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Bacillus thuringiensis receptors

Xiaoye Liu, Shuangyang Ding, Peijie Shi, Richard Dietrich, Erwin Märtlbauer, Kui Zhu
Bacillus cereus is an opportunistic pathogen that often causes foodborne infectious diseases and food poisoning. Non-haemolytic enterotoxin (Nhe) is the major toxin found in almost all enteropathogenic B. cereus and B. thuringiensis isolates. However, little is known about the cellular response after Nhe triggered pore formation on cell membrane. Here we demonstrate that Nhe induced cell cycle arrest at G0 /G1 phase and provoked apoptosis in Vero cells, most likely associated with mitogen-activated protein kinase (MAPK) and death receptor pathways...
October 20, 2016: Cellular Microbiology
Viviana P Rubio, Alejandra Bravo, Jorge Olmos
In this work we isolated a Surface-Layer-Protein (SLP) from a Bacillus thuringiensis (Bt) strain to evaluate it cytotoxic effects against MDA-MB-231 human breast cancer cells. AP11 was selected from a group of Bt strains using SLP oligonucleotides developed from Bacillus conserved regions. AP11 strain was grown in Luria Bertani (LB) medium until late exponential phase; an 86 kDa protein was extracted using 5 M LiCl and identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). It corresponded to a multispecies S-layer protein highly similar to previously described SLP in B...
October 6, 2016: Journal of Microbiology and Biotechnology
Patricia Hernández-Martínez, Natalia Mara Vera-Velasco, Baltasar Escriche
Bacillus thuringiensis Cry3Aa and Cry3Ca proteins have been reported to be toxic against the African sweetpotato pest Cylas puncticollis. In the present work, the binding sites of these proteins in C. puncticollis brush border vesicles suggest the occurrence of different binding sites, but only one of them is shared. Our results suggest that pest resistance mediated by alteration of the shared Cry-receptor binding site might not render both Cry proteins ineffective.
September 20, 2016: Toxicon: Official Journal of the International Society on Toxinology
Qi Zhang, Gang Hua, Michael J Adang
Bacillus thuringiensis is a gram-positive aerobic bacterium that produces insecticidal crystalline inclusions during sporulation phases of the mother cell. The virulence factor, known as parasporal crystals, is composed of Cry and Cyt toxins. Cry toxins display a common three-domain topology. Cry toxins exert intoxication through toxin activation, receptor binding and pore formation in suitable larval gut environment. The mosquitocidal toxins, Bt subsp. israelensis (Bti) and was found highly active against mosquito larvae and are widely used in pesticide market for vector control...
September 15, 2016: Insect Science
Anne Bretschneider, David G Heckel, Yannick Pauchet
Insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) are highly active against Lepidoptera. However, field-evolved resistance to Bt toxins is on the rise. The 12-cadherin domain protein HevCaLP and the ABC transporter HevABCC2 are both genetically linked to Cry toxin resistance in Heliothis virescens. We investigated their interaction using stably expressing non-lytic clonal Sf9 cell lines expressing either protein or both together. Untransfected Sf9 cells are innately sensitive to Cry1Ca toxin, but not to Cry1A toxins; and quantitative PCR revealed negligible expression of genes involved in Cry1A toxicity such as cadherin, ABCC2, alkaline phosphatase (ALP) and aminopeptidase N (APN)...
September 2016: Insect Biochemistry and Molecular Biology
Juan Wang, Yuan-De Peng, Chao He, Bao-Yang Wei, Yun-Shan Liang, Hui-Lin Yang, Zhi Wang, David Stanley, Qi-Sheng Song
The impact of Bacillus thuringiensis (Bt) toxin proteins on non-target predatory arthropods is not well understood at the cellular and molecular levels. Here, we investigated the potential effects of Cry1Ab expressing rice on fecundity of the wolf spider, Pardosa pseudoannulata, and some of the underlying molecular mechanisms. The results indicated that brown planthoppers (BPHs) reared on Cry1Ab-expressing rice accumulated the Cry toxin and that reproductive parameters (pre-oviposition period, post-oviposition stage, number of eggs, and egg hatching rate) of the spiders that consumed BPHs reared on Bt rice were not different from those that consumed BPHs reared on the non-Bt control rice...
October 30, 2016: Gene
Brad S Coates
Transgenic plants that express Bacillus thuringiensis (Bt) crystal (Cry) protein toxins (Bt crops) effectively control feeding by the European corn borer, Ostrinia nubilalis, although documented resistance evolution among a number of species in both the laboratory and field has heightened concerns about the durability of this technology. Research has provided major insights into the mutations that alter Bt toxin binding receptor structure and function within the midgut of Lepidoptera that directly impacts the efficacy of Bt toxins, and potentially leads to the evolution of resistance to Bt crops in the field...
