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https://www.readbyqxmd.com/read/27918112/validation-of-adam10-metalloprotease-as-a-bacillus-thuringiensis-cry3aa-toxin-functional-receptor-in-colorado-potato-beetle-leptinotarsa-decemlineata
#1
V M Ruiz-Arroyo, I García-Robles, C Ochoa-Campuzano, G A Goig, E Zaitseva, G Baaken, A C Martínez-Ramírez, C Rausell, M D Real
Bacillus thuringiensis parasporal crystal proteins (Cry proteins) are insecticidal pore-forming toxins that bind to specific receptor molecules on the brush border membrane of susceptible insect midgut cells to exert their toxic action. In the Colorado potato beetle (CPB), a coleopteran pest, we previously proposed that interaction of Cry3Aa toxin with a CPB ADAM10 metalloprotease is an essential part of the mode of action of this toxin. Here, we annotated the gene sequence encoding an ADAM10 metalloprotease protein (CPB-ADAM10) in the CPB genome sequencing project, and using RNA interference gene silencing we demonstrated that CPB-ADAM10 is a Cry3Aa toxin functional receptor in CPB...
December 5, 2016: Insect Molecular Biology
https://www.readbyqxmd.com/read/27888075/the-domain-ii-loops-of-bacillus-thuringiensis-cry1aa-form-an-overlapping-interaction-site-for-two-bombyx-mori-larvae-functional-receptors-abc-transporter-c2-and-cadherin-like-receptor
#2
Satomi Adegawa, Yui Nakama, Haruka Endo, Naoki Shinkawa, Shingo Kikuta, Ryoichi Sato
Information about the receptor-interaction region of Cry toxins, insecticidal proteins produced by Bacillus thuringiensis, is needed to elucidate the mode of action of Cry toxins and improve their toxicity through protein engineering. We analyzed the interaction sites on Cry1Aa with ABC transporter C2 (ABCC2), one of the most important Cry1A toxin receptors. A competitive binding assay revealed that the Bombyx mori ABCC2 (BmABCC2) Cry1A binding site was the same as the BtR175 binding site, suggesting that the loop region of Cry1Aa domain II is a binding site...
November 23, 2016: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/27867074/toxicity-of-cry1a-toxins-from-bacillus-thuringiensis-to-cf1-cells-does-not-involve-activation-of-adenylate-cyclase-pka-signaling-pathway
#3
Leivi Portugal, Carlos Muñóz-Garay, Diana L Martínez de Castro, Mario Soberón, Alejandra Bravo
Bacillus thuringiensis (Bt) bacteria produce Cry toxins that are able to kill insect pests. Different models explaining the mode of action of these toxins have been proposed. The pore formation model proposes that the toxin creates pores in the membrane of the larval midgut cells after interaction with different receptors such as cadherin, aminopeptidase N and alkaline phosphatase and that this pore formation activity is responsible for the toxicity of these proteins. The alternative model proposes that interaction with cadherin receptor triggers an intracellular cascade response involving protein G, adenylate cyclase (AC) and protein kinase A (PKA)...
November 17, 2016: Insect Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/27813251/functional-characterization-of-bacillus-thuringiensis-cry-toxin-receptors-explain-resistance-in-insects
#4
Shiho Tanaka, Haruka Endo, Satomi Adegawa, Shingo Kikuta, Ryoichi Sato
Bacillus thuringiensis produces Cry toxins, which are used as insecticides in sprays or in transgenic crops. However, little is known about the function of Cry toxin receptors and the mechanisms that determine their binding specificity and activity. In this study, the cRNAs of Bombyx mori ABC transporter C2 (BmABCC2), the toxin-binding region of cadherin-like receptor (BtR175-TBR), or aminopeptidase N1 (BmAPN1) were injected to Xenopus oocytes, and the Cry1Aa-dependent cation selective pore-formation activities of these receptors were analyzed using a two-electrode voltage clamp...
