Mechanisms of Resistance to Silver Nanoparticles in Endodontic Bacteria: A Literature Review

Figure 2

Appearance of a persistence phenotype. (1) Activation of RelA (by starvation and several stimuli) promotes the accumulation of ppGpp. (2) The ppGppppGpp inhibits the exopolyphosphatase (PPX), the enzyme that degrades polyP, promoting the accumulation of polyP. (3) PolyP causes the degradation of antitoxins. (4) Free and activated toxins induce persistence. (5) The accumulation of ppGpp interferes with mRNAs and induces the appearance of a persistence phenotype. (6) Finally, ppGpp also stimulates the accumulation of RpoS, a master regulator of the general stress response.