The role of the natural polyamine putrescine in defense against oxidative stress in Escherichia coli

Putrescine up-regulated, in a concentration-dependent manner, the expressio n levels of the oxyR and katG genes of Escherichia coli cells exposed to hy drogen peroxide. Its stimulatory effect was more pronounced under condition s of strong oxidative stress. 1,4-Diamino-2-butanone, a specific inhibitor of putrescine synthesis, also inhibited oxyR expression under oxidative str ess. When added to inhibited cells, putrescine relieved this inhibitory eff ect. Addition of putrescine to E. coli cultures exposed to oxidative stress led to increased cell survival.