title: [Two-dimensional gel electrophoresis analysis of moderately halophilic bacterium Halobacillus dabanensis D-8T under hypoosmotic shock condition].
abstract: Halobacillus dabanensis D-8T was isolated from the saline deposits of Daban lake in Xinjiang of China, and is able to grow in complex medium containing 0.5% to 25% salt. To figure out the survival mechanisms of Gram-positive moderately halophilic bacteria under hypoosmotic shock conditions, two-dimensional gel electrophoresis (2-DE) was carried out to investigate differential protein expression profiles of H. dabanensis D-8T in response to low osmotic challenge. The 2-D gels were stored as dry gels and their images were taken by ImageScanner and analyzed by Imagemaster 2D Platinum software. About 650 protein spots were detected in 2-D gel. Most of proteins were distributed in molecular mass of 17.5 - 66kDa and the range of isoelectric point 4.0 - 5.9. A total of 34 protein spots were found to alter their expression after strain D-8T was subjected to hypoosmotic shock from 20% to 0% salinity for 5 min and 50 min. Among them, the expression of 20 protein spots is up-regulated including 6 new protein spots, while that of 14 protein spots is down-regulated in answer to sudden osmotic down-shift. Protein spots of interest were excised from the gels and digested by trypsin. By means of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) and MASCOT search engine, 4 up-regulated protein spots were identified with peptide mass fingerprint, and are similar to heat shock protein DanK, rod shape-determining protein, penicillin-binding protein (PBP-1A) and 5-enolpyruvoylshikimate-3-phosphate synthase, respectively. Noticeably, PBP-1A firstly was up-regulated after shock of 5 min but disappeared after shock of 50 min. This indicated that the strain activate a minor mechanism of peptidoglycan synthesis to compensate the major synthesis mechanism for cells survival through a down-shift challenge. In addition, this paper was the first report that heat shock proteins were up-regulated in response to sudden osmotic down-shift.
authors.affiliation: Key Laboratory of Agro-Microbial Resources and Application of Agricultural Ministry, College of Biological Sciences, China Agricultural University, Beijing 100094, China. fengdq@sun.im.ac.cn
authors.forename: De-Qin
authors.initials: DQ
authors.lastname: Feng
authors.forename: Li-Shi
authors.initials: LS
authors.lastname: Xie
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Li
authors.forename: Su-Sheng
authors.initials: SS
authors.lastname: Yang
mesh_terms: D001406:Bacillaceae / Q000737:chemistry*; D001426:Bacterial Proteins / Q000032:analysis*; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods*; D009997:Osmotic Pressure; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001426:Bacterial Proteins