Abstract
In many organisms, genes for heat shock proteins are upregulated under sudden increase in temperature and this is essential for accliamtion to heat shock conditions. We analyzed profiles of the gene expression under heat shock conditions in the cyanobacterium Synechocystis sp. PCC 6803 with DNA microarray. As expected, the expression of a number of genes for the known heat shock proteins were enhanced by heat shock. Moreover, a gene encoding a putative histidine kinase (Hik) was also upregulated. Inactivation of the gene for the heat-inducible Hik enhanced levels of expression of the groESL operon even at normal growth temperature, such as 34 degree C, and acquired tolerance against heat shock. These results indicated that the heat-inducible Hik might have repressed the expression of heat shock genes under normal growth conditions and might be involved in the regulation of gene expression under heat shock conditions.
