The Influence of Polyamines on the Expression of Escherichia Coli Ribosome Hibernation Factor Raia

Abstract

RaiA is one of the main ribosome hibernation factors in Escherichia coli. Like other ribosome hibernation factors, this protein reversibly inhibits translation under stress conditions. According to published data, being induced by indole, RaiA is involved in bacterial persistence, which is considered to play important role in the recalcitrance of chronic infections to antibiotics. Previously, we showed that the raiA expression on the transcriptional level is stimulated by polyamines, in addition to indole. In this work, we investigated the influence of polyamines on the raiA expression on the translational level. We obtained the predicted secondary structures of raiA mRNA, the analysis of which showed the presence of the bulged-out region in the initiation site with a high probability. This may be a sign of gene involvement in the polyamine modulon. We constructed translational raiA::lacZ reporter fusion. Using this genetic construct, we studied the effects of polyamines on the raiA expression through an addition of putrescine, cadaverine or spermidine at concentrations of 1 mM and 2 mM. According to the results, the raiA expression is primarily stimulated by cadaverine at the stationary phase.