June 2016: Current Opinion in Insect Science
Renaud Stalinski, Frederic Laporte, Guillaume Tetreau, Laurence Després
Bacillus thuringiensis israelensis (Bti) toxins are increasingly used for mosquito control, but little is known about the precise mode of action of each of these toxins, and how they interact to kill mosquito larvae. By using RNA sequencing, we investigated change in gene transcription level and polymorphism variations associated with resistance to each Bti Cry toxin and to the full Bti toxin mixture in the dengue vector Aedes aegypti. The up-regulation of genes related to chitin metabolism in all selected strain suggests a generalist, non-toxin-specific response to Bti selection in Aedes aegypti...
October 2016: Infection, Genetics and Evolution
Jing Wang, Haonan Zhang, Huidong Wang, Shan Zhao, Yayun Zuo, Yihua Yang, Yidong Wu
Cadherins have been identified as receptors of Bacillus thuringiensis (Bt) Cry1A toxins in several lepidopteran insects including the cotton bollworm, Helicoverpa armigera. Disruption of the cadherin gene HaCad has been genetically linked to resistance to Bt toxin Cry1Ac in H. armigera. By using the CRISPR/Cas9 genome editing system (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9), HaCad from the Cry1Ac-susceptible SCD strain of H. armigera was successfully knocked out...
September 2016: Insect Biochemistry and Molecular Biology
Erica E Tassone, Gina Zastrow-Hayes, John Mathis, Mark E Nelson, Gusui Wu, J Lindsey Flexner, Yves Carrière, Bruce E Tabashnik, Jeffrey A Fabrick
BACKGROUND: The pink bollworm Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) is one of the world's most important pests of cotton. Insecticide sprays and transgenic cotton producing toxins of the bacterium Bacillus thuringiensis (Bt) are currently used to manage this pest. Bt toxins kill susceptible insects by specifically binding to and destroying midgut cells, but they are not toxic to most other organisms. Pink bollworm is useful as a model for understanding insect responses to Bt toxins, yet advances in understanding at the molecular level have been limited because basic genomic information is lacking for this cosmopolitan pest...
2016: GigaScience
Jelena Radosavljevic, Samir Naimov
The activity of seven Cry1, one Cry9 and one hybrid Cry1 protoxins against neonate larvae of summer fruit tortrix (Adoxophyes orana - Fischer von Rösslerstamm) has been investigated. Cry1Ia is identified as the most toxic protein, followed by Cry1Aa and Cry1Ac. Cry1Ca, Cry1Cb, Cry1Da and Cry1Fa were less active, while SN19 (Cry1 hybrid protein with domain composition 1Ba/1Ia/1Ba) and Cry9Aa exhibited negligible toxicity against A. orana. In vitro trypsin-activated Cry1Ac is still less active than Cry1Ia protoxin, suggesting that toxicity of Cry1Ia is most probably due to more complex differences in further downstream processing, toxin-receptor interactions and pore formation in A...
July 2016: Journal of Invertebrate Pathology
William J Moar, Adam J Evans, Colton R Kessenich, James A Baum, David J Bowen, Thomas C Edrington, Jeffrey A Haas, Jean-Louis K Kouadio, James K Roberts, Andre Silvanovich, Yong Yin, Brian E Weiner, Kevin C Glenn, Matthew L Odegaard
The need for sustainable insect pest control is driving the investigation and discovery of insecticidal proteins outside of the typical 3- domain Cry protein family from Bacillus thuringiensis (Bt). Examples include Cry35 and Cry51 that belong to protein families (Toxin_10, ETX_MTX2) sharing a common β-pore forming structure and function with known mammalian toxins such as epsilon toxin (ETX). Although β-pore forming proteins are related to mammalian toxins, there are key differences in sequence and structure that lead to organism specificity that is useful in the weight-of-evidence approach for safety assessment...
May 25, 2016: Journal of Invertebrate Pathology
Dandan Zhang, Yutao Xiao, Khalid Hussain Dhiloo, Mario Soberon, Alejandra Bravo, Kongming Wu
Glycosphingolipids (GSLs) play important roles in the cellular biology of vertebrate and invertebrate organisms, such as cell differentiation, tumor metastasis, and cell coordination. GSLs also serve as receptors for different bacterial toxins. For example, in the nematode Caenorhabditis elegans, GSLs function as receptors of the insecticidal Cry toxins produced by Bacillus thuringiensis (Bt), and mutations in bre genes involved in GSLs synthesis resulted in resistance to Cry5 toxin in this organism. However, the information of GSLs function in insects is still limited...
