Insect Biochemistry and Molecular Biology最新文献

{"title":"Single-nucleus sequencing of silkworm larval midgut reveals the immune escape strategy of BmNPV in the midgut during the late stage of infection","authors":"Junming Xia ,&nbsp;Shigang Fei ,&nbsp;Yigui Huang ,&nbsp;Wenxuan Lai ,&nbsp;Yue Yu ,&nbsp;Lingying Liang ,&nbsp;Hailin Wu ,&nbsp;Luc Swevers ,&nbsp;Jingchen Sun ,&nbsp;Min Feng","doi":"10.1016/j.ibmb.2023.104043","DOIUrl":"10.1016/j.ibmb.2023.104043","url":null,"abstract":"<div><p><span><span>The midgut is an important barrier against microorganism invasion and proliferation, yet is the first tissue encountered when a baculovirus naturally invades the host. However, only limited knowledge is available how different midgut cell types contribute to the immune response and the clearance or promotion of viral infection. Here, single-nucleus </span>RNA sequencing<span> (snRNA seq) was employed to analyze the responses of various cell subpopulations in the silkworm larval midgut to </span></span><span><em>B. </em><em>mori</em></span><span><span> nucleopolyhedrovirus (BmNPV) infection. We identified 22 distinct clusters representing enteroendocrine cells<span> (EEs), enterocytes (ECs), intestinal </span></span>stem cells<span> (ISCs), Goblet cell-like and muscle cell types in the BmNPV-infected and uninfected silkworm larvae midgut at 72 h post infection. Further, our results revealed that the strategies for immune escape of BmNPV in the midgut at the late stage of infection include (1) inhibiting the response of antiviral pathways; (2) inhibiting the expression of antiviral host factors; (3) stimulating expression levels of genes promoting BmNPV replication. These findings suggest that the midgut, as the first line of defense against the invasion of the baculovirus, has dual characteristics of \"resistance\" and \"tolerance\". Our single-cell dataset reveals the diversity of silkworm larval midgut cells, and the transcriptome analysis provides insights into the interaction between host and virus infection at the single-cell level.</span></span></p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"164 ","pages":"Article 104043"},"PeriodicalIF":3.8,"publicationDate":"2023-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138443305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Different myrosinases activate sequestered glucosinolates in larvae and adults of the horseradish flea beetle","authors":"Johannes Körnig ,&nbsp;Kris Ortizo ,&nbsp;Theresa Sporer ,&nbsp;Zhi-Ling Yang ,&nbsp;Franziska Beran","doi":"10.1016/j.ibmb.2023.104040","DOIUrl":"10.1016/j.ibmb.2023.104040","url":null,"abstract":"<div><p>β-Glucosidases play an important role in the chemical defense of many insects by hydrolyzing and thereby activating glucosylated pro-toxins that are either synthesized <em>de novo</em> or sequestered from the insect's diet. The horseradish flea beetle, <em>Phyllotreta armoraciae</em>, sequesters pro-toxic glucosinolates from its brassicaceous host plants and possesses endogenous <em>β</em>-thioglucosidase enzymes, known as myrosinases, for glucosinolate activation. Here, we identify three myrosinase genes in <em>P. armoraciae</em> (<em>PaMyr</em>) with distinct expression patterns during beetle ontogeny. By using RNA interference, we demonstrate that <em>PaMyr1</em> is responsible for myrosinase activity in adults, whereas <em>PaMyr2</em> is responsible for myrosinase activity in larvae. Compared to <em>PaMyr1</em> and <em>PaMyr2</em>, <em>PaMyr3</em> was only weakly expressed in our laboratory population, but may contribute to myrosinase activity in larvae. Silencing of <em>PaMyr2</em> resulted in lower larval survival in a predation experiment and also reduced the breakdown of sequestered glucosinolates in uninjured larvae. This suggests that PaMyr2 is involved in both activated defense and the endogenous turnover of sequestered glucosinolates in <em>P. armoraciae</em> larvae. In activity assays with recombinant enzymes, PaMyr1 and PaMyr2 preferred different glucosinolates as substrates, which was consistent with the enzyme activities in crude protein extracts from adults and larvae, respectively. These differences were unexpected because larvae and adults sequester the same glucosinolates. Possible reasons for different myrosinase activities in <em>Phyllotreta</em> larvae and adults are discussed.