Involvement of ppGpp, ribosome modulation factor, and stationary phase-specific sigma factor sigma(S) in the decrease in cell viability caused by spermidine

Accumulation of spermidine in Escherichia coli causes a decrease in cell vi ability at the late stationary phase of cell growth. The mechanism underlyi ng this effect has been studied. Spermidine accumulation caused an increase in the level of ppGpp and a decrease in ribosome modulation factor (RMF) a nd stationary phase-specific sigma factor sigma(S), both of which are belie ved to be involved in cell viability. Transformation of E. coli with the ge ne for stringent factor, which synthesizes ppGpp, also caused a significant decrease in the levels of RMF and sigma(S) factor and a decrease in cell v iability. The results strongly suggest that the accumulation of ppGpp is al so involved in the decrease in cell viability and that the sigma(S) factor assists the function of RMF in cell viability. (C) 1999 Academic Press.