Physiological and genetic responses of bacteria to osmotic stress
Vol. 53, No. 1
LASZLO N. CSONKA Department of Biological Sciences, Purddue University, West Lafayette, Indiana 47907
121 INTRODUCTION .................................................................................. THERMODYNAMIC BACKGROUND.................................................................................. 122 122 Osmotic Pressure .................................................................................. 122 Osmotic Potential .................................................................................. 123 Turgor Pressure .................................................................................. OSMOTIC PROPERTIESOF CELLS .................................................................................. 123 Relationship between Turgor Pressure and Cell Wall Expansion .................................................. 123 Effects of Hyper- or Hypoosmotic Shock on Bacteria ................................................................. 123 Measurement of Turgor Pressure of Bacteria........................................................................... 123 124 COMPATIBLE SOLUTES .................................................................................. 124 Osmoremedial Mutations .................................................................................. Mutations Conferring Sensitivity to Hyperosmotic Stress ............................................................ 124 125Compatible Solutes .................................................................................. 125 Potassium ions .................................................................................. 126 Glutamate and glutamine .................................................................................. Electrolyte balance of the cytoplasm.................................................................................. 126 127 -y-Aminobutyrate .................................................................................. 127 Trehalose .................................................................................. 127 .................................................................................. Osmoprotectants 127 Proline.................................................................................. 128 .................................................................................. Glycinebetaine 130 Choline .................................................................................. 130 Other osmoprotectants .................................................................................. OSMOREGULATION OF THE PERIPLASMIC SPACE.............................................................. 130 Membrane-Derived Oligosaccharides .................................................................................. 130 OSMOTIC CONTROL OF TRANSCRIPTION ........................................................................... 131 131 kdp ....................................................................................................... 132....................................................................................................... proU 132 Transcriptional regulation .................................................................................. 132 Structure of the proU operon .................................................................................. 132 Models for proU regulation.................................................................................. 134 proP .................................................................................. 134 ompF and ompC ................................................................................. Structure of the OmpF and OmpC proteins .......................................................................... 134 Positive-controlling OmpR and EnvZ...
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