title: Transcriptome analysis of salt-stressed Deinococcus radiodurans and characterization of salt-sensitive mutants.
abstract: Deinococcus radiodurans is a bacterium best known for its extreme resistance to high levels of ionizing radiation. Gene expression profiles of D. radiodurans exposed to 0.3 M NaCl revealed that at least 389 genes were induced and 415 were repressed by twofold or more. A general down-regulation of the central metabolic pathways and a strong decrease of nrd gene expression, which encodes proteins necessary for DNA synthesis, likely reflect the growth retardation induced by NaCl stress. The expression of rsbRSTX, which encodes sigma B (σ(B)) activity regulators, was also reduced by NaCl stress even though D. radiodurans does not have σ(B). The mutation of rsbX (drB0027) decreased the tolerance of D. radiodurans to NaCl, suggesting the possible role of the Rsb module in NaCl response. On the other hand, NaCl stress activated genes associated with osmoprotectant accumulation: the pstSCAB operon, which encodes a high affinity phosphate transporter, and DRA0135 and DR1438, which are components of transporters of glycine betaine and trehalose. Survival analysis of mutant strains lacking DR0392 (membrane-binding protein) and DR1115 (S-layer protein), whose expressions were highly activated by NaCl, showed a reduction in NaCl tolerance. In addition, the Δdr0392 strain showed sensitivity to γ-irradiation compared to the wild type. These results suggest that DR0392 plays a role in the resistance of D. radiodurans to NaCl and γ-irradiation.
authors.affiliation: Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea; Interdisciplinary Program of Graduate School for Bioenergy & Biomaterials, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Seonghun
authors.initials: S
authors.lastname: Im
authors.forename: Minho
authors.initials: M
authors.lastname: Joe
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
authors.forename: Don-Hee
authors.initials: DH
authors.lastname: Park
authors.forename: Sangyong
authors.initials: S
authors.lastname: Lim
mesh_terms: D034301:Deinococcus / Q000187:drug effects* / Q000235:genetics*; D020869:Gene Expression Profiling; D050296:Microbial Viability / Q000187:drug effects; D009997:Osmotic Pressure; D012492:Salts / Q000633:toxicity*; D013312:Stress, Physiological
chemical_list: D012492:Salts
keywords: DR0392; Deinococcus radiodurans; NaCl stress; Transcriptome