RECOVERY OF RESPIRATION FOLLOWING THE SOS RESPONSE OF ESCHERICHIA-COLI REQUIRES RECA-MEDIATED INDUCTION OF 2-KETO-4-HYDROXYGLUTARATE ALDOLASE

Agents that damage DNA in Escherichia coli or interfere with its repli cation induce DNA repair and mutagenesis via the SOS response, This we ll-known activity is regulated by the RecA protein and the LexA repres sor, Following repair or bypass of the DNA lesion, the cell returns to its resting state by a largely unknown process. We found that 2-keto- 3-hydroxyglutarate aldolase (4-hydroxy-2-oxoglutarate aldolase; EC 4.1 .3.16) is necessary for the recovery of respiration and that it is reg ulated by the SOS response, This protein was induced by DNA-damaging a gents, Induction required RecA activation, When the LexA regulon was r epressed, activation of RecA was not sufficient for induction, indicat ing the requirement for an additional protein under LexA control, Fina lly, a mutant in the corresponding hga gene was UV sensitive, 2-Keto-4 -hydroxyglutarate aldolase also plays a role in respiratory metabolic pathways, which suggests a mechanism for respiration resumption during the termination of the SOS response.