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Sato R. Utilization of Diverse Molecules as Receptors by Cry Toxin and the Promiscuous Nature of Receptor-Binding Sites Which Accounts for the Diversity. Biomolecules 2024; 14:425. [PMID: 38672442 PMCID: PMC11048593 DOI: 10.3390/biom14040425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 04/28/2024] Open
Abstract
By 2013, it had been shown that the genes cadherin-like receptor (Cad) and ATP-binding cassette transporter subfamily C2 (ABCC2) were responsible for insect resistance to several Cry1A toxins, acting as susceptibility-determining receptors, and many review articles have been published. Therefore, this review focuses on information about receptors and receptor-binding sites that have been revealed since 2014. Since 2014, studies have revealed that the receptors involved in determining susceptibility vary depending on the Cry toxin subfamily, and that binding affinity between Cry toxins and receptors plays a crucial role. Consequently, models have demonstrated that ABCC2, ABCC3, and Cad interact with Cry1Aa; ABCC2 and Cad with Cry1Ab and Cry1Ac; ABCC2 and ABCC3 with Cry1Fa; ABCB1 with Cry1Ba, Cry1Ia, Cry9Da, and Cry3Aa; and ABCA2 with Cry2Aa and Cry2Ba, primarily in the silkworm, Bombyx mori. Furthermore, since 2017, it has been suggested that the binding sites of BmCad and BmABCC2 on Cry1Aa toxin overlap in the loop region of domain II, indicating that Cry toxins use various molecules as receptors due to their ability to bind promiscuously in this region. Additionally, since 2017, several ABC transporters have been identified as low-efficiency receptors that poorly induce cell swelling in heterologously expressing cultured cells. In 2024, research suggested that multiple molecules from the ABC transporter subfamily, including ABCC1, ABCC2, ABCC3, ABCC4, ABCC10, and ABCC11, act as low-efficiency receptors for a single Cry toxin in the midgut of silkworm larvae. This observation led to the hypothesis that the presence of such low-efficiency receptors contributes to the evolution of Cry toxins towards the generation of highly functional receptors that determine the susceptibility of individual insects. Moreover, this evolutionary process is considered to offer valuable insights for the engineering of Cry toxins to overcome resistance and develop countermeasures against resistance.
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Affiliation(s)
- Ryoichi Sato
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei 184-8588, Tokyo, Japan
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Pinos D, Millán-Leiva A, Ferré J, Hernández-Martínez P. New Paralogs of the Heliothis virescens ABCC2 Transporter as Potential Receptors for Bt Cry1A Proteins. Biomolecules 2024; 14:397. [PMID: 38672415 PMCID: PMC11047971 DOI: 10.3390/biom14040397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 03/21/2024] [Indexed: 04/28/2024] Open
Abstract
The ATP-binding cassette (ABC) transporters are a superfamily of membrane proteins. These active transporters are involved in the export of different substances such as xenobiotics. ABC transporters from subfamily C (ABCC) have also been described as functional receptors for different insecticidal proteins from Bacillus thuringiensis (Bt) in several lepidopteran species. Numerous studies have characterized the relationship between the ABCC2 transporter and Bt Cry1 proteins. Although other ABCC transporters sharing structural and functional similarities have been described, little is known of their role in the mode of action of Bt proteins. For Heliothis virescens, only the ABCC2 transporter and its interaction with Cry1A proteins have been studied to date. Here, we have searched for paralogs to the ABCC2 gene in H. virescens, and identified two new ABC transporter genes: HvABCC3 and HvABCC4. Furthermore, we have characterized their gene expression in the midgut and their protein topology, and compared them with that of ABCC2. Finally, we discuss their possible interaction with Bt proteins by performing protein docking analysis.
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Affiliation(s)
- Daniel Pinos
- Departamento de Genética, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (A.M.-L.); (J.F.)
| | - Anabel Millán-Leiva
- Departamento de Genética, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (A.M.-L.); (J.F.)
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, 46113 Valencia, Spain
| | - Juan Ferré
- Departamento de Genética, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (A.M.-L.); (J.F.)
| | - Patricia Hernández-Martínez
- Departamento de Genética, Instituto de Biotecnología y Biomedicina (BIOTECMED), Universitat de València, 46100 Burjassot, Spain; (D.P.); (A.M.-L.); (J.F.)
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3
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Iwabuchi K, Miyamoto K, Jouraku A, Takasu Y, Iizuka T, Adegawa S, Li X, Sato R, Watanabe K. ABC transporter subfamily B1 as a susceptibility determinant of Bombyx mori larvae to Cry1Ba, Cry1Ia and Cry9Da toxins. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2023; 163:104030. [PMID: 37952901 DOI: 10.1016/j.ibmb.2023.104030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 10/05/2023] [Accepted: 10/28/2023] [Indexed: 11/14/2023]
Abstract
ATP binding cassette (ABC) transporters are a diverse family of transmembrane proteins. Specific subfamily members expressed in the lepidopteran midgut can act as susceptibility determinants for several insecticidal Bt Cry proteins. However, the susceptibility determinants to many Cry toxins still remain unclear. Therefore, we knocked out a series of ABC transporters that are highly expressed in the midgut of Bombyx mori larvae by transcription activator-like effector nuclease (TALEN)-mediated gene editing, and the lineages that became resistant to Cry toxins were searched by toxin overlay bioassay. As a result, the B. mori ABC transporter subfamily B1 (BmABCB1) knockout lineage showed 19.17-fold resistance to Cry1Ba, 876.2-fold resistance to Cry1Ia, and 29.1-fold resistance to Cry9Da, suggesting that BmABCB1 is the determinant of susceptibility to these toxins. BmABCC2 and BmABCC3 have been shown to be susceptibility determinants based on their function as receptors. Therefore, we next heterologously expressed these ABC transporters in HEK293T cells and performed a cell swelling assay to examine whether these molecules could exert receptor functions. As a result, BmABCB1-expressing cells showed swelling response to Cry1Ia and Cry9Da, and cells expressing PxABCB1, which is the Plutella xylostella ortholog of BmABCB1, showed swelling for Cry1Ba, suggesting that ABCB1 is a susceptibility determinant by functioning as a receptor to these toxins. Furthermore, in order to clarify how high binding affinity is based on receptor function, we performed surface plasmon resonance analysis and found that each KD of Cry1Ba, Cry1Ia, and Cry9Da to BmABCB1 were 7.69 × 10-8 M, 2.19 × 10-9 M, and 4.17 × 10-6 M respectively.
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Affiliation(s)
- Kana Iwabuchi
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo, 184-8588, Japan
| | - Kazuhisa Miyamoto
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Akiya Jouraku
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Yoko Takasu
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Tetsuya Iizuka
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Satomi Adegawa
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo, 184-8588, Japan
| | - Xiaoyi Li
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo, 184-8588, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo, 184-8588, Japan.
| | - Kenji Watanabe
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki, 305-8634, Japan.
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Endo H. Molecular and Kinetic Models for Pore Formation of Bacillus thuringiensis Cry Toxin. Toxins (Basel) 2022; 14:toxins14070433. [PMID: 35878171 PMCID: PMC9321905 DOI: 10.3390/toxins14070433] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/03/2022] [Accepted: 06/22/2022] [Indexed: 02/05/2023] Open
Abstract
Cry proteins from Bacillus thuringiensis (Bt) and other bacteria are pesticidal pore-forming toxins. Since 2010, when the ABC transporter C2 (ABCC2) was identified as a Cry1Ac protein resistant gene, our understanding of the mode of action of Cry protein has progressed substantially. ABCC2 mediates high Cry1A toxicity because of its high activity for helping pore formation. With the discovery of ABCC2, the classical killing model based on pore formation and osmotic lysis became nearly conclusive. Nevertheless, we are still far from a complete understanding of how Cry proteins form pores in the cell membrane through interactions with their host gut membrane proteins, known as receptors. Why does ABCC2 mediate pore formation with high efficiency unlike other Cry1A-binding proteins? Is the “prepore” formation indispensable for pore formation? What is the mechanism underlying the synergism between ABCC2 and the 12-cadherin domain protein? We examine potential mechanisms of pore formation via receptor interactions in this paper by merging findings from prior studies on the Cry mode of action before and after the discovery of ABC transporters as Cry protein receptors. We also attempt to explain Cry toxicity using Cry–receptor binding affinities, which successfully predicts actual Cry toxicity toward cultured cells coexpressing ABC transporters and cadherin.
