THE FATS OF ESCHERICHIA-COLI DURING INFANCY AND OLD-AGE - REGULATION BY GLOBAL REGULATORS, ALARMONES AND LIPID INTERMEDIATES

The fluidity and phase state of bacterial lipid bilayers commonly chan ge in response to ambient environmental conditions to maintain the cri tical functions of the envelope as a semipermeable and selective bound ary. A special, and intricate, set of alterations in membrane lipid me tabolism is elicited by conditions causing growth arrest. Under such c onditions, specific alterations in the membrane lipid-fatty acid compo sition are required for survival of the cell and, concurrently, the me mbrane lipids are suggested to serve as endogenous reserves providing carbon/energy for maintenance requirements. It appears that the global regulator FadR is required for both of these activities to be perform ed properly and that the FadR regulon is interconnected to the univers al stress response of Escherichia coli, FadR, in conjuction with long- chain fatty acyl-CoA, long-chain acyl-ACP, ppGpp and cAMP, are key pla yers in regulating the activities of enzymes and expression of genes i nvolved in fatty acid and phospholipid metabolism in dividing and agei ng E. coli cells.