Tags

Type your tag names separated by a space and hit enter

Resistance of Helicoverpa armigera to Cry1Ac toxin from Bacillus thuringiensis is due to improper processing of the protoxin.
Biochem J. 2009 Apr 15; 419(2):309-16.BJ

Abstract

The bacterium Bacillus thuringiensis produces ICPs (insecticidal crystal proteins) that are deposited in their spore mother cells. When susceptible lepidopteran larvae ingest these spore mother cells, the ICPs get solubilized in the alkaline gut environment. Of approx. 140 insecticidal proteins described thus far, insecticidal protein Cry1Ac has been applied extensively as the main ingredient of spray formulation as well as the principal ICP introduced into crops as transgene for agricultural crop protection. The 135 kDa Cry1Ac protein, upon ingestion by the insect, is processed successively at the N- and C-terminus by the insect midgut proteases to generate a 65 kDa bioactive core protein. The activated core protein interacts with specific receptors located at the midgut epithilium resulting in the lysis of cells and eventual death of the larvae. A laboratory-reared population of Helicoverpa armigera displayed 72-fold resistance to the B. thuringiensis insecticidal protein Cry1Ac. A careful zymogram analysis of Cry1Ac-resistant insects revealed an altered proteolytic profile. The altered protease profile resulted in improper processing of the insecticidal protein and as a consequence increased the LC50 concentrations of Cry1Ac. The 135 kDa protoxin-susceptible insect larval population processed the protein to the biologically active 65 kDa core protein, while the resistant insect larval population yielded a mixture of 95 kDa and 68 kDa Cry1Ac polypeptides. N-terminal sequencing of these 95 and 68 kDa polypeptides produced by gut juices of resistant insects revealed an intact N-terminus. Protease gene transcription profiling by semi-quantitative RT (reverse transcription)-PCR led to the identification of a down-regulated HaSP2 (H. armigera serine protease 2) in the Cry1Ac-resistant population. Protease HaSP2 was cloned, expressed and demonstrated to be responsible for proper processing of insecticidal protoxin. The larval population displaying resistance to Cry1Ac do not show an altered sensitivity against another insecticidal protein, Cry2Ab. The implications of these observations in the context of the possibility of development of resistance and its management in H. armigera to Cry1Ac through transgenic crop cultivation are discussed.

Links

Publisher Full Text (DOI)

Authors+Show Affiliations

Rajagopal R
Insect Resistance Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi 110 067, India.
Arora N
No affiliation info available
Sivakumar S
No affiliation info available
Rao NG
No affiliation info available
Nimbalkar SA
No affiliation info available
Bhatnagar RK
No affiliation info available

MeSH

Amino Acid SequenceAnimalsAnimals, NewbornBacillus thuringiensis ToxinsBacterial ProteinsEndotoxinsGossypiumHemolysin ProteinsLepidopteraMolecular Sequence DataPeptide HydrolasesPlants, Genetically ModifiedReverse Transcriptase Polymerase Chain ReactionSequence Homology, Amino AcidSerine Endopeptidases

Pub Type(s)

Journal Article

Language

eng

PubMed ID

19146482

Citation

Rajagopal, Raman, et al. "Resistance of Helicoverpa Armigera to Cry1Ac Toxin From Bacillus Thuringiensis Is Due to Improper Processing of the Protoxin." The Biochemical Journal, vol. 419, no. 2, 2009, pp. 309-16.
Rajagopal R, Arora N, Sivakumar S, et al. Resistance of Helicoverpa armigera to Cry1Ac toxin from Bacillus thuringiensis is due to improper processing of the protoxin. Biochem J. 2009;419(2):309-16.
Rajagopal, R., Arora, N., Sivakumar, S., Rao, N. G., Nimbalkar, S. A., & Bhatnagar, R. K. (2009). Resistance of Helicoverpa armigera to Cry1Ac toxin from Bacillus thuringiensis is due to improper processing of the protoxin. The Biochemical Journal, 419(2), 309-16. https://doi.org/10.1042/BJ20081152
Rajagopal R, et al. Resistance of Helicoverpa Armigera to Cry1Ac Toxin From Bacillus Thuringiensis Is Due to Improper Processing of the Protoxin. Biochem J. 2009 Apr 15;419(2):309-16. PubMed PMID: 19146482.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Resistance of Helicoverpa armigera to Cry1Ac toxin from Bacillus thuringiensis is due to improper processing of the protoxin. AU - Rajagopal,Raman, AU - Arora,Naresh, AU - Sivakumar,Swaminathan, AU - Rao,Nagarjun G V, AU - Nimbalkar,Sharad A, AU - Bhatnagar,Raj K, PY - 2009/1/17/entrez PY - 2009/1/17/pubmed PY - 2009/4/15/medline SP - 309 EP - 16 JF - The Biochemical journal JO - Biochem J VL - 419 IS - 2 N2 - The bacterium Bacillus thuringiensis produces ICPs (insecticidal crystal proteins) that are deposited in their spore mother cells. When susceptible lepidopteran larvae ingest these spore mother cells, the ICPs get solubilized in the alkaline gut environment. Of approx. 140 insecticidal proteins described thus far, insecticidal protein Cry1Ac has been applied extensively as the main ingredient of spray formulation as well as the principal ICP introduced into crops as transgene for agricultural crop protection. The 135 kDa Cry1Ac protein, upon ingestion by the insect, is processed successively at the N- and C-terminus by the insect midgut proteases to generate a 65 kDa bioactive core protein. The activated core protein interacts with specific receptors located at the midgut epithilium resulting in the lysis of cells and eventual death of the larvae. A laboratory-reared population of Helicoverpa armigera displayed 72-fold resistance to the B. thuringiensis insecticidal protein Cry1Ac. A careful zymogram analysis of Cry1Ac-resistant insects revealed an altered proteolytic profile. The altered protease profile resulted in improper processing of the insecticidal protein and as a consequence increased the LC50 concentrations of Cry1Ac. The 135 kDa protoxin-susceptible insect larval population processed the protein to the biologically active 65 kDa core protein, while the resistant insect larval population yielded a mixture of 95 kDa and 68 kDa Cry1Ac polypeptides. N-terminal sequencing of these 95 and 68 kDa polypeptides produced by gut juices of resistant insects revealed an intact N-terminus. Protease gene transcription profiling by semi-quantitative RT (reverse transcription)-PCR led to the identification of a down-regulated HaSP2 (H. armigera serine protease 2) in the Cry1Ac-resistant population. Protease HaSP2 was cloned, expressed and demonstrated to be responsible for proper processing of insecticidal protoxin. The larval population displaying resistance to Cry1Ac do not show an altered sensitivity against another insecticidal protein, Cry2Ab. The implications of these observations in the context of the possibility of development of resistance and its management in H. armigera to Cry1Ac through transgenic crop cultivation are discussed. SN - 1470-8728 UR - https://www.unboundmedicine.com/medline/citation/19146482/Resistance_of_Helicoverpa_armigera_to_Cry1Ac_toxin_from_Bacillus_thuringiensis_is_due_to_improper_processing_of_the_protoxin_ DB - PRIME DP - Unbound Medicine ER -