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Affiliation(s)
- Haruka Endo
- Department of Integrated Bioscience, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8562, Japan
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5
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Bacillus thuringiensis Cry1Ac Protoxin and Activated Toxin Exert Differential Toxicity Due to a Synergistic Interplay of Cadherin with ABCC Transporters in the Cotton Bollworm. Appl Environ Microbiol 2022; 88:e0250521. [PMID: 35262369 DOI: 10.1128/aem.02505-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacillus thuringiensis Cry proteins are used worldwide for insect control. It was proposed that Cry-protoxins must be converted into activated toxin by proteases to bind midgut cell proteins to kill insects. However, Cry-protoxins also bind to midgut proteins and kill insects that have evolved resistance to activated toxins suggesting an independent toxicity pathway. Cadherin (CAD) and ABCC transporters are recognized as important receptors for Cry proteins. Here we constructed different Helicoverpa armigera mutations in these receptors by CRISPR/Cas9. HaCAD-KO mutant showed much higher resistance to Cry1Ac activated toxin than to Cry1Ac protoxin. In contrast, the HaABCC2-M and HaABCC3-M mutants showed higher resistance to Cry1Ac-protoxin than to activated toxin. However, in the double HaABCC2/3-KO mutant, very high levels of resistance were observed to both Cry1Ac protoxin and activated toxin, supporting that both ABC transporters have redundant functions for these two proteins. In addition, Hi5 cells transfected with HaCAD were susceptible only to the activated toxin but not to protoxin. In contrast, both forms of Cry1Ac were similarly toxic to Hi5 cells expressing HaABCC2 or HaABCC3. Co-expression of HaCAD with HaABCC2 or HaABCC3 revealed a more important synergistic effect for activated toxin compared to protoxin. Overall, our results show that toxicity of Cry1Ac activated toxin involves synergistic interplay of HaCAD with ABCC transporters, while the Cry1Ac protoxin toxicity is mainly mediated by ABCC transporters with little participation of HaCAD. These data help to understand the mode of action of Cry proteins that will be relevant to enhance efficacy and durability of Bt-crops. IMPORTANCE Better understanding of the mode of action of Bacillus thuringiensis toxins is beneficial for the sustainable application of Bt crops. It is generally accepted that Cry-protoxins need to be activated by proteases to bind with midgut cell proteins and exert toxicity against insects. Here, we provide new insights into the toxic pathway of Cry proteins in the cotton bollworm. First, our results demonstrate that Cry1Ac protoxin is able to exert cytotoxicity against the insect cells expressing ABCC transporters. Second, we reveal that CAD plays a critical role in the different toxicity of protoxin and toxin by facilitating a synergistic interplay with ABCC transporters. Our results provide in vivo and in vitro experimental evidence supporting that Cry1Ac protoxin exerts toxicity against H. armigera via different steps from that of toxin. These new findings on the mode of action of Cry proteins could be beneficial for efficacy enhancement and durability of Bt-crops.
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Franz L, Raming K, Nauen R. Recombinant Expression of ABCC2 Variants Confirms the Importance of Mutations in Extracellular Loop 4 for Cry1F Resistance in Fall Armyworm. Toxins (Basel) 2022; 14:toxins14020157. [PMID: 35202184 PMCID: PMC8878193 DOI: 10.3390/toxins14020157] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 01/15/2023] Open
Abstract
Fall armyworm (FAW), Spodoptera frugiperda, is a highly destructive and invasive global noctuid pest. Its control is based on insecticide applications and Bacillus thuringiensis (Bt) insecticidal Cry toxins expressed in transgenic crops, such as Cry1F in Bt corn. Continuous selection pressure has resulted in populations that are resistant to Bt corn, particularly in Brazil. FAW resistance to Cry1F was recently shown to be conferred by mutations of ATP-binding cassette transporter C2 (ABCC2), but several mutations, particularly indels in extracellular loop 4 (ECL4), are not yet functionally validated. We addressed this knowledge gap by baculovirus-free insect cell expression of ABCC2 variants (and ABCC3) by electroporation technology and tested their response to Cry1F, Cry1A.105 and Cry1Ab. We employed a SYTOXTM orange cell viability test measuring ABCC2-mediated Bt toxin pore formation. In total, we tested seven different FAW ABCC2 variants mutated in ECL4, two mutants modified in nucleotide binding domain (NBD) 2, including a deletion mutant lacking NBD2, and S. frugiperda ABCC3. All tested ECL4 mutations conferred high resistance to Cry1F, but much less to Cry1A.105 and Cry1Ab, whereas mutations in NBD2 hardly affected Bt toxin activity. Our study confirms the importance of indels in ECL4 for Cry1F resistance in S. frugiperda ABCC2.
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Sun D, Zhu L, Guo L, Wang S, Wu Q, Crickmore N, Zhou X, Bravo A, Soberón M, Guo Z, Zhang Y. A versatile contribution of both aminopeptidases N and ABC transporters to Bt Cry1Ac toxicity in the diamondback moth. BMC Biol 2022; 20:33. [PMID: 35120513 PMCID: PMC8817492 DOI: 10.1186/s12915-022-01226-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 01/04/2022] [Indexed: 02/22/2023] Open
Abstract
BACKGROUND Biopesticides and transgenic crops based on Bacillus thuringiensis (Bt) toxins are extensively used to control insect pests, but the rapid evolution of insect resistance seriously threatens their effectiveness. Bt resistance is often polygenic and complex. Mutations that confer resistance occur in midgut proteins that act as cell surface receptors for the toxin, and it is thought they facilitate its assembly as a membrane-damaging pore. However, the mechanistic details of the action of Bt toxins remain controversial. RESULTS We have examined the contribution of two paralogous ABC transporters and two aminopeptidases N to Bt Cry1Ac toxicity in the diamondback moth, Plutella xylostella, using CRISPR/Cas9 to generate a series of homozygous polygenic knockout strains. A double-gene knockout strain, in which the two paralogous ABC transporters ABCC2 and ABCC3 were deleted, exhibited 4482-fold resistance to Cry1A toxin, significantly greater than that previously reported for single-gene knockouts and confirming the mutual functional redundancy of these ABC transporters in acting as toxin receptors in P. xylostella. A double-gene knockout strain in which APN1 and APN3a were deleted exhibited 1425-fold resistance to Cry1Ac toxin, providing the most direct evidence to date for these APN proteins acting as Cry1Ac toxin receptors, while also indicating their functional redundancy. Genetic crosses of the two double-gene knockouts yielded a hybrid strain in which all four receptor genes were deleted and this resulted in a > 34,000-fold resistance, indicating that while both types of receptor need to be present for the toxin to be fully effective, there is a level of functional redundancy between them. The highly resistant quadruple knockout strain was less fit than wild-type moths, but no fitness cost was detected in the double knockout strains. CONCLUSION Our results provide direct evidence that APN1 and APN3a are important for Cry1Ac toxicity. They support our overarching hypothesis of a versatile mode of action of Bt toxins, which can compensate for the absence of individual receptors, and are consistent with an interplay among diverse midgut receptors in the toxins' mechanism of action in a super pest.