</p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"163 ","pages":"Article 104040"},"PeriodicalIF":3.8,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0965174823001340/pdfft?md5=1815c9718fc2f2040f147ace24a130dc&pid=1-s2.0-S0965174823001340-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138297970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contrasting roles of cytochrome P450s in amitraz and chlorfenapyr resistance in the crop pest Tetranychus urticae","authors":"Marilou Vandenhole ,&nbsp;Xueping Lu ,&nbsp;Dimitra Tsakireli ,&nbsp;Catherine Mermans ,&nbsp;Sander De Rouck ,&nbsp;Berdien De Beer ,&nbsp;Eba Simma ,&nbsp;Spiros A. Pergantis ,&nbsp;Wim Jonckheere ,&nbsp;John Vontas ,&nbsp;Thomas Van Leeuwen","doi":"10.1016/j.ibmb.2023.104039","DOIUrl":"10.1016/j.ibmb.2023.104039","url":null,"abstract":"<div><p><span>The molecular mechanisms of amitraz and chlorfenapyr resistance remain only poorly understood for major agricultural pests and vectors of human diseases. This study focusses on a multi-resistant field strain of the crop pest </span><span><em>Tetranychus urticae</em></span><span><span>, which could be readily selected in the laboratory to high levels of amitraz and chlorfenapyr resistance. Toxicity experiments using tralopyril, the active toxophore of chlorfenapyr, suggested decreased activation as a likely mechanism underlying resistance. Starting from the same parental strain, transcriptome profiling revealed that a cluster of detoxifying genes was upregulated after amitraz selection, but unexpectedly downregulated after chlorfenapyr selection. Further functional validation associated the upregulation of CYP392A16 with amitraz metabolism and the downregulation of CYP392D8 with reduced activation of chlorfenapyr to tralopyril. Genetic mapping (QTL analysis by BSA) was conducted in an attempt to unravel the </span>genetic mechanisms of expression variation and resistance. This revealed that chlorfenapyr resistance was associated with a single QTL, while 3 QTLs were uncovered for amitraz resistance. Together with the observed contrasting gene expression patterns, we argue that transcriptional regulators most likely underly the distinct expression profiles associated with resistance, but these await further functional validation.</span></p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"164 ","pages":"Article 104039"},"PeriodicalIF":3.8,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138294344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional annotation of insecta transcriptomes: A cautionary tale from Lepidoptera","authors":"Naya McCartney ,&nbsp;Gayathri Kondakath ,&nbsp;Albert Tai ,&nbsp;Barry A. Trimmer","doi":"10.1016/j.ibmb.2023.104038","DOIUrl":"10.1016/j.ibmb.2023.104038","url":null,"abstract":"<div><p><span>Functional annotation is a critical step in the analysis of genomic data, as it provides insight into the function of individual genes and the pathways in which they participate. Currently, there is no consensus on the best computational approach for assigning functional annotation. This study compares three functional annotation methods (BLAST, eggNOG-Mapper, and InterProScan) in their ability to assign Gene Ontology terms in two species of Insecta with differing levels of annotation, </span><span><em>Bombyx mori</em></span> and <span><em>Manduca sexta</em></span>. The methods were compared for their annotation coverage, number of term assignments, term agreement and non-overlapping terms. Here we show that there are large discrepancies in gene ontology term assignment among the three computational methods, which could lead to confounding interpretations of data and non-comparable results. This study provide insight into the strengths and weaknesses of each computational method and highlight the need for more standardized methods of functional annotation.