Universal Molecular Triggers of Stress Responses in Cyanobacterium Synechocystis. Life 2019, 9, 67.

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