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Affiliation(s)
- Dan Sun
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong, 510642, China
| | - Liuhong Zhu
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Le Guo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Shaoli Wang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Qingjun Wu
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Neil Crickmore
- School of Life Sciences, University of Sussex, Brighton, BN1 9QE, UK
| | - Xuguo Zhou
- Department of Entomology, University of Kentucky, Lexington, KY, 40546-0091, USA
| | - Alejandra Bravo
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, 62250, Morelos, México
| | - Mario Soberón
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, 62250, Morelos, México
| | - Zhaojiang Guo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Youjun Zhang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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Wang Y, Adegawa S, Miyamoto K, Takasu Y, Iizuka T, Wada S, Mang D, Li X, Kim S, Sato R, Watanabe K. ATP-binding cassette transporter subfamily C members 2, 3 and cadherin protein are susceptibility-determining factors in Bombyx mori for multiple Bacillus thuringiensis Cry1 toxins. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 139:103649. [PMID: 34560243 DOI: 10.1016/j.ibmb.2021.103649] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/13/2021] [Accepted: 09/13/2021] [Indexed: 06/13/2023]
Abstract
Field-evolved resistance of insect pests to Bacillus thuringiensis (Bt) toxins (Cry toxins) is a threat to the efficacy of Bt-based bio-insecticides and transgenic crops. Recent reports have suggested that ATP-binding cassette transporter subfamily C2 (ABCC2) and cadherin-like receptor play important roles in conferring susceptibility to Cry1 toxins. However, the receptors involved in Bt susceptibility in each insect remain unclear. To determine the receptors that are involved in the susceptibility of Bombyx mori to Cry1 toxins (1Ab, 1Ac and 1Fa), we conducted diet overlay bioassay using B. mori strains disrupted with one or two receptor (s) among BmABCC2, BmABCC3, and cadherin-like receptor (BtR175) generated by transcription activator-like effector nuclease (TALEN)-mediated gene editing. The single-knockout strains for BmABCC2 showed resistance to Cry1Ab and Cry1Ac, whereas only strains with double knockout of BmABCC2 and BmABCC3 exhibited high resistance to Cry1Fa. Progeny populations generated from the crossing of heterozygotes for BtR175 knockout allele included 25% theoretical homozygotes for the BtR175 knockout allele and they showed resistance to Cry1Ab and Cry1Ac. Then, through a cell swelling assay using Sf9 cells ectopically expressing the receptor, we analyzed the mechanisms underlying the different contributions of BmABCC2, BmABCC3, and BtR175 to larval susceptibility. The receptor activity of BmABCC2 for Cry1Ab and Cry1Ac was far higher than that of BmABCC3, and BtR175 synergistically enhanced the receptor activity of BmABCC2. This result well explained the important involvement of BmABCC2 and BtR175 in the larval susceptibility to Cry1A toxins. By contrast, the receptor activities of BmABCC2 and BmABCC3 for Cry1Fa were observed at a similar level and synergistic effect of BtR175 was small. This finding explains the equal importance of BmABCC2 and BmABCC3 and very small contribution of BtR175 on larval susceptibility to Cry1Fa. Thus, we demonstrated the different importance of BmABCC2, BmABCC3, and BtR175 to various Cry1 toxins as susceptibility-determining factors in B. mori larvae and the underlying basis for the observed differences. Furthermore, a weak correlation was indicated between the binding affinity and receptor activities of BmABCC2 and BmABCC3 to Cry1 toxins.
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Affiliation(s)
- Yonghao Wang
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Satomi Adegawa
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Kazuhisa Miyamoto
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan
| | - Yoko Takasu
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan
| | - Tetsuya Iizuka
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan
| | - Sanae Wada
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan
| | - Dingze Mang
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Xiaoyi Li
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Seungwon Kim
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan.
| | - Kenji Watanabe
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan.
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9
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Adegawa S, Yamaguchi N, Sato R. The base and root of domain II loops of Cry toxins contribute to binding to Bombyx mori ABC transporter C2. FEBS J 2021; 289:965-984. [PMID: 34618400 DOI: 10.1111/febs.16224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 08/28/2021] [Accepted: 10/06/2021] [Indexed: 01/17/2023]
Abstract
Little information is available regarding the region of Cry toxins involved in binding to their major receptors, the ATP-binding cassette (ABC) transporters. We analyzed which Cry1Aa amino acid residues contribute to binding to Bombyx mori ABC transporter C2 (BmABCC2). Several two oxidized double-cysteine substitution mutant toxins were made. In these, two amino acids at distant positions on toxin loop α8 and loop 2 or loop 2 and loop 3 were substituted with cysteine residues and crosslinked. These mutants exhibited a marked reduction in binding affinity to BmABCC2, suggesting that the binding site comprises complex cavities formed by loops α8, 2, and 3. Loop swapping between Cry1Aa and other BmABCC2-incompatible toxins indicated that loop 2 acts as a binding affinity-generating part of Cry1Aa toxin. Using single amino acid substitution mutants, the results of surface plasmon resonance (SPR) analysis and response assays with BmABCC2-expressing Sf9 cells indicated that Y366, R367, R368, and L447 in the Cry1Aa root and base region of loops 2 and 3 play important roles in binding. Furthermore, SPR analyses of these mutants suggested that a two-state binding model fits best the data obtained. Moreover, complex cavities and the above-mentioned amino acid residues contribute to the generation of multiple binding points and high-affinity binding. Finally, we found that the binding site of B. mori cadherin-like protein consists of complex cavities comprising loops 1, 2, and 3, partially overlapping that of BmABCC2, suggesting that the loop region of Cry1Aa toxin acts as a promiscuous binding site.
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Affiliation(s)
- Satomi Adegawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Japan.,Japan Society for the Promotion of Science Research Fellowship for Young Scientists, Chiyoda, Japan
| | - Naomi Yamaguchi
- Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Japan
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10
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Güney G, Cedden D, Hänniger S, Heckel DG, Coutu C, Hegedus DD, Mutlu DA, Suludere Z, Sezen K, Güney E, Toprak U. Silencing of an ABC transporter, but not a cadherin, decreases the susceptibility of Colorado potato beetle larvae to Bacillus thuringiensis ssp. tenebrionis Cry3Aa toxin. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2021; 108:e21834. [PMID: 34288075 DOI: 10.1002/arch.21834] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/24/2021] [Accepted: 07/02/2021] [Indexed: 06/13/2023]
Abstract
The Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae), is a major pest of potato plants worldwide and is notorious for its ability to develop resistance to insecticides. Cry3 toxins synthesized by Bacillus thuringiensis ssp. tenebrionis have been used successfully to manage this pest. Resistance to Cry toxins is a concerning problem for many insect pests; therefore, it is important to determine the mechanisms by which insects acquire resistance to these toxins. Cadherin-like and ABC transporter proteins have been implicated in the mode of action of Cry toxins as mutations in these genes render lepidopterans resistant to them; however, clear consensus does not exist on whether these proteins also play a role in Cry3 toxin activity and/or development of resistance in coleopterans. In the current study, we identified the L. decemlineata orthologues of the cadherin (LdCAD) and the ABCB transporter (LdABCB1) that have been implicated in the mode of action of Cry toxins in other coleopterans. Suppression of LdABCB1 via RNA interference reduced toxin-related larval mortality, whereas partial silencing of LdCAD did not. Our results suggest that the ABCB is involved in the mode of action of Cry3Aa toxins; however, no evidence was found to support the role of cadherin as a receptor of Cry3Aa in L. decemlineata.
