Figure 4

Model of natural mechanisms of resistance against antibiotics targeting the transcriptional and/or the translational apparatus. The transcriptional and the translational apparatus are involved in protein synthesis (positive interactions PIa, PIb). The lethal effect of an antibiotic relies on its ability to inhibit transcription or translation (first negative interaction, NI1) including that of a gene encoding a protein neutralizing somehow the poisoning effect of the antibiotic (second negative interaction, NI2). The positive and the two negative interactions generate a positive circuit that leads to the establishment of a sigmoidal pattern of resistance to the antibiotic according to the level of expression of the gene responsible for the natural resistance mechanism.