</p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"165 ","pages":"Article 104038"},"PeriodicalIF":3.8,"publicationDate":"2023-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89716239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ABC transporter subfamily B1 as a susceptibility determinant of Bombyx mori larvae to Cry1Ba, Cry1Ia and Cry9Da toxins","authors":"Kana Iwabuchi ,&nbsp;Kazuhisa Miyamoto ,&nbsp;Akiya Jouraku ,&nbsp;Yoko Takasu ,&nbsp;Tetsuya Iizuka ,&nbsp;Satomi Adegawa ,&nbsp;Xiaoyi Li ,&nbsp;Ryoichi Sato ,&nbsp;Kenji Watanabe","doi":"10.1016/j.ibmb.2023.104030","DOIUrl":"10.1016/j.ibmb.2023.104030","url":null,"abstract":"<div><p><span><span>ATP binding cassette (ABC) transporters are a diverse family of transmembrane proteins. Specific subfamily members expressed in the </span>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 </span><span><span>Bombyx mori</span></span> 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 <em>B. mori</em> 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 <span><em>Plutella xylostella</em></span><span> 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<span> is based on receptor function, we performed surface plasmon resonance analysis and found that each </span></span><em>KD</em> 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.</p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"163 ","pages":"Article 104030"},"PeriodicalIF":3.8,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89716238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Histochemistry and transcriptomics of mucins and peritrophic membrane (PM) proteins along the midgut of a beetle with incomplete PM and their complementary function","authors":"Samira P. Ibrahim ,&nbsp;Renata O. Dias ,&nbsp;Clelia Ferreira ,&nbsp;Carlos P. Silva ,&nbsp;Walter R. Terra","doi":"10.1016/j.ibmb.2023.104027","DOIUrl":"10.1016/j.ibmb.2023.104027","url":null,"abstract":"<div><p>The midgut of <span><em>Zabrotes subfasciatus</em></span><span> (Coleoptera) and other insects may have regions lacking a peritrophic membrane<span><span> (matrix, PM) and covered with a jelly-like material known as peritrophic gel. This work was undertaken to test the hypothesis that the peritrophic gel is a vertebrate-like mucus. By histochemistry<span> we identified mucins along the whole midgut, which contrasts with the known occurrence of PM only at the posterior midgut. We also analyzed the expression of the genes coding for mucus-forming mucins (Mf-mucins), peritrophins, chitin synthases<span> and chitin<span><span> deacetylases along the midgut and carcass (insect without midgut) by RNA-seq. Mf-mucins were identified as proteins with high O-glycosylation and multiple tandem repeats of Pro/Thr/Ser residues. Peritrophins were separated into PM proteins, cuticular proteins analogous to peritrophins (CPAPs) and ubiquitous-chitin-binding domain-(CBD)-containing proteins (UCBPs). PM proteins have at least 3, CPAP one or 3, and UCBPs have a varied number of CBDs. PM proteins are more expressed at midgut, CPAP at the carcass, and UCBP at both. The results showed that most PM proteins are mainly expressed at the posterior midgut, together with midgut </span>chitin synthase and chitin deacetylase, and in agreement with the presence of PM only at the posterior midgut by visual inspection. The excretion of most midgut </span></span></span></span>chitinase<span> is avoided, suggesting that the shortened PM is functional. Mf-mucins are expressed along the whole midgut, probably forming the extracellular mucus layer observed by histochemistry. Thus, the lack of PM at anterior and middle midgut causes the exposure of a mucus, which may correspond to the previously described peritrophic gel. The putative functional interplay of mucus and PM is discussed. The major role of mucus is proposed to be tissue protection and of PM to enhancing digestive efficiency by allowing enzyme recycling.