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Affiliation(s)
- Gözde Güney
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
- Max Planck Institute for Chemical Ecology, Jena, Germany
- Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada
| | - Doğa Cedden
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
| | | | - David G Heckel
- Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Cathy Coutu
- Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada
| | - Dwayne D Hegedus
- Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | | | - Kazım Sezen
- Department of Biology, Karadeniz Technical University, Trabzon, Turkey
| | - Ebru Güney
- Department of Biology, Karadeniz Technical University, Trabzon, Turkey
| | - Umut Toprak
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
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11
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Hao X, Wang B, Chen J, Wang B, Xu J, Pan J, Ma L. Molecular characterization and functional analysis of multidrug resistance-associated genes of Pinewood nematode (Bursaphelenchus xylophilus) for nematicides. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2021; 177:104902. [PMID: 34301363 DOI: 10.1016/j.pestbp.2021.104902] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 05/10/2021] [Accepted: 06/09/2021] [Indexed: 05/02/2023]
Abstract
Bursaphelenchus xylophilus (Pinewood nematode, PWN) is the causative agent of pine wilt disease (PWD) which caused serious threat to pine forests in the world, especially in East Asia and Western Europe. At present, the control of PWD mainly rely on the massive use of pesticide despite the damage to human health and environmental safety. Developing novel drug targets is the optimized strategy for developing new method to control PWN. In this study, four multidrug resistance-associated protein (MRP) genes containing highly conserved MRP-associated domains were cloned from PWN. The expression patterns of the four Bx-mrps under three different nematicides treatments were studied by quantitative reverse transcription PCR (qRT-PCR) and the function of the four genes in multidrug resistance were also validated by RNA interference (RNAi). Results showed that the expression of Bx-mrp1, Bx-mrp2, Bx-mrp3, and Bx-mrp4 were significantly increased when exposed to different nematicides, wherein, Bx-mrp4 exposed by 4.0 mg/mL of matrine own the highest expression level. The mortality rates of Bx-mrps silenced nematodes revealed significant increase(P < 0.05)under matrine, avermectin, and emamectin benzoate exposure. Specially, Bx-mrp4 exposed with 4.0 mg/mL matrine for 24 h own the highest mortality increase by 18.34%. After RNAi of Bx-mrps, feeding ability of the nematodes were also significantly decreased. These results demonstrate that Bx-mrps were linked to the detoxification process and feeding behavior of PWN. Silencing of Bx-mrps can lead to increased sensitivity of PWN to nematicides and decrease its feeding ability. Bx-mrps are potential new PWN control targets in the future.
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Affiliation(s)
- Xin Hao
- School of Forestry, Northeast Forestry University, Harbin 150040, China.
| | - Bowen Wang
- School of Forestry, Northeast Forestry University, Harbin 150040, China
| | - Jie Chen
- School of Forestry, Northeast Forestry University, Harbin 150040, China
| | - Buyong Wang
- School of Agriculture and Bioengineering, Heze University, Heze 274015, China
| | - Jiayao Xu
- School of Forestry, Northeast Forestry University, Harbin 150040, China
| | - Jialiang Pan
- Key laboratory of State Forestry Administration on Forest Pest Monitoring and Warning, General Station of Forest and Grassland Pest Management, General Station of Forest and Grassland Pest Management, National Forestry and Grassland Administration, Shenyang 110034, China..
| | - Ling Ma
- School of Forestry, Northeast Forestry University, Harbin 150040, China.
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12
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Liu Y, Jin M, Wang L, Wang H, Xia Z, Yang Y, Bravo A, Soberón M, Xiao Y, Liu K. SfABCC2 transporter extracellular loops 2 and 4 are responsible for the Cry1Fa insecticidal specificity against Spodoptera frugiperda. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 135:103608. [PMID: 34119653 DOI: 10.1016/j.ibmb.2021.103608] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/28/2021] [Accepted: 06/06/2021] [Indexed: 06/12/2023]
Abstract
Bacillus thuringiensis (Bt) bacteria produce Cry toxins that kill insect pests. Insect specificity of Cry toxins relies on their binding to larval gut membrane proteins such as cadherin and ATP-binding cassette (ABC) transporter proteins. Mutations in ABC transporters have been implicated in high levels of resistance to Cry toxins in multiple pests. Spodoptera frugiperda is an insect pest susceptible to Cry1Fa and Cry1Ab toxins while Mythimna separata is tolerant to Cry1Fa and less susceptible to Cry1Ab. Here, we analyzed the potential role of ABCC2 in determining the susceptibility of S. frugiperda to Cry1Fa and Cry1Ab, by expressing SfABCC2 or MsABCC2 in Hi5 insect cell line and by the systematic replacements of extracellular loops (ECLs) between these two proteins. Expression of SfABCC2 in Hi5 conferred susceptibility to both Cry1Fa and Cry1Ab, in contrast to the expression of MsABCC2 that mediated low toxicity to Cry1Ab and no toxicity to Cry1Fa in agreement with their larvicidal toxicities. The SfABCC2 and MsABCC2 amino acid sequences showed differential residues among ECL1, ECL2, ECL4 and ECL6 loops, while ECL3 and ECL5 share the same primary sequence. The exchange of ECLs between SfABCC2 and MsABCC2 demonstrated that ECL4 and ECL2 contribute to Cry1Fa toxicity, where ECL4 plays a major role. The medium region (named M2) of ECL4 was identified as the most important region of SfABCC2 involved in Cry1Fa toxicity as shown by point mutations in this region. These findings will be helpful to understand the mechanisms of action of Bt toxins in S. frugiperda.
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Affiliation(s)
- Yuanyuan Liu
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China
| | - Minghui Jin
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Ling Wang
- Key Laboratory of Integrated Pest Management on Crops in Central China, Ministry of Agriculture, Hubei Key Laboratory of Crop Disease, Insect Pests and Weeds Control, Institute of Plant Protection and Soil Fertility, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China
| | - Haixia Wang
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China
| | - Zhichao Xia
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China
| | - Yongbo Yang
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China
| | - Alejandra Bravo
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, 62250, Morelos, Mexico
| | - Mario Soberón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, 62250, Morelos, Mexico
| | - Yutao Xiao
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China.
| | - Kaiyu Liu
- Institute of Entomology, School of Life Sciences, Central China Normal University, Wuhan, 430079, PR China.
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13
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The Essential and Enigmatic Role of ABC Transporters in Bt Resistance of Noctuids and Other Insect Pests of Agriculture. INSECTS 2021; 12:insects12050389. [PMID: 33924857 PMCID: PMC8145640 DOI: 10.3390/insects12050389] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 04/25/2021] [Accepted: 04/26/2021] [Indexed: 11/18/2022]
Abstract
Simple Summary The insect family, Noctuidae, contains some of the most damaging pests of agriculture, including bollworms, budworms, and armyworms. Transgenic cotton and maize expressing Cry-type insecticidal proteins from Bacillus thuringiensis (Bt) are protected from such pests and greatly reduce the need for chemical insecticides. However, evolution of Bt resistance in the insects threatens the sustainability of this environmentally beneficial pest control strategy. Understanding the interaction between Bt toxins and their targets in the insect midgut is necessary to evaluate the risk of resistance evolution. ABC transporters, which in eukaryotes typically expel small molecules from cells, have recently been proposed as a target for the pore-forming Cry toxins. Here we review the literature surrounding this hypothesis in noctuids and other insects. Appreciation of the critical role of ABC transporters will be useful in discovering counterstrategies to resistance, which is already evolving in some field populations of noctuids and other insects. Abstract In the last ten years, ABC transporters have emerged as unexpected yet significant contributors to pest resistance to insecticidal pore-forming proteins from Bacillus thuringiensis (Bt). Evidence includes the presence of mutations in resistant insects, heterologous expression to probe interactions with the three-domain Cry toxins, and CRISPR/Cas9 knockouts. Yet the mechanisms by which ABC transporters facilitate pore formation remain obscure. The three major classes of Cry toxins used in agriculture have been found to target the three major classes of ABC transporters, which requires a mechanistic explanation. Many other families of bacterial pore-forming toxins exhibit conformational changes in their mode of action, which are not yet described for the Cry toxins. Three-dimensional structures of the relevant ABC transporters, the multimeric pore in the membrane, and other proteins that assist in the process are required to test the hypothesis that the ATP-switch mechanism provides a motive force that drives Cry toxins into the membrane. Knowledge of the mechanism of pore insertion will be required to combat the resistance that is now evolving in field populations of insects, including noctuids.
