Regode, V and Kuruba, S and Mohammad, A S and Sharma, H C (2016) Isolation and Characterization of Gut Bacterial Proteases Involved in Inducing Pathogenicity of Bacillus thuringiensis Toxin in Cotton Bollworm, Helicoverpa armigera. Frontiers in Microbiology, 7 (1567). 01-11. ISSN 1664-302X
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Abstract
Bacillus thuringiensis toxin proteins are deployed in transgenic plants for pest management. The present studies were aimed at characterization of gut bacterial proteases involved in activation of inactive Cry1Ac protoxin (pro-Cry1Ac) to active toxin in Helicoverpa armigera. Bacterial strains were isolated from H. armigera midgut andscreened for their proteolytic activation toward pro-Cry1Ac. Among 12 gut bacterial isolates seven isolates showed proteolytic activity, and proteases from three isolates (IVS1, IVS2, and IVS3) were found to be involved in the proteolytic conversion of pro-Cry1Ac into active toxin. The proteases from IVS1, IVS2, and IVS3 isolates were purified to 11.90-, 15.50-, and 17.20-fold, respectively. The optimum pH and temperature for gut bacterial protease activity was 8.0 and 40°C. Maximum inhibition of total proteolytic activity was exerted by phenylmethane sulfonyl fluoride followed by EDTA. Fluorescence zymography revealed that proteases from IVS1, IVS2, and IVS3 were chymotrypsin-like and showing protease band at ~15, 65, and 15 kDa, respectively. Active Cry1Ac formed from processing pro-Cry1Ac by gut bacterial proteases exhibited toxicity toward H. armigera. The gut bacterial isolates IVS1, IVS2, and IVS3 showed homology with B. thuringiensis (CP003763.1), Vibrio fischeri (CP000020.2), and Escherichia coli (CP011342.1), respectively. Proteases produced by midgut bacteria are involved in proteolytic processing of B. thuringiensis protoxin and play a major role in inducing pathogenicity of B. thuringiensis toxins in H. armigera.
| Item Type: | Article |
|---|---|
| Divisions: | RP-Grain Legumes |
| CRP: | CGIAR Research Program on Grain Legumes |
| Uncontrolled Keywords: | Helicoverpa armigera, Midgut bacteria, Proteases, Cry1Ac proteins, Transgenics, Helicoverpa |
| Subjects: | Others > Helicoverpa Others |
| Depositing User: | Mr Ramesh K |
| Date Deposited: | 14 Oct 2016 05:06 |
| Last Modified: | 17 Oct 2016 09:04 |
| URI: | http://oar.icrisat.org/id/eprint/9736 |
| Official URL: | http://dx.doi.org/10.3389/fmicb.2016.01567 |
| Projects: | UNSPECIFIED |
| Funders: | University Grants Commission (UGC) |
| Acknowledgement: | We thank the staff, Insect Rearing Laboratory, Entomology, for providing the insects throughout the study. Mr. VR would like to thank University Grants Commission (UGC), New Delhi, India for the financial assistance in the mode of BSR fellowship in science for meritorious students. We thank to Dr. Arunasree, Assistant Professor, School of Life Sciences, Hyderabad Central University, Hyderabad, India, for helping in proteases sequence analysis. |
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