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ARS Home » Plains Area » Manhattan, Kansas » Center for Grain and Animal Health Research » Stored Product Insect and Engineering Research » Research » Publications at this Location » Publication #306907
Title: The role of proteolysis in the biological activity of Bt insecticidal crystal proteins

Author
item ZALUNIN, I - State Research Institute Of Genetics And Selection Of Industrial Microorganisms (GENETIKA)
item ELPIDINA, E - Moscow State University
item Oppert, Brenda

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 10/14/2014
Publication Date: 4/1/2015
Citation: Zalunin, I.A., Elpidina, E.N., Oppert, B.S. 2015. The role of proteolysis in the biological activity of Bt insecticidal crystal proteins. In: Soberon, M., Gao, Y., and Bravo, A., editors. Bt Resistance: Characterization and Strategies for GM Crops Producing Bacillus thuringiensis. Book Chapter. Oxfordshire, England: CABI Publishers. p. 107-118.

Interpretive Summary:

Technical Abstract: The crystal toxins (Cry) produced by the bacterium Bacillus thuringiensis have been successfully used in both spray formulations and transgenic crops to control some of the most problematic insect pests. The delta-endotoxins of B. thuringiensis are functionally-active in the insect gut and interact with and are processed by proteolytic enzymes. The structure of Cry proteins has specific features that not only permit them to retain their biological activity in the hostile environment of the insect gut, but also to use the process of proteolysis in the solubilization and activation of Cry protoxins. B. thuringiensis Cry proteins are found in parasporal inclusions in the bacterium, and they are grouped by amino acid sequence identity, with over 70 Cry toxins described thus far (Crickmore et al., 2014). Many Cry proteins belong to a group of toxins referred to as 3d-Cry toxins (Pardo-López et al., 2013). The term “3d” refers to the three domains connected by extended loops that are found in all 3d-Cry proteins. Within the 3d-Cry toxins, there are 130-145 kDa Cry protoxins that contain an extended C-terminus that is hydrolyzed by gut proteases, and 65-73 kDa Cry protoxins, which lack an extended C-terminus (and therefore do not require this processing for activity); all 3d-Cry proteins are hydrolyzed at the N-terminus by gut proteases to produce an active toxin. Therefore, proteases are essential to the functionality of Cry insecticidal toxins, and thus significant research efforts have been made to understand the integral role of proteases in Cry toxicity.