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14
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Pinaud S, Tetreau G, Poteaux P, Galinier R, Chaparro C, Lassalle D, Portet A, Simphor E, Gourbal B, Duval D. New Insights Into Biomphalysin Gene Family Diversification in the Vector Snail Biomphalaria glabrata. Front Immunol 2021; 12:635131. [PMID: 33868258 PMCID: PMC8047071 DOI: 10.3389/fimmu.2021.635131] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 03/08/2021] [Indexed: 11/30/2022] Open
Abstract
Aerolysins initially characterized as virulence factors in bacteria are increasingly found in massive genome and transcriptome sequencing data from metazoans. Horizontal gene transfer has been demonstrated as the main way of aerolysin-related toxins acquisition in metazoans. However, only few studies have focused on their potential biological functions in such organisms. Herein, we present an extensive characterization of a multigene family encoding aerolysins - named biomphalysin - in Biomphalaria glabrata snail, the intermediate host of the trematode Schistosoma mansoni. Our results highlight that duplication and domestication of an acquired bacterial toxin gene in the snail genome result in the acquisition of a novel and diversified toxin family. Twenty-three biomphalysin genes were identified. All are expressed and exhibited a tissue-specific expression pattern. An in silico structural analysis was performed to highlight the central role played by two distinct domains i) a large lobe involved in the lytic function of these snail toxins which constrained their evolution and ii) a small lobe which is structurally variable between biomphalysin toxins and that matched to various functional domains involved in moiety recognition of targets cells. A functional approach suggests that the repertoire of biomphalysins that bind to pathogens, depends on the type of pathogen encountered. These results underline a neo-and sub-functionalization of the biomphalysin toxins, which have the potential to increase the range of effectors in the snail’s immune arsenal.
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Affiliation(s)
- Silvain Pinaud
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - Guillaume Tetreau
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - Pierre Poteaux
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - Richard Galinier
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - Cristian Chaparro
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - Damien Lassalle
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - Anaïs Portet
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - Elodie Simphor
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - Benjamin Gourbal
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
| | - David Duval
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via Domitia, Perpignan, France.,CNRS, IFREMER, University of Montpellier, Perpignan, France
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15
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Resistance to Bacillus thuringiensis Cry1Ac toxin requires mutations in two Plutella xylostella ATP-binding cassette transporter paralogs. PLoS Pathog 2020; 16:e1008697. [PMID: 32776976 PMCID: PMC7446926 DOI: 10.1371/journal.ppat.1008697] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 08/20/2020] [Accepted: 06/09/2020] [Indexed: 12/27/2022] Open
Abstract
The diamondback moth, Plutella xylostella, is a cosmopolitan pest and the first species to develop field resistance to toxins from the gram-positive bacterium Bacillus thuringiensis (Bt). Although previous work has suggested that mutations of ATP-binding cassette transporter subfamily C2 (ABCC2) or C3 (ABCC3) genes can confer Cry1Ac resistance, here we reveal that P. xylostella requires combined mutations in both PxABCC2 and PxABCC3 to achieve high-level Cry1Ac resistance, rather than simply a mutation of either gene. We identified natural mutations of PxABCC2 and PxABCC3 that concurrently occurred in a Cry1Ac-resistant strain (Cry1S1000) of P. xylostella, with a mutation (RA2) causing the mis-splicing of PxABCC2 and another mutation (RA3) leading to the premature termination of PxABCC3. Genetic linkage analysis showed that RA2 and RA3 were tightly linked to Cry1Ac resistance. Introgression of RA2 and RA3 enabled a susceptible strain (G88) of P. xylostella to obtain high resistance to Cry1Ac, confirming that these genes confer resistance. To further support the role of PxABCC2 and PxABCC3 in Cry1Ac resistance, frameshift mutations were introduced into PxABCC2 and PxABCC3 singly and in combination in the G88 strain with CRISPR/Cas9 mediated mutagenesis. Bioassays of CRISPR-based mutant strains, plus genetic complementation tests, demonstrated that the deletion of PxABCC2 or PxABCC3 alone provided < 4-fold tolerance to Cry1Ac, while disruption of both genes together conferred >8,000-fold resistance to Cry1Ac, suggesting the redundant/complementary roles of PxABCC2 and PxABCC3. This work advances our understanding of Bt resistance in P. xylostella by demonstrating mutations within both PxABCC2 and PxABCC3 genes are required for high-level Cry1Ac resistance. Bacillus thuringiensis (Bt) foliar sprays and transgenic crops expressing Bt toxins are used extensively to control insect pests, but the evolution of resistance limits their efficacy. Multiple studies have reported that ATP-binding cassette (ABC) transporters are important Bt receptors, and mutations in either ABCC2 or ABCC3 can lead to Cry1Ac-toxin resistance, although this process is not fully understood. In this study, we applied both forward and reverse genetic analyses to demonstrate that high-level Bt-Cry1Ac resistance in Plutella xylostella requires concurrent mutations in both PxABCC2 and PxABCC3. We identified inactivating mutations in these two genes from a Cry1Ac-resistant strain (Cry1S1000) of P. xylostella and conducted genetic linkage analysis, which supported the role that PxABCC2 and PxABCC3 were the causal genes of Cry1Ac resistance. We then knocked out PxABCC2 and PxABCC3 in a P. xylostella susceptible reference strain (G88) to confirm that high-level Cry1Ac resistance requires mutation of PxABCC2 and PxABCC3, rather than a mutation of either one gene. This finding expands our understanding of complex Bt resistance processes and may be relevant to Bt-Cry1Ac resistance in other lepidopteran insects.
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16
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Huang J, Xu Y, Zuo Y, Yang Y, Tabashnik BE, Wu Y. Evaluation of five candidate receptors for three Bt toxins in the beet armyworm using CRISPR-mediated gene knockouts. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 121:103361. [PMID: 32199887 DOI: 10.1016/j.ibmb.2020.103361] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/06/2020] [Accepted: 03/15/2020] [Indexed: 05/29/2023]
Abstract
Insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) can provide safe and effective control of some major pests, but evolution of resistance by pests diminishes these benefits. Better understanding of the genetics and mechanisms of resistance is urgently needed to improve methods for monitoring, managing, and countering pest resistance to Bt toxins. Here we used CRISPR-mediated knockouts to evaluate the role of five genes encoding candidate Bt toxin receptors in Spodoptera exigua (beet armyworm), a devastating pest of vegetable, field and flower crops. We compared susceptibility to Bt toxins Cry1Ac, Cry1Fa, and Cry1Ca between the parent susceptible strain and each of five strains homozygous for the knockout of one of the candidate genes (SeAPN1, SeCad1, SeABCC1, SeABCC2 or SeABCC3). The results from the 15 pairwise comparisons reveal that SeABCC2 has a major role and SeCad1 a minor role in mediating toxicity of Cry1Ac and Cry1Fa. SeABCC2 also has a minor role in toxicity of Cry1Ca. In addition, the results imply little or no role for the other three candidate receptors in toxicity of Cry1Ac or Cry1Fa; or for the four candidate receptors other than SeABCC2 in toxicity of Cry1Ca.
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Affiliation(s)
- Jianlei Huang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Yanjun Xu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Yayun Zuo
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Yihua Yang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Bruce E Tabashnik
- Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA.
| | - Yidong Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
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17
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Ren X, Wang Y, Ma Y, Jiang W, Ma X, Hu H, Wang D, Ma Y. Midgut de novo transcriptome analysis and gene expression profiling of Spodoptera exigua larvae exposed with sublethal concentrations of Cry1Ca protein. 3 Biotech 2020; 10:138. [PMID: 32158634 DOI: 10.1007/s13205-020-2129-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 02/11/2020] [Indexed: 12/01/2022] Open
Abstract
Spodoptera exigua (Hübner) is a polyphagous pest on agricultural crops, whose control is based mainly on the application of chemical insecticides. Bacillus thuringiensis (Bt) is one of the most important biological agents that have been successfully applied as a biological control, and Cry1Ca protein is considered to be active against S. exigua. Therefore, to understand the response of S. exigua to Cry1Ca protein, high-throughput sequencing was used to analyse the S. exigua larval midgut after treatment with sublethal concentrations of Cry1Ca protein. Transcriptome data showed that a total of 98,571 unigenes with an N50 value of 1135 bp and a mean length of 653 bp were obtained. Furthermore, 2962 differentially expressed genes (DEGs) were identified after Cry1Ca challenge, including 1508 up-regulated and 1454 down-regulated unigenes. Among these DEGs, detoxification (CYP, CarE, and GST) and Bt resistance (ALP, APN, and ABC transporter)-related genes were differentially expressed in the midgut of S. exigua after Cry1Ca treatment. However, most DEGs of protective enzymes were down-regulated, while most DEGs related with serine protease and REPAT were up-regulated. Furthermore, almost all DEGs related to the immune signaling pathway, antimicrobial protein, and lysozyme were up-regulated by Cry1Ca treatment. These results indicated that the detoxification enzyme, protective enzymes, Bt resistance-related genes, serine protease, REPAT, and the immune response might have been involved in the response of S. exigua to Cry1Ca protein. In summary, analysis of the transcriptomal expression of genes involved in Cry1Ca protein against S. exigua provided potential clues for elucidating the host response processes and defensive mechanisms underlying Cry1Ca toxicity.
