Abstract
Upon exposure to low temperature, organisms perceive the change in temperature by certain mechanism(s) and regulate the expression of genes to acclimate to the new environment. In order to identify the low-temperature sensors from the cyanobacterium Synechocystis sp. PCC 6803, we inactivated each gene for 43 histidine kinases in the chromosome and found that in the mutant of histidine kinase 33, Hik33, the cold-inducibility of the desB gene for the ω3 acyl-lipid desaturase was clearly decreased. We also compared the gene expression in the cells of Hik33 mutant and cells of wild type after exposure to the low temperature by DNA microarray. The results indicated that Hik33 regulates the expression of some of the cold-inducible genes and cold-repressible genes. These results suggested that Synechocystis might have the second low-temperature sensor which regulates the expression of the genes which were not regulated by Hik33.
