title: Differentially expressed genes after hyper- and hypo-salt stress in the halophilic archaeon Methanohalophilus portucalensis.
abstract: Methanohalophilus portucalensis FDF1 can grow over a range of external NaCl concentrations, from 1.2 to 2.9 mol/L. Differential gene expression in response to long-term hyper-salt stress (3.1 mol/L of NaCl) and hypo-salt stress (0.9 mol/L of NaCl) were compared by differential display RT-PCR. Fourteen differentially expressed genes responding to long-term hyper- or hypo-salt stress were detected, cloned, and sequenced. Several of the differentially expressed genes were related to the unique energy-acquiring methanogenesis pathway in this organism, including the transmembrane protein MttP, cobalamin biosynthesis protein, methenyl-H4MPT cyclohydrolase and monomethylamine methyltransferase. One signal transduction histidine kinase was identified from the hyper-salt stress cultures. Moreover, 3 known stress-response gene homologues - the DNA mismatch repair protein, MutS, the universal stress protein, UspA, and a member of the protein-disaggregating multichaperone system, ClpB - were also detected. The transcriptional analysis of these long-term salt stress response and adaptation-related genes for cells immediately after salt stress indicated that the expression of the energy metabolism genes was arrested during hyper-salt shock, while the chaperone clpB gene was stimulated by both hypo- and hyper-salt shock.
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, ROC.
authors.forename: Chao-Jen
authors.initials: CJ
authors.lastname: Shih
authors.forename: Mei-Chin
authors.initials: MC
authors.lastname: Lai
mesh_terms: D000222:Adaptation, Physiological; D001483:Base Sequence; D004734:Energy Metabolism; D020869:Gene Expression Profiling; D019848:Gene Expression Regulation, Archaeal; D017019:Methanosarcinaceae / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: D012965:Sodium Chloride