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Affiliation(s)
- Xiangliang Ren
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Yingying Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
- Honghu Agricultural Technology Extension Center, Jingzhou, 433200 Hubei China
| | - Yajie Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Weili Jiang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Xiaoyan Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Hongyan Hu
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Dan Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
| | - Yan Ma
- State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000 Henan China
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18
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Li X, Miyamoto K, Takasu Y, Wada S, Iizuka T, Adegawa S, Sato R, Watanabe K. ATP-Binding Cassette Subfamily A Member 2 is a Functional Receptor for Bacillus thuringiensis Cry2A Toxins in Bombyx mori, but not for Cry1A, Cry1C, Cry1D, Cry1F, or Cry9A Toxins. Toxins (Basel) 2020; 12:E104. [PMID: 32041133 PMCID: PMC7076765 DOI: 10.3390/toxins12020104] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 11/29/2022] Open
Abstract
: Cry toxins are insecticidal proteins produced by Bacillus thuringiensis (Bt). They are used commercially to control insect pests since they are very active in specific insects and are harmless to the environment and human health. The gene encoding ATP-binding cassette subfamily A member 2 (ABCA2) was identified in an analysis of Cry2A toxin resistance genes. However, we do not have direct evidence for the role of ABCA2 for Cry2A toxins or why Cry2A toxin resistance does not cross to other Cry toxins. Therefore, we performed two experiments. First, we edited the ABCA2 sequence in Bombyx mori using transcription activator-like effector-nucleases (TALENs) and confirmed the susceptibility-determining ability in a diet overlay bioassay. Strains with C-terminal half-deleted BmABCA2 showed strong and specific resistance to Cry2A toxins; even strains carrying a deletion of 1 to 3 amino acids showed resistance. However, the C-terminal half-deleted strains did not show cross-resistance to other toxins. Second, we conducted a cell swelling assay and confirmed the specific ability of BmABCA2 to Cry2A toxins in HEK239 cells. Those demonstrated that BmABCA2 is a functional receptor for Cry2A toxins and that BmABCA2 deficiency-dependent Cry2A resistance does not confer cross-resistance to Cry1A, Cry1F, Cry1Ca, Cry1Da, or Cry9Aa toxins.
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Affiliation(s)
- Xiaoyi Li
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Kazuhisa Miyamoto
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Yoko Takasu
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Sanae Wada
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Tetsuya Iizuka
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
| | - Satomi Adegawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan; (X.L.); (S.A.)
| | - Kenji Watanabe
- Institute of Agrobiological Sciences, NARO, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan; (K.M.); (Y.T.); (S.W.); (T.I.)
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19
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Breeschoten T, Ros VID, Schranz ME, Simon S. An influential meal: host plant dependent transcriptional variation in the beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae). BMC Genomics 2019; 20:845. [PMID: 31722664 PMCID: PMC6854893 DOI: 10.1186/s12864-019-6081-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/05/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND To understand the genetic mechanisms of insect herbivory, the transcriptional response of insects feeding on different host plant species has to be studied. Here, we generated gene expression data of the generalist herbivore Spodoptera exigua (Hübner) feeding on three selected host plant species and a control (artificial diet). The host plant species used in this study -cabbage (Brassica oleracea), maize (Zea mays) and tobacco (Nicotiana tabacum)- are members of different plant families that each employ specific defence mechanisms and toxins. RESULTS Spodoptera exigua larvae had a higher growth rate, indicator for herbivore success, when feeding on Z. mays compared to larvae feeding on B. oleracea or N. tabacum. Larvae feeding on the different host plant species showed divergent transcriptional responses. We identified shared and unique gene expression patterns dependent of the host plant species the larvae fed on. Unique gene expression patterns, containing uniquely upregulated transcripts including specific detoxification genes, were found for larvae feeding on either B. oleracea or N. tabacum. No diet-specific gene cluster was identified for larvae feeding on the host for which larvae showed optimal herbivore success, Z. mays, or artificial diet. In contrast, for larvae feeding on hosts for which they showed low herbivore success, specific diet-dependent gene clusters were identified. Functional annotation of these clusters indicates that S. exigua larvae deploy particular host plant-specific genes for digestion and detoxification. CONCLUSIONS The lack of a host plant-specific gene activity for larvae feeding on Z. mays and the artificial diet suggest a general and non-specific gene activity for host plants with optimal herbivore success. Whereas the finding of specific gene clusters containing particular digestion and detoxifying genes expressed in larvae feeding on B. oleracea and N. tabacum, with low herbivore success, imply a host plant-specific gene activity for larvae feeding on host plants with suboptimal herbivore success. This observation leads to the conclusion that a polyphagous herbivore is able to feed on a large variation of host plants due to the flexibility and diversity of genes involved in digestion and detoxification that are deployed in response to particular host plant species.
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Affiliation(s)
- Thijmen Breeschoten
- Biosystematics Group, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
| | - Vera I D Ros
- Laboratory of Virology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - M Eric Schranz
- Biosystematics Group, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - Sabrina Simon
- Biosystematics Group, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
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Guo Z, Sun D, Kang S, Zhou J, Gong L, Qin J, Guo L, Zhu L, Bai Y, Luo L, Zhang Y. CRISPR/Cas9-mediated knockout of both the PxABCC2 and PxABCC3 genes confers high-level resistance to Bacillus thuringiensis Cry1Ac toxin in the diamondback moth, Plutella xylostella (L.). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 107:31-38. [PMID: 30710623 DOI: 10.1016/j.ibmb.2019.01.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 12/18/2018] [Accepted: 01/29/2019] [Indexed: 05/20/2023]
Abstract
Rapid evolution of resistance by insect pests severely jeopardizes the sustainable utilization of biopesticides and transgenic crops that produce insecticidal crystal proteins derived from the entomopathogenic bacterium Bacillus thuringiensis (Bt). Recently, high levels of resistance to Bt Cry1 toxins have been reported to be genetically linked to the mutation or down-regulation of ABC transporter subfamily C genes ABCC2 and ABCC3 in seven lepidopteran insects, including Plutella xylostella (L.). To further determine the causal relationship between alterations in the PxABCC2 and PxABCC3 genes and Cry1Ac resistance in P. xylostella, the novel CRISPR/Cas9 genome engineering system was utilized to successfully construct two knockout strains: the ABCC2KO strain is homozygous for a 4-bp deletion in exon 3 of the PxABCC2 gene, and the ABCC3KO strain is homozygous for a 5-bp deletion in exon 3 of the PxABCC3 gene, both of which can produce only truncated ABCC proteins. Bioassay results indicated that high levels of resistance to the Cry1Ac protoxin were observed in both the ABCC2KO (724-fold) and ABCC3KO (413-fold) strains compared to the original susceptible DBM1Ac-S strain. Subsequently, dominance degree and genetic complementation tests demonstrated that Cry1Ac resistance in both the knockout strains was incompletely recessive, and Cry1Ac resistance alleles were located in the classic BtR-1 resistance locus that harbored the PxABCC2 and PxABCC3 genes, similar to the near-isogenic resistant NIL-R strain. Moreover, qualitative toxin binding assays revealed that the binding of the Cry1Ac toxin to midgut brush border membrane vesicles (BBMVs) in both knockout strains was dramatically reduced compared to that in the susceptible DBM1Ac-S strain. In summary, our CRISPR/Cas9-mediated genome editing study presents, for the first time, in vivo reverse genetics evidence for both the ABCC2 and ABCC3 proteins as midgut functional receptors for Bt Cry1 toxins in insects, which provides new insight into the pivotal roles of both the ABCC2 and ABCC3 proteins in the complex molecular mechanism of insect resistance to Bt Cry1 toxins.