</span></span></span></p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"162 ","pages":"Article 104027"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41187071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pyruvate kinase is post-translationally regulated by sirtuin 2 in Aedes aegypti mosquitoes","authors":"Natthida Petchampai ,&nbsp;Jun Isoe ,&nbsp;Prashanth Balaraman ,&nbsp;Max Oscherwitz ,&nbsp;Brendan H. Carter ,&nbsp;Cecilia G. Sánchez ,&nbsp;Patricia Y. Scaraffia","doi":"10.1016/j.ibmb.2023.104015","DOIUrl":"10.1016/j.ibmb.2023.104015","url":null,"abstract":"<div><p>We previously demonstrated that <em>Aedes aegypti</em> pyruvate kinase (AaPK) plays a key role in the regulation of both carbon and nitrogen metabolism in mosquitoes. To further elucidate whether AaPK can be post-translationally regulated by <em>Ae. aegypti</em> sirtuin 2 (AaSirt2), an NAD⁺-dependent deacetylase that catalyzes the removal of acetyl groups from acetylated lysine residues, we conducted a series of analysis in non-starved and starved female mosquitoes. Transcriptional and protein profiles of AaSirt2, analyzed by qPCR and western blots, indicated that the AaSirt2 is differentially modulated in response to sugar or blood feeding in mosquito tissues dissected at different times during the first gonotrophic cycle. We also found that AaSirt2 is localized in both cytosolic and mitochondrial cellular compartments of fat body and thorax. Multiple lysine-acetylated proteins were detected by western blotting in both cellular compartments. Furthermore, western blotting of immunoprecipitated proteins provided evidence that AaPK is lysine-acetylated and bound with AaSirt2 in the cytosolic fractions of fat body and thorax from non-starved and starved females. In correlation with these results, we also discovered that RNAi-mediated knockdown of AaSirt2 in the fat body of starved females significantly decreased AaPK protein abundance. Notably, survivorship of AaSirt2-deficient females maintained under four different nutritional regimens was not significantly affected. Taken together, our data reveal that AaPK is post-translationally regulated by AaSirt2.</p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"162 ","pages":"Article 104015"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0965174823001091/pdfft?md5=c8566d3345fa8536fd055e841163f056&pid=1-s2.0-S0965174823001091-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41093819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pea aphid odorant-binding protein ApisOBP6 discriminates between aphid sex pheromone components, aphid alarm pheromone and a host plant volatile","authors":"Cassie Sims ,&nbsp;Michael A. Birkett ,&nbsp;Neil J. Oldham ,&nbsp;Robert A. Stockman ,&nbsp;David M. Withall","doi":"10.1016/j.ibmb.2023.104026","DOIUrl":"10.1016/j.ibmb.2023.104026","url":null,"abstract":"<div><p>Olfactory perception of pheromones in insects involves odorant-binding proteins (OBPs), relatively small proteins (ca.110-240 amino acid residues) that can bind reversibly to behaviourally active olfactory ligands. In this study, we investigated the binding <em>in silico</em> and <em>in vitro</em> of the aphid sex pheromone components (1<em>R</em>,4a<em>S</em>,7<em>S</em>,7a<em>R</em>)-nepetalactol and (4a<em>S</em>,7<em>S</em>,7a<em>R</em>)-nepetalactone and the aphid alarm pheromone (<em>E</em>)-β-farnesene by OBPs from the pea aphid, <em>Acyrthosiphon pisum.</em> Screening of protein models of ApisOBPs1-11 with the aphid sex pheromone components suggested that ApisOPB6 was a candidate<strong>.</strong> Fluorescence assays using ApisOBP6 suggested that ApisOBP6 was able to bind both sex pheromone components and discriminate from the aphid alarm pheromone and the generic plant compound (<em>R/S</em>)-linalool. Saturation transfer difference NMR experiments with ApisOBP6 yielded results consistent to those from the fluorescence experiments, with a clear interaction between ApisOBP6 and (4a<em>S</em>,7<em>S</em>,7a<em>R</em>)-nepetalactone. These results describe a novel interaction and potential function for ApisOBP6, point to pre-receptor odorant discrimination by OBPs, and provide a platform for investigating the function of other aphid olfactory proteins involved in aphid chemical ecology.