May 17, 2016: Journal of Economic Entomology
Ahmed H Badran, Victor M Guzov, Qing Huai, Melissa M Kemp, Prashanth Vishwanath, Wendy Kain, Autumn M Nance, Artem Evdokimov, Farhad Moshiri, Keith H Turner, Ping Wang, Thomas Malvar, David R Liu
The Bacillus thuringiensis δ-endotoxins (Bt toxins) are widely used insecticidal proteins in engineered crops that provide agricultural, economic, and environmental benefits. The development of insect resistance to Bt toxins endangers their long-term effectiveness. Here we have developed a phage-assisted continuous evolution selection that rapidly evolves high-affinity protein-protein interactions, and applied this system to evolve variants of the Bt toxin Cry1Ac that bind a cadherin-like receptor from the insect pest Trichoplusia ni (TnCAD) that is not natively bound by wild-type Cry1Ac...
May 5, 2016: Nature
Maissa Chakroun, Núria Banyuls, Tom Walsh, Sharon Downes, Bill James, Juan Ferré
Crops expressing genes from Bacillus thuringiensis (Bt crops) are among the most successful technologies developed for the control of pests but the evolution of resistance to them remains a challenge. Insect resistant cotton and maize expressing the Bt Vip3Aa protein were recently commercialized, though not yet in Australia. We found that, although relatively high, the frequency of alleles for resistance to Vip3Aa in field populations of H. armigera in Australia did not increase over the past four seasons until 2014/15...
2016: Scientific Reports
Rania Nakad, L Basten Snoek, Wentao Yang, Sunna Ellendt, Franziska Schneider, Timm G Mohr, Lone Rösingh, Anna C Masche, Philip C Rosenstiel, Katja Dierking, Jan E Kammenga, Hinrich Schulenburg
BACKGROUND: The invertebrate immune system comprises physiological mechanisms, physical barriers and also behavioral responses. It is generally related to the vertebrate innate immune system and widely believed to provide nonspecific defense against pathogens, whereby the response to different pathogen types is usually mediated by distinct signalling cascades. Recent work suggests that invertebrate immune defense can be more specific at least at the phenotypic level. The underlying genetic mechanisms are as yet poorly understood...
2016: BMC Genomics
Maissa Chakroun, Núria Banyuls, Yolanda Bel, Baltasar Escriche, Juan Ferré
Entomopathogenic bacteria produce insecticidal proteins that accumulate in inclusion bodies or parasporal crystals (such as the Cry and Cyt proteins) as well as insecticidal proteins that are secreted into the culture medium. Among the latter are the Vip proteins, which are divided into four families according to their amino acid identity. The Vip1 and Vip2 proteins act as binary toxins and are toxic to some members of the Coleoptera and Hemiptera. The Vip1 component is thought to bind to receptors in the membrane of the insect midgut, and the Vip2 component enters the cell, where it displays its ADP-ribosyltransferase activity against actin, preventing microfilament formation...
June 2016: Microbiology and Molecular Biology Reviews: MMBR
Shiho Tanaka, Kazuhisa Miyamoto, Hiroaki Noda, Haruka Endo, Shingo Kikuta, Ryoichi Sato
In a previous report, seven Cry1Ab-resistant strains were identified in the silkworm, Bombyx mori; these strains were shown to have a tyrosine insertion at position 234 in extracellular loop 2 of the ABC transporter C2 (BmABCC2). This insertion was confirmed to destroy the receptor function of BmABCC2 and confer the strains resistance against Cry1Ab and Cry1Ac. However, these strains were susceptible to Cry1Aa. In this report, we examined the mechanisms of the loss of receptor function of the transporter by expressing mutations in Sf9 cells...
April 2016: Peptides
Jihen Elleuch, Samir Jaoua, Carole Ginibre, Fabrice Chandre, Slim Tounsi, Raida Z Zghal
BACKGROUND: Bacillus thuringiensis δ-endotoxins are the most widely used biopesticides for controlling economically important crop pests and disease vectors. Improving its efficacy is of great benefit. Here, an improvement of Cry2Aa δ-endotoxins toxicity was conducted via a cry gene over-expression system using P20 from B. thuringiensis israelensis. RESULTS: The co-expression of Cry2Aa with P20 witnessed a 7-fold increase of its production yield in B. thuringiensis...
February 22, 2016: Pest Management Science
W Maik, M A Abid, H M N Cheema, A A Khan, M Z Iqbal, A Qayyum, M Hanif, N Bibi, S N Yuan, A Yasmeen, A Mahmood, J Ashraf
Cotton has unique history of domestication, diversification, and utilization. Globally it is an important cash crop that provides raw material for textile industry. The story of cotton started from human civilization and the climax arrived with the efforts of developing transgenic cotton for various traits. Though conventional breeding brought steady improvement in developing resistance against biotic stresses but recent success story of gene transferfrom Bacillus thuringiensis into cotton showed game changing effects on cotton cultivation...
November 2015: T︠S︡itologii︠a︡ i Genetika
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