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Affiliation(s)
- Zhaojiang Guo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Dan Sun
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Shi Kang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Junlei Zhou
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Lijun Gong
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Jianying Qin
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Le Guo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Liuhong Zhu
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Yang Bai
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Liang Luo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Youjun Zhang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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21
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Pinos D, Martínez-Solís M, Herrero S, Ferré J, Hernández-Martínez P. The Spodoptera exigua ABCC2 Acts as a Cry1A Receptor Independently of its Nucleotide Binding Domain II. Toxins (Basel) 2019; 11:toxins11030172. [PMID: 30909393 PMCID: PMC6468857 DOI: 10.3390/toxins11030172] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/18/2019] [Accepted: 03/20/2019] [Indexed: 12/27/2022] Open
Abstract
ABC proteins are primary-active transporters that require the binding and hydrolysis of ATP to transport substrates across the membrane. Since the first report of an ABCC2 transporter as receptor of Cry1A toxins, the number of ABC transporters known to be involved in the mode of action of Cry toxins has increased. In Spodoptera exigua, a mutation in the SeABCC2 gene is described as genetically linked to resistance to the Bt-product XentariTM. This mutation affects an intracellular domain involved in ATP binding, but not the extracellular loops. We analyzed whether this mutation affects the role of the SeABCC2 as a functional receptor to Cry1A toxins. The results show that Sf21 cells expressing the truncated form of the transporter were susceptible to Cry1A toxins. Moreover, specific Cry1Ac binding was observed in those cells expressing the truncated SeABCC2. Additionally, no differences in the irreversible Cry1Ac binding component (associated with the toxin insertion into the membrane) were observed when tested in Sf21 cells expressing either the full-length or the truncated form of the SeABCC2 transporter. Therefore, our results point out that the partial lack of the nucleotide binding domain II in the truncated transporter does not affect its functionality as a Cry1A receptor.
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Affiliation(s)
- Daniel Pinos
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
| | - María Martínez-Solís
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
| | - Salvador Herrero
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
| | - Juan Ferré
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
| | - Patricia Hernández-Martínez
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
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22
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Abdelgaffar H, Tague ED, Castro Gonzalez HF, Campagna SR, Jurat-Fuentes JL. Midgut metabolomic profiling of fall armyworm (Spodoptera frugiperda) with field-evolved resistance to Cry1F corn. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 106:1-9. [PMID: 30630033 DOI: 10.1016/j.ibmb.2019.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 12/21/2018] [Accepted: 01/05/2019] [Indexed: 06/09/2023]
Abstract
Populations of the fall armyworm (Spodoptera frugiperda) have developed resistance to transgenic corn producing the Cry1F insecticidal protein from the bacterium Bacillus thuringiensis (Bt). Resistance in S. frugiperda from Puerto Rico is genetically linked to a mutation in an ATP Binding Cassette subfamily C2 gene (SfABCC2) that results in a truncated, non-functional Cry1F toxin receptor protein. Since ABCC2 proteins are involved in active export of xenobiotics and other metabolites from the cell, we hypothesized that Cry1F-resistant fall armyworm with a non-functional SfABCC2 protein would display altered gut metabolome composition when compared to susceptible insects. Mass spectrometry and multivariate statistical analyses identified 126 unique metabolites from larval guts, of which 7 were found to display statistically significant altered levels between midguts from susceptible and Cry1F-resistant S. frugiperda larvae when feeding on meridic diet. Among these 7 differentially present metabolites, 6 were found to significantly accumulate (1.3-3.5-fold) in midguts from Cry1F-resistant larvae, including nucleosides, asparagine, and carbohydrates such as trehalose 6-phosphate and sedoheptulose 1/7-phosphate. In contrast, metabolomic comparisons of larvae fed on non-transgenic corn identified 5 metabolites with statistically significant altered levels and only 2 of them, 2-isopropylmalate and 3-phosphoserine, that significantly accumulated (2.3- and 3.5-fold, respectively) in midguts from Cry1F-resistant compared to susceptible larvae. These results identify a short list of candidate metabolites that may be transported by SfABCC2 and that may have the potential to be used as resistance markers.
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Affiliation(s)
- Heba Abdelgaffar
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, 37996, USA
| | - Eric D Tague
- Department of Chemistry, University of Tennessee, Knoxville, 37996, USA
| | - Hector F Castro Gonzalez
- Department of Chemistry, University of Tennessee, Knoxville, 37996, USA; Biological and Small Molecule Mass Spectrometry Core, University of Tennessee, Knoxville, 37996, USA
| | - Shawn R Campagna
- Department of Chemistry, University of Tennessee, Knoxville, 37996, USA; Biological and Small Molecule Mass Spectrometry Core, University of Tennessee, Knoxville, 37996, USA
| | - Juan L Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, 37996, USA.
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23
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Sato R, Adegawa S, Li X, Tanaka S, Endo H. Function and Role of ATP-Binding Cassette Transporters as Receptors for 3D-Cry Toxins. Toxins (Basel) 2019; 11:E124. [PMID: 30791434 PMCID: PMC6409751 DOI: 10.3390/toxins11020124] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/13/2019] [Accepted: 02/15/2019] [Indexed: 12/20/2022] Open
Abstract
When ABC transporter family C2 (ABCC2) and ABC transporter family B1 (ABCB1) were heterologously expressed in non-susceptible cultured cells, the cells swelled in response to Cry1A and Cry3 toxins, respectively. Consistent with the notion that 3D-Cry toxins form cation-permeable pores, Bombyx mori ABCC2 (BmABCC2) facilitated cation-permeable pore formation by Cry1A when expressed in Xenopus oocytes. Furthermore, BmABCC2 had a high binding affinity (KD) to Cry1Aa of 3.1 × 10-10 M. These findings suggest that ABC transporters, including ABCC2 and ABCB1, are functional receptors for 3D-Cry toxins. In addition, the Cry2 toxins most distant from Cry1A toxins on the phylogenetic tree used ABC transporter A2 as a receptor. These data suggest that 3D-Cry toxins use ABC transporters as receptors. In terms of inducing cell swelling, ABCC2 has greater activity than cadherin-like receptor. The pore opening of ABC transporters was hypothesized to be linked to their receptor function, but this was repudiated by experiments using mutants deficient in export activity. The synergistic relationship between ABCC2 and cadherin-like receptor explains their ability to cause resistance in one species of insect.
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Affiliation(s)
- Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan.
| | - Satomi Adegawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan.
| | - Xiaoyi Li
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan.
| | - Shiho Tanaka
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan.
| | - Haruka Endo
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka 2-24-16, Koganei, Tokyo 184-8588, Japan.
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24
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Martínez-Solís M, Pinos D, Endo H, Portugal L, Sato R, Ferré J, Herrero S, Hernández-Martínez P. Role of Bacillus thuringiensis Cry1A toxins domains in the binding to the ABCC2 receptor from Spodoptera exigua. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 101:47-56. [PMID: 30077769 DOI: 10.1016/j.ibmb.2018.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/24/2018] [Accepted: 07/29/2018] [Indexed: 06/08/2023]
Abstract
Cry proteins from Bacillus thuringiensis (Bt) have been used to control insect pests either as formulated sprays or as in Bt-crops. However, field-evolved resistance to Bt proteins is threatening the long-term use of Bt products. The SeABCC2 locus has been genetically linked to resistance to a Bt bioinsecticide (Xentari™) in Spodoptera exigua (a mutation producing a truncated form of the transporter lacking an ATP binding domain was found in the resistant insects). Here, we investigated the role of SeABCC2 in the mode of action of Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ca, and two Cry1A-1Ca hybrids by expressing the receptor in Sf21 and HEK293T cell lines. Cell toxicity assays showed that Sf21 cells expressing SeABCC2 become susceptible to Cry1A proteins. HEK293T cells expressing the transporter were found susceptible to Cry1A proteins but not to Cry1Ca. The results with the Cry1A-1Ca hybrids suggest that domain II from Cry1Ab/c is crucial for the toxicity to Sf21 cells, whereas domain III from Cry1Aa/b is crucial for the toxicity to HEK293T cells. Binding assays showed that the Cry1Ac binding is of high affinity and specific to cells expressing the SeABCC2 transporter. Heterologous competition experiments support a model in which domain II of Cry1Ab/c has a common binding site in the SeABCC2 protein, whereas domain III of Cry1Aa/b binds to a different binding site in the SeABCC2 protein.
