The selleck catalog phosphate group is transferred from the Hik to a conserved aspartate residue in Inhibitors,Modulators,Libraries the receiver domain of the cognate transducer, Rre. Upon phosphorylation, the Rre changes its conformation, and this change allows the binding of the Rre to the promoter regions of genes that are located further downstream in the acclimation pathway (Figure 1).In cyanobacteria, two-component systems, serine/threonine protein kinases (Spks), and sigma factors of RNA polymerase are conserved as potential candidates of sensors and transducers of environmental signals. Two-component systems have been found in prokaryotes (including cyanobacteria), fungi, yeasts, plants and lower Inhibitors,Modulators,Libraries animals [11], but not in higher animals. In eukaryotes and, in particular, in higher plants and higher animals, Spks or tyrosine protein kinases are the major sensors and/or transducers of environmental signals [12].

Sigma factors of RNA polymerases and regulatory factors that modify transcription Inhibitors,Modulators,Libraries are also involved in the regulation of gene expression. In addition, environmental stress can affect the superhelicity of DNA, which has been postulated to regulate gene expression [13,14].2.2. Two-component Regulatory Systems in Perception and Transduction of Environmental SignalsThe availability of the complete sequence Inhibitors,Modulators,Libraries of the Synechocystis genome [7] has allowed the construction of ��knockout�� libraries of specific sets of genes by targeted mutagenesis. This technique was used successfully for the identification of many potential sensors and transducers of environmental signals in Synechocystis [15�C17].

In addition, DNA microarray analysis of Dacomitinib the genome-wide expression of genes has allowed examination of the effects of mutations in specific genes for Hiks and Rres on the global expression of genes.The Synechocystis chromosome includes 44 putative genes for Hiks [7,18] and there are three genes for Hiks on its plasmids [8]. There are 42 putative genes for Rres on the chromosome and three on the plasmids. These 47 Hiks and 45 Rres are candidates for sensors and transducers of environmental signals. The major difficulty in association of genes for Hiks with their respective cognate Rres in Synechocystis is that they are scattered on its genome, and as a rule, are not organized into operons, as they are in E. coli or B. subtilis.

Thus, investigation of sensory Hiks and their cognate Rres requires mutations in individual Hik and Rre with subsequent examination of the stress-inducible expression of genes in the resultant mutants. In a series of experiments, 44 of the 47 hik genes and 42 of the 45 rre genes have been replaced with mutated genes (http://www.kazusa.or.jp/cyano/synechocystis/mutants/index.html). selleck screening library Several members of signal transduction pathway, which include hik2, hik11, hik26, rre23, rre25 and rre26 genes, were segregated incompletely.2.