Sensors and Signal Transducers of Environmental Stress in Cyanobacteria

Abstract

The perception of environmental stress and the subsequent transduction of stress signals are primary events in the acclimation of all organisms to changes in their environment. Many of the 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. Almost all of the histidine kinases (Hiks) and response regulators (Rres) 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 the Hiks and Rres that perceive and transduce signals of environmental stress. In this chapter, we summarize recent progress in the identification of regulatory two-component systems. In addition, we discuss the potential roles of Spks, DNA supercoiling, sigma factors and transcription factors in the regulation of the responses of cyanobacterial cells to various types of stress.