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Affiliation(s)
- María Martínez-Solís
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain
| | - Daniel Pinos
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain
| | - Haruka Endo
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Leivi Portugal
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Juan Ferré
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain
| | - Salvador Herrero
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain
| | - Patricia Hernández-Martínez
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain.
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Endo H, Tanaka S, Adegawa S, Ichino F, Tabunoki H, Kikuta S, Sato R. Extracellular loop structures in silkworm ABCC transporters determine their specificities for Bacillus thuringiensis Cry toxins. J Biol Chem 2018; 293:8569-8577. [PMID: 29666188 DOI: 10.1074/jbc.ra118.001761] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 04/11/2018] [Indexed: 12/20/2022] Open
Abstract
Bacillus thuringiensis Cry toxins are insecticidal proteins used widely for pest control. They are lethal to a restricted range of insects via specific interactions with insect receptors such as the ABC transporter subfamily members C2 (ABCC2) and C3 (ABCC3). However, it is still unclear how these different receptors contribute to insect susceptibility to Cry1A toxins. Here, we investigated the differences between the silkworm (Bombyx mori) ABCC2 (BmABCC2_S) and ABCC3 (BmABCC3) receptors in mediating Cry toxicity. Compared with BmABCC2_S, BmABCC3 exhibited 80- and 267-fold lower binding affinities to Cry1Aa and Cry1Ab, respectively, and these decreased affinities correlated well with the lower receptor activities of BmABCC3 for these Cry1A toxins. To identify the amino acid residues responsible for these differences, we constructed BmABCC3 variants containing a partial amino acid replacement with extracellular loops (ECLs) from BmABCC2_S. Replacing three amino acids from ECL 1 or 3 increased BmABCC3 activity toward Cry1Aa and enabled its activity toward Cry1Ab. Meanwhile, BmABCC2_S and BmABCC3 exhibited no receptor activities for Cry1Ca, Cry1Da, and Cry3Bb, correlating with markedly lower binding affinities for these Cry toxins. ABCC2 from a Cry1Ab-resistant B. mori strain (BmABCC2_R), which has a tyrosine insertion in ECL 2, displayed 93-fold lower binding affinity to Cry1Ab compared with BmABCC2_S but maintained high binding affinity to Cry1Aa. These results indicate that the Cry toxin-binding affinities of ABCC transporters are largely linked to the level of Cry susceptibility of ABCC-expressing cells and that the ABCC ECL structures determine the specificities to Cry toxins.
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Affiliation(s)
- Haruka Endo
- From the Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan and
| | - Shiho Tanaka
- From the Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan and
| | - Satomi Adegawa
- From the Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan and
| | - Fumika Ichino
- the Department of Science of Biological Production, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Saiwai-cho 3-5-8, Fuchu, Tokyo 183-8509, Japan
| | - Hiroko Tabunoki
- the Department of Science of Biological Production, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Saiwai-cho 3-5-8, Fuchu, Tokyo 183-8509, Japan
| | - Shingo Kikuta
- From the Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan and
| | - Ryoichi Sato
- From the Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan and
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26
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Recent advancement on chemical arsenal of Bt toxin and its application in pest management system in agricultural field. 3 Biotech 2018; 8:201. [PMID: 29607282 DOI: 10.1007/s13205-018-1223-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 03/22/2018] [Indexed: 10/17/2022] Open
Abstract
Bacillus thuringiensis (Bt) is a Gram-positive, spore-forming, soil bacterium, which is very popular bio-control agent in agricultural and forestry. In general, B. thuringiensis secretes an array of insecticidal proteins including toxins produced during vegetative growth phase (such as secreted insecticidal protein, Sip; vegetative insecticidal proteins, Vip), parasporal crystalline δ-endotoxins produced during vegetative stationary phase (such as cytolytic toxin, Cyt; and crystal toxin, Cry), and β-exotoxins. Till date, a wide spectrum of Cry proteins has been reported and most of them belong to three-domain-Cry toxins, Bin-like toxin, and Etx_Mtx2-like toxins. To the best of our knowledge, neither Bt insecticidal toxins are exclusive to Bt nor all the strains of Bt are capable of producing insecticidal Bt toxins. The lacuna in their latest classification has also been discussed. In this review, the updated information regarding the insecticidal Bt toxins and their different mode of actions were summarized. Before applying the Bt toxins on agricultural field, the non-specific effects of toxins should be investigated. We also have summarized the problem of insect resistance and the strategies to combat with this problem. We strongly believe that this information will help a lot to the budding researchers in the field of modern pest control biotechnology.
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Silva LM, Silva MC, Silva SMFA, Alves RC, Siqueira HAA, Marques EJ. Toxin Gene Contents and Activity of Bacillus thuringiensis Strains Against Two Sugarcane Borer Species, Diatraea saccharalis (F.) and D. flavipennella (Box). NEOTROPICAL ENTOMOLOGY 2018; 47:292-301. [PMID: 28866859 DOI: 10.1007/s13744-017-0558-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 08/22/2017] [Indexed: 06/07/2023]
Abstract
Bacillus thuringiensis (Berliner) bears essential characteristics in the control of insect pests, such as its unique mode of action, which confers specificity and selectivity. This study assessed cry gene contents from Bt strains and their entomotoxicity against Diatraea saccharalis (F.) and Diatraea flavipennella (Box) (Lepidoptera: Crambidae). Bioassays with Bt strains were performed against neonates to evaluate their lethal and sublethal activities and were further analyzed by PCR, using primers to identify toxin genes. For D. saccharalis and D. flavipennella, 16 and 18 strains showed over 30% larval mortality in the 7th day, respectively. The LC50 values of strains for D. saccharalis varied from 0.08 × 105 (LIIT-0105) to 4104 × 105 (LIIT-2707) spores + crystals mL-1. For D. flavipennella, the LC50 values of strains varied from 0.40 × 105 (LIIT-2707) to 542 × 105 (LIIT-2109) spores + crystals mL-1. For the LIIT-0105 strain, which was the most toxic to D. saccharalis, the genes cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, cry8, and cry9C were detected, whereas for the strain LIIT-2707, which was the most toxic to D. flavipennella, detected genes were cry1Aa, cry1Ab, cry1Ac, cry1B, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, and cry9. The toxicity data and toxin gene content in these strains of Bt suggest a great variability of activity with potential to be used in the development of novel biopesticides or as source of resistance genes that can be expressed in plants to control pests.
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Affiliation(s)
- L M Silva
- Depto de Agronomia, PPGEA, Fitossanidade, Entomologia Agrícola, Univ Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, 52171-900, Brasil.
| | - M C Silva
- Depto de Química e Biologia, Univ Estadual do Maranhão, Caxias, MA, Brasil
| | - S M F A Silva
- Depto de Agronomia, PPGEA, Fitossanidade, Entomologia Agrícola, Univ Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, 52171-900, Brasil
| | - R C Alves
- Depto de Agronomia, PPGEA, Fitossanidade, Entomologia Agrícola, Univ Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, 52171-900, Brasil
| | - H A A Siqueira
- Depto de Agronomia, PPGEA, Fitossanidade, Entomologia Agrícola, Univ Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, 52171-900, Brasil
| | - E J Marques
- Depto de Agronomia, PPGEA, Fitossanidade, Entomologia Agrícola, Univ Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, 52171-900, Brasil
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