Figure 7.

Model showing the effect of ciprofloxacin on parasites. In the absence of apicoplast targeted drug like ciprofloxacin, nuclear encoded apicoplast targeted (NEAT) genes are transcribed in the nucleus (N) and transported into the cytoplasm (C) where they are translated as unprocessed protein that are translocated to the apicoplast (A) and gets processed. During second life cycle following drug treatment, the apicoplast achieve critical concentration of the drug that affects apicoplast function and morphology that inhibits translocation of NEAT proteins into the apicoplast which in turn may down-regulate the translation of these proteins. Therefore, a dual mechanism of inhibition of translocation of NEAT proteins and modulation of translation level of these proteins may contribute to the delayed death effect exerted by such drugs like ciprofloxacin. The solid and broken circles in apicoplast indicate the apicoplast genome in the absence and presence of drug.