Question 7: Many proteins are secreted in their inactive form. This is also true of many toxic proteins produced by micro organisms. Explain how the mechanism is useful for the organism producing the toxin?
Answer:
Development of insecticidal resistance is the application of transgenic plants. By the Recombinant DNA technology, it is possible to develop crops which are intrinsically resistant to insects. When the toxins are present in inactive form, the organisms which produces these toxins, does not harm anymore. This mechanism is useful for micro-organisms because they become active by certain metabolic and biochemical changes like pH or temperature. For example: in Bt (Bacillus thuringiensis) toxin, insecticidal proteins called cry proteins, when get accumulated in the bacterium as an inactive state and after ingestion by the insect, in alkaline pH of gut, this protoxin cleaved by protease, results in the shorter version of proteins and shows toxicity/ acidity, by binding inside of the insect’s gut and damages the surface epithelium. Thus, these toxins resist the proteins and by the action of host, these micro- organisms does not get killed.
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