Stress Sensors and Signal Transducers in Cyanobacteria

Abstract

In living cells, the perception of environmental stress and the subsequent transduction of stress signals are primary events in the acclimation to changes in the environment. Some molecular sensors and transducers of environmental stress cannot be identified by traditional and conventional methods. Based on genomic information, a systematic approach has been applied to the solution of this problem in cyanobacteria, involving mutagenesis of potential sensors and signal transducers in combination with DNA microarray analyses for the genome-wide expression of genes. Forty-five genes for the histidine kinases (Hiks), 12 genes for serine-threonine protein kinases (Spks), 42 genes for response regulators (Rres), seven genes for RNA polymerase sigma factors, and nearly 70 genes for transcription factors have been successfully inactivated by targeted mutagenesis in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Screening of mutant libraries by genome-wide DNA microarray analysis under various stress and non-stress conditions has allowed identification of proteins that perceive and transduce signals of environmental stress. Here we summarize recent progress in the identification of sensory and regulatory systems, including Hiks, Rres, Spks, sigma factors, transcription factors, and the role of genomic DNA supercoiling in the regulation of the responses of cyanobacterial cells to various types of stress.

Integrated analysis of engineered carbon limitation in a quadruple CO2/HCO3--uptake mutant of Synechocystis sp. PCC 6803

“…Moreover, transcripts of the alternative sigma factors sigB (sll0306), sigD (sll2012), and sigH (sll0856) were highly induced in D4, irrespective of Ci supply. These transcripts responded to general stress (Los et al, 2010), high-light and redox stress (Imamura et al, 2003), oxidative stress (Li et al, 2004), or heat stress (Huckauf et al, 2000;Tuominen et al, 2003;Singh et al, 2006). Additionally, the expression of slr1738, coding for a peroxide responsive regulator (PerR)/ferric uptake regulation protein (FUR)-type transcriptional regulator of oxidative stress (Li et al, 2004; Garcin et al, Table I.…”

Reactive oxygen species are involved in the morphology-determining mechanism of Fremyella diplosiphon cells during complementary chromatic adaptation

“…Their genome has evolved in such a way that they can sense and respond to different environmental stimuli (Los et al, 2010). Due to their photoautotrophic nature, they have also developed an ability to fine-tune their photosynthetic machinery in response to ambient light quality.…”

“…The present study demonstrates that ROS levels are correlated with morphological changes during CCA in F. diplosiphon; however, how this signal is translated into morphological changes by regulating cytoskeletal proteins or components of the cytoskeleton to give final morphological changes is still unknown. Notably, cyanobacterial genomes possess several sensor kinases to sense oxidative stress (Los et al, 2010) and it will be interesting to determine whether morphological changes in F. diplosiphon during CCA involve a sensor kinase of oxidative stress that directly affects the integrity of the cytoskeletal proteins to give the spherical morphology under RL.…”

Proteomic analysis of post translational modifications in cyanobacteria

“…The two-component signal transduction systems, consisting of histidine kinases and the corresponding response regulators, was previously considered as the predominant phosphorylation based signal transduction mechanism in cyanobacteria [62]. However, recently, comprehensive functional analyses have revealed that Ser/Thr/Tyr kinases and phosphatases play vital roles in regulating many critical processes in cyanobacteria, such as stress adaptation, cell differentiation, cell motility, carbon and nitrogen metabolism and photosynthesis [63].…”