Differential expression of membrane proteins helps Antarctic Pseudomonas syringae to acclimatize upon temperature variations.

Antarctic bacteria are adapted to the extremely low temperature. The transcriptional and translational machineries of these bacteria are adapted to the sub-zero degrees of temperature. Studies directed towards identifying the changes in the protein profiles during changes in the growth temperatures of an Antarctic bacterium Pseudomonas syringae Lz4W may help in understanding the molecular basis of cold adaptation. In this study, subcellular fractionation methods of proteins were used for the enrichment and identification of proteins including low abundance proteins. The membrane proteins of the bacterium P. syringae Lz4W were prepared employing sucrose density gradient method. The proteins were separated through 2D gel-electrophoresis with the pH ranges 3-10, 4-7 and 5-8 using the detergent, amidosulfobetaine (ASB-14). The proteins separated on the 1D SDS PAGE and 2D gels were identified with the help of LC-ESI MS/MS and MALDI TOF TOF using bioinformatic programs MASCOT and SEQUEST. Since the genome sequence of P. syringae Lz4W is not available, the proteins are identified by using the genome database of the Pseudomonas sp. available at NCBI. The present studies focus on identifying temperature dependent expression of proteins by employing LC-MS/MS method and the functional significance of these proteins is discussed.