title: Effects of environmental stresses on the activities of the uspA, grpE and rpoS promoters of Escherichia coli O157:H7.
abstract: Heat shock proteins and RNA polymerase sigma factor play an important role in protecting cells against environmental stresses, including starvation, osmotic and oxidative stresses, and cold shock. In this study, the effect of environmental stresses on activity of the auto-fluorescent Escherichia coli O157:H7 generated by the fusion of gfp(uv) to E. coli uspA, grpE and rpoS promoters were examined. Osmotic shock caused about a 4-fold increase in green fluorescence of E. coli O157:H7 harboring uspA::gfp(uv) or rpoS::gfp(uv) at 37 degrees C and room temperature whereas osmotic shock at 5 degrees C did not induce green fluorescence. When starved, E. coli O157:H7 possessing grpE::gfp(uv) was more sensitive for evaluating stress at low temperature while uspA::gfp(uv) was better suited for detecting the stress response at higher temperature. The uspA, grpE and rpoS promoters were up-regulated to varying degrees by stresses commonly encountered during food processing.
authors.affiliation: Department of Food Science and Canadian Research Institute for Food Safety, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Purushottam V
authors.initials: PV
authors.lastname: Gawande
authors.forename: Mansel W
authors.initials: MW
authors.lastname: Griffiths
mesh_terms: D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000378:metabolism; D019453:Escherichia coli O157 / Q000378:metabolism* / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005453:Fluorescence; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000378:metabolism*; D009994:Osmolar Concentration; D018384:Oxidative Stress; D012808:Sigma Factor / Q000378:metabolism; D013217:Starvation; D013696:Temperature; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C489400:GrpE protein, E coli; D006360:Heat-Shock Proteins; D012808:Sigma Factor; C446159:USP protein, E coli; C069567:sigma factor KatF protein, Bacteria