In fact, the response to a certain stress is often accompanied by seemingly unrelated responses. For example, glucose- or nitrogen-starved cultures of Escherichia coli exhibit enhanced resistance to heat, H2O2, or osmotic challenge (Jenkins et al., 1988; Jenkins et al., 1990); furthermore, when bacteria are challenged with high osmolarity, they acquire increased resistance to high temperature and oxidative stresses (Tesone et al., 1981; Hengge-Aronis et al., 1993; Canovas et al., 2001; Gunasekera et al., 2008). Elucidation of bacterial stress responses
will facilitate understanding of bacterial physiology. The stationary phase-dependent regulatory protein (SdrP) is a CRP/FNR family transcriptional regulator from Thermus thermophilus Selleckchem PI3K inhibitor HB8 (Agari et al., 2008), which is an extremely thermophilic bacterium isolated from the water at a Japanese hot spring. Thermus thermophilus HB8 can grow at 47–85 °C, and its optimum
temperature range is from 65 to 72 °C (Oshima & Imahori, 1974). Previously, we demonstrated that sdrP mRNA increases upon entry into the stationary phase, and SdrP positively regulates the expression of several kinds of genes, which are possibly involved in nutrient and energy supply, redox control, and polyadenylation of mRNA (Agari et al., 2008). Transcriptional activation occurs independently of any added effector GDC-0980 molecule, which is supported by the observation that the three-dimensional structure of apo-SdrP is similar to that of almost the DNA-binding form of E. coli CRP (Agari et al., 2008). In this study, to gain further insight into the cellular function of SdrP, we developed a new approach to identify novel genes whose expression was regulated by SdrP. The T. thermophilus wild-type and csoR gene-deficient (ΔcsoR) strains (Sakamoto et al., 2010) were cultured at 70 °C in a rich or synthetic medium (Supporting Information, Table S1). The details of the culture conditions
are given in the NCBI Gene Expression Omnibus (GEO) database (http://www.ncbi.nlm.nih.gov/projects/geo/), the accession numbers being GSE21433 [for N,N,N′,N′-tetramethylazodicarboxamide (diamide) treatment], GSE21430 (for H2O2 treatment), GSE20900 (for ZnSO4 treatment), GSE21432 (for tetracycline treatment), GSE21289 (for NaCl treatment), GSE21435 (for ethanol treatment), GSE19508 (for CuSO4 treatment of the wild-type strain), and GSE19509 (for CuSO4 treatment of the ΔcsoR strain). Total RNA was isolated from each strain, as described previously (Shinkai et al., 2007). Using the RNA (1 μg) as a template, RT-PCR was performed in 20 μL reaction mixtures with a PrimeScript RT-PCR kit (Takara Bio. Inc.) according to the manufacturer’s instructions. The reverse transcription reaction was performed at 42 °C for 20 min. Using 1 μL of the reaction mixture as a template, PCR was performed in the presence of 0.