Question

What are Cry proteins? Name an organism that produces it. How has man exploited this protein for his benefit?

Answer 1

The cry genes encode the Cry proteins, which are toxins or poisonous proteins. Cry proteins, also called insecticidal proteins.

Complete Answer:
- Cry proteins are a type of poisonous proteins which are secreted from the bacterial strains of Bacillus thuringiensis (B. thuringiensis). These proteins are found to be as crystal shaped when produced to form the bacteria, particularly during a specified growth phase.
- These toxins are coded a specific gene which is termed as Cry gene. Moreover, the gene which encodes the Cry proteins is called the Bt-toxin gene, as they are isolated from the B. thuringiensis bacteria.
- Man has exploited Cry proteins to build up some specific and potential transgenic crops such as Bt cotton, Bt corn, Bt brinjal and others, which shows resistance against the insects.
- The Cry proteins are contained in the B. thuringiensis bacteria in its inactive form.
- As soon as the inactive Cry proteins are taken by the insects, the inactivated Cry proteins get activated due to the alkaline pH of the insect gut. This leads to the lysis of the epithelial cells and finally the insect dies.

Note: The B. thuringiensis bacterium itself remains protected from the cry toxins due to the presence of methylated DNA. The Cry protein acts as an insecticide due to their properties towards the insects. The various potential transgenic crops such as Bt cotton, Bt corn, Bt brinjal and many others are mostly resistant to the insects of order Lepidoptera. The inclusion of these genes in various plants allows them to develop resistance against insects or pests and thus helps for superior yield and improved productivity.