Figure 5.

The hyperthetical resistance mechanism involved in the development of QdNOs resistance. The decrease in the expression of the outer membrane porin gene ompD leads to the loss of OmpD protein, which reduces the intake of olaquindox. The up-regulation of multidrug resistance efflux pump gene acrB increases olaquindox efflux. The PTS systerm initiate a metabolic feedback dependent on tricarboxylic acid (TCA) cycle, stimulate the oxidation of NADH through the electron transport chain, promote superoxide formation, damage the structure of Fe-S clusters, lead to the formation of hydroxyl radicals and finally damage DNA; The Changes in the expression of genes umuC, rusA, and rutG trigger DNA repair; Changes in the expression of genes such as iraD, cdtA, vgrG, and ydeE cause gene mutations and affect DNA replication.