November 4, 2016: FEBS Journal
https://www.readbyqxmd.com/read/27804103/rhizobacteria-with-nematicide-aptitude-enzymes-and-compounds-associated
#5
REVIEW
C Castaneda-Alvarez, E Aballay
The use of rhizobacteria to control plant parasitic nematodes has been widely studied. Currently, the research focuses on bacteria-nematode interactions that can mitigate this complex microbiome in agriculture. Various enzymes, toxins and metabolic by-products from rhizobacteria antagonize plant parasitic nematodes, and many different modes of action have been proposed. Hydrolytic enzymes, primarily proteases, collagenases and chitinases, have been related to the nematicide effect in rhizobacteria, proving to be an important factor involved in the degradation of different chemical constituents of nematodes at distinct developmental stages...
December 2016: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/27769815/parasporins-1-and-2-their-structure-and-activity
#6
Toshihiko Akiba, Shiro Okumura
Parasporins are novel protein toxins preferentially cytotoxic against human cancer cells. They are obtained from parasporal inclusions of Bacillus thuringiensis and, accordingly, are considered congeners of the insecticidal Cry toxins. Two types of parasporins have been identified: the three-domain Cry toxin type and the β-pore-forming-toxin (β-PFT) type. Crystal structures of representative members of the two types, PS1Aa1 and PS2Aa1, have been determined and compared with those of well-studied toxins. PS1Aa1 has a typical architecture characteristic of the three-domain insecticidal Cry toxins, though it is cleaved into two polypeptides...
October 18, 2016: Journal of Invertebrate Pathology
https://www.readbyqxmd.com/read/27708457/type-of-fitness-cost-influences-the-rate-of-evolution-of-resistance-to-transgenic-bt-crops
#7
Sean C Hackett, Michael B Bonsall
The evolution of resistance to pesticides by insect pests is a significant challenge for sustainable agriculture. For transgenic crops expressing Bacillus thuringiensis (Bt), crystalline (Cry) toxins resistance evolution may be delayed by the high-dose/refuge strategy in which a non-toxic refuge is planted to promote the survival of susceptible insects. The high-dose/refuge strategy may interact with fitness costs associated with resistance alleles to further delay resistance. However, while a diverse range of fitness costs are reported in the field, they are typically represented as a fixed reduction in survival or viability which is insensitive to ecological conditions such as competition...
October 2016: Journal of Applied Ecology
https://www.readbyqxmd.com/read/27706708/characterization-of-a-novel-cry8ea3-binding-v-atpase-subunit-a-in-holotrichia-parallela
#8
W Wei, G Wei, Z Dan, Y Xiaoping, Z Yakun
Several receptor proteins of Cry toxin have been previously identified, including cadherin-like, aminopeptidase N, and alkaline phosphatase. In the present work, a novel binding protein, V-ATPase subunit A (HpVAA), was identified in Holotricia parallela larvae and characterized. We performed reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends technology to obtain the cDNA of the full-length hpvaa. Sequencing analysis showed that the open reading frame of hpvaa (GenBank accession No...
September 2, 2016: Genetics and Molecular Research: GMR
https://www.readbyqxmd.com/read/27628909/effects-and-mechanisms-of-bacillus-thuringiensis-crystal-toxins-for-mosquito-larvae
#9
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
https://www.readbyqxmd.com/read/27617345/highly-selective-and-sensitive-electrochemical-immunoassay-of-cry1c-using-nanobody-and-%C3%AF-%C3%AF-stacked-graphene-oxide-thionine-assembly
#10
Qing Zhou, Guanghui Li, Yuanjian Zhang, Min Zhu, Yakun Wan, Yanfei Shen
Cry1C is one of the emerging toxin proteins produced by the Bacillus thuringiensis in the genetically modified crops for pest control in agriculture; thus, it is vital to measure the Cry1C level in crops for the healthy and environmental concerns. Current detections of Cry1C mainly rely on instrumental analysis such as high-performance liquid chromatography, which are time-consuming and are generally cost-prohibitive. Herein, a simple nanobodies (Nbs)-based electrochemical immunosensor has been first proposed for highly selective and sensitive detection of Cry1C...
