Resumen de Cell Wall Stress-sensing Regulatory Systems in Gram Negative Bacteria
Juan A. Ayala, Felipe Cava, Miguel A. de Pedro
The cell envelope is the major line of defence against environmental threats. It is an essential but vulnerable structure that shapes the cell and counteracts the turgor pressure. It provides a sensory interface, a molecular sieve and a structural support, mediating information flow, transport and assembly of supramolecular structures. Therefore, maintenance of cell envelope integrity in the presence of deleterious conditions is crucial for survival. Several envelope stress responses, including two components regulatory systems (TCRS), of Escherichia coli are involved in the maintenance, adaptation and protection of the bacterial cell wall in response to a variety of stresses. Recent studies indicate that these stress responses exist in many Gram negative pathogens. Particular emphasis has been made on the identified TCRS and their activating signals. Another aspect of stress response is the generation of morphological modifications. Most bacteria alter shape when growth conditions change and upon symbiotic or parasitic processes. Any modification in cell shape is connected with cell wall metabolism and requires specific regulatory mechanisms. Recent advances support the existence of complex mechanisms mediating morphological responses to stress involving inter and intra-specific signalling.
