Escherichia coliCryptic Prophages Sense Nutrients to Control Persister Cell Resuscitation

Abstract

We determined previously that some cryptic prophages are not genomic junk but instead enable cells to combat myriad stresses as part of an active stress response. However, how these phage fossils affect the extreme stress response of dormancy; i.e., how cryptic prophages affect persister cell formation and resuscitation, has not been fully explored. Persister cells form as a result of stresses such as starvation, antibiotics, and oxidative conditions, and resuscitation of these persister cells likely causes recurring infections such as those associated with tuberculosis, cystic fibrosis, and Lyme disease. Unlike for the active stress response, here we find that deletion of each of the nine Escherichia coli cryptic prophages has no effect on persister cell formation. Strikingly, elimination of each cryptic prophage results in an increase in persister cell resuscitation with a dramatic increase in resuscitation upon deleting all nine prophages. This increased resuscitation includes eliminating the need for a carbon source and is due to activation of the phosphate import system as a result of inactivating transcriptional regulator AlpA of the CP4-57 cryptic prophage, since we found alpA increases persister resuscitation, and AlpA represses phosphate regulator PhoR. Therefore, we report a novel cellular stress mechanism controlled by cryptic prophages: regulation of phosphate uptake which controls the exit of the cell from dormancy and prevents premature resuscitation in the absence of nutrients.