October 4, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/27576487/the-pesticidal-cry6aa-toxin-from-bacillus-thuringiensis-is-structurally-similar-to-hlye-family-alpha-pore-forming-toxins
#11
Alexey Dementiev, Jason Board, Anand Sitaram, Timothy Hey, Matthew S Kelker, Xiaoping Xu, Yan Hu, Cristian Vidal-Quist, Vimbai Chikwana, Samantha Griffin, David McCaskill, Nick X Wang, Shao-Ching Hung, Michael K Chan, Marianne M Lee, Jessica Hughes, Alice Wegener, Raffi V Aroian, Kenneth E Narva, Colin Berry
BACKGROUND: The Cry6 family of proteins from Bacillus thuringiensis represents a group of powerful toxins with great potential for use in the control of coleopteran insects and of nematode parasites of importance to agriculture. These proteins are unrelated to other insecticidal toxins at the level of their primary sequences and the structure and function of these proteins has been poorly studied to date. This has inhibited our understanding of these toxins and their mode of action, along with our ability to manipulate the proteins to alter their activity to our advantage...
2016: BMC Biology
https://www.readbyqxmd.com/read/27544649/selection-and-application-of-broad-specificity-human-domain-antibody-for-simultaneous-detection-of-bt-cry-toxins
#12
Chongxin Xu, Xiao Zhang, Xiaoqin Liu, Yuan Liu, Xiaodan Hu, Jianfeng Zhong, Cunzheng Zhang, Xianjin Liu
Bt Cry toxin is a kind of bio-toxins that used for genetically modified crops (GMC) transformation widely. In this study, total 15 positive clones could bind the Bt Cry toxins which isolated from a human domain antibody library by 5 rounds affinity selection. According to analyzing of PCR amplification and enzyme-linked immunosorbent assay (ELISA), the most positive phage domain antibody (named F5) gene was cloned into the pET26b vector and expressed in E. coli BL21. The purified antibody was used to develop an indirect competitive ELISA (IC-ELISA) for Cry1Ab, Cry1Ac, Cry1B, Cry1C and Cry1F toxins, respectively...
November 1, 2016: Analytical Biochemistry
https://www.readbyqxmd.com/read/27538933/towards-novel-cry-toxins-with-enhanced-toxicity-broader-a-new-chimeric-cry4ba-cry1ac-toxin
#13
Raida Zribi Zghal, Jihen Elleuch, Mamdouh Ben Ali, Frédéric Darriet, Ahmed Rebaï, Fabrice Chandre, Samir Jaoua, Slim Tounsi
Attempts have been made to express or to merge different Cry proteins in order to enhance toxic effects against various insects. Cry1A proteins of Bacillus thuringiensis form a typical bipyramidal parasporal crystal and their protoxins contain a highly conserved C-terminal region. A chimerical gene, called cry(4Ba-1Ac), formed by a fusion of the N-terminus part of cry4Ba and the C-terminus part of cry1Ac, was constructed. Its transformation to an acrystalliferous B. thuringiensis strain showed that it was expressed as a chimerical protein of 116 kDa, assembled in spherical to amorphous parasporal crystals...
August 18, 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27521921/proteomics-based-identification-of-midgut-proteins-correlated-with-cry1ac-resistance-in-plutella-xylostella-l
#14
Jixing Xia, Zhaojiang Guo, Zezhong Yang, Xun Zhu, Shi Kang, Xin Yang, Fengshan Yang, Qingjun Wu, Shaoli Wang, Wen Xie, Weijun Xu, Youjun Zhang
The diamondback moth, Plutella xylostella (L.), is a worldwide pest of cruciferous crops and can rapidly develop resistance to many chemical insecticides. Although insecticidal crystal proteins (i.e., Cry and Cyt toxins) derived from Bacillus thuringiensis (Bt) have been useful alternatives to chemical insecticides for the control of P. xylostella, resistance to Bt in field populations of P. xylostella has already been reported. A better understanding of the resistance mechanisms to Bt should be valuable in delaying resistance development...
