Conversion of potentially lethal damage to lethal damage in Escherichia coli inhibited by caffeine

If E. coli cells with potentially lethal damage to their DNA are starved of amino acids they rapidly lose viability (Kuokalova and Kuhrova 1980). This phenomenon is called secondary lethality (SL). In the course of secondary lethality there is a decrease in the molecular weight of DNA to a value on average three times lower (DNA fragmentation), and part of the DNA is reduced to acid-soluble fractions (DNA degradation). Caffeine inhibits SL, and both these processes of DNA decay. The lowest effective concentration is 5 mg/ml, with maximum effect at a concentration of 10 mg/ml. SL is also inhibited by the absence of an energy source. The possible mechanism of SL is discussed on the basis of these results. (author)