September 2016: Pesticide Biochemistry and Physiology
https://www.readbyqxmd.com/read/27518813/genetic-basis-of-cry1f-resistance-in-a-laboratory-selected-asian-corn-borer-strain-and-its-cross-resistance-to-other-bacillus-thuringiensis-toxins
#15
Yueqin Wang, Yidong Wang, Zhenying Wang, Alejandra Bravo, Mario Soberón, Kanglai He
The Asian corn borer (ACB), Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae), is the most destructive insect pest of corn in China. Susceptibility to the Cry1F toxin derived from Bacillus thuringiensis has been demonstrated for ACB, suggesting the potential for Cry1F inclusion as part of an insect pest management program. Insects can develop resistance to Cry toxins, which threatens the development and use of Bt formulations and Bt crops in the field. To determine possible resistance mechanisms to Cry1F, a Cry1F-resistant colony of ACB (ACB-FR) that exhibited more than 1700-fold resistance was established through selection experiments after 49 generations of selection under laboratory conditions...
2016: PloS One
https://www.readbyqxmd.com/read/27506800/midgut-microbiota-and-host-immunocompetence-underlie-bacillus-thuringiensis-killing-mechanism
#16
Silvia Caccia, Ilaria Di Lelio, Antonietta La Storia, Adriana Marinelli, Paola Varricchio, Eleonora Franzetti, Núria Banyuls, Gianluca Tettamanti, Morena Casartelli, Barbara Giordana, Juan Ferré, Silvia Gigliotti, Danilo Ercolini, Francesco Pennacchio
Bacillus thuringiensis is a widely used bacterial entomopathogen producing insecticidal toxins, some of which are expressed in insect-resistant transgenic crops. Surprisingly, the killing mechanism of B. thuringiensis remains controversial. In particular, the importance of the septicemia induced by the host midgut microbiota is still debated as a result of the lack of experimental evidence obtained without drastic manipulation of the midgut and its content. Here this key issue is addressed by RNAi-mediated silencing of an immune gene in a lepidopteran host Spodoptera littoralis, leaving the midgut microbiota unaltered...
August 23, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27473845/conditions-for-homogeneous-preparation-of-stable-monomeric-and-oligomeric-forms-of-activated-vip3a-toxin-from-bacillus-thuringiensis
#17
Thittaya Kunthic, Wahyu Surya, Boonhiang Promdonkoy, Jaume Torres, Panadda Boonserm
Bacillus thuringiensis vegetative insecticidal proteins like Vip3A have been used for crop protection and to delay resistance to existing insecticidal Cry toxins. However, little is known about Vip3A's behavior or its mechanism of action, and a structural model is required. Herein, in an effort to facilitate future crystallization and functional studies, we have used the orthogonal biophysical techniques of light scattering and sedimentation to analyze the aggregation behavior and stability of trypsin-activated Vip3A toxin in solution...
July 29, 2016: European Biophysics Journal: EBJ
https://www.readbyqxmd.com/read/27456115/three-toxins-two-receptors-one-mechanism-mode-of-action-of-cry1a-toxins-from-bacillus-thuringiensis-in-heliothis-virescens
#18
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
https://www.readbyqxmd.com/read/27452121/cry1ab-expressing-rice-did-not-influence-expression-of-fecundity-related-genes-in-the-wolf-spider-pardosa-pseudoannulata
#19
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
https://www.readbyqxmd.com/read/27436734/bacillus-thuringiensis-toxin-resistance-mechanisms-among-lepidoptera-progress-on-genomic-approaches-to-uncover-causal-mutations-in-the-european-corn-borer-ostrinia-nubilalis
#20
REVIEW
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
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