</p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"162 ","pages":"Article 104026"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0965174823001200/pdfft?md5=04c254ab70f55d837000c64829fda4a1&pid=1-s2.0-S0965174823001200-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41187072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diuretic hormone 31 activates two G protein-coupled receptors with differential second messengers for diuresis in Drosophila suzukii","authors":"Ho Jung Yoon ,&nbsp;Briana E. Price ,&nbsp;Ryssa K. Parks ,&nbsp;Seung-Joon Ahn ,&nbsp;Man-Yeon Choi","doi":"10.1016/j.ibmb.2023.104025","DOIUrl":"10.1016/j.ibmb.2023.104025","url":null,"abstract":"<div><p><span><span>Diuretic hormones (DHs) bind to G protein-coupled receptors (GPCRs), regulating water and ion balance to maintain </span>homeostasis<span> in animals. Two distinct DHs are known in insects: calcitonin (CT)-like DH31 and corticotropin-releasing factor (CRF)-like DH44. In this study, we identified and characterized DH31 and two DH31 GPCR variants, DH31-Ra and DH31-Rb, from spotted-wing drosophila, </span></span><span><em>Drosophila suzukii</em></span><span><span><span>, a globally prevalent vinegar fly causing severe damage to small fruits. Both GPCRs are active, but DH31-Ra is the dominant receptor based on gene expression analyses and DH31 peptide </span>binding affinities<span><span><span>. A notable difference between the two variants lies in 1) the GPCR structures of their C-termini and 2) the utilization of second messengers, and the </span>amino acid sequences of the two variants are identical. DH31-Ra contains 12 additional </span>amino acids, providing different intracellular C-terminal configurations. DH31-Ra utilizes both </span></span>cAMP and Ca</span>²⁺ as second messengers, whereas DH31-Rb utilizes only cAMP; this is the first time reported for an insect CT-like DH31 peptide. DH31 stimulated fluid secretion in <em>D. suzukii</em><span><span> adults, and secretion increased in a dose-dependent manner. However, when the fly was injected with a mixture of DH31 and CAPA, an anti-diuretic hormone, fluid secretion was suppressed. Here, we discuss the structures of the DH31 receptors and the differential signaling pathways, including second messengers, involved in fly </span>diuresis. These findings provide fundamental insights into the characterization of </span><em>D. suzukii</em> DH31 and DH31-Rs, and facilitate the identification of potential biological targets for <em>D. suzukii</em> management.</p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"162 ","pages":"Article 104025"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41181621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystal structures of PirA and PirB toxins from Photorhabdus akhurstii subsp. akhurstii K-1","authors":"Arpit Prashar ,&nbsp;Omkar U. Kinkar ,&nbsp;Ashwani Kumar ,&nbsp;Ashok B. Hadapad ,&nbsp;Ravindra D. Makde ,&nbsp;Ramesh S. Hire","doi":"10.1016/j.ibmb.2023.104014","DOIUrl":"10.1016/j.ibmb.2023.104014","url":null,"abstract":"<div><p>PirAB binary toxin from <span><em>Photorhabdus</em></span><span> is toxic to the larvae of dipteran and lepidopteran<span> insect pests. However, the 3-D structures and their toxicity mechanism are not yet fully understood. Here we report the crystal structures of PirA and PirB proteins from </span></span><em>Photorhabdus akhurstii</em> subsp. <em>akhurstii</em> K-1 at 1.6 and 2.1 Å, respectively. PirA comprises of eight β-strands depicting jelly-roll topology while PirB folds into two distinct domains, an N-terminal domain (PirB-N) made up of seven α-helices and a C-terminal domain (PirB-C) consists of ten β-strands. Despite the low sequence identity, PirA adopts similar architecture as domain III and PirB shared similar architecture as domain I/II of the Cry δ-endotoxin of <span><em>Bacillus thuringiensis</em></span><span>, respectively. However, PirA shows significant structural variations as compared to domain III of lepidopteran and dipteran specific Cry toxins (Cry1Aa and Cry11Ba) suggesting its role in virulence among range of insect pests and hence, in receptor binding. High structural resemblance between PirB-N and domain I of Cry toxin raises the possibility that the putative PirAB binary toxin may mimic the toxicity mechanism of the Cry protein, particularly its ability to perform pore formation. The mixture of independently purified PirA and PirB proteins are not toxic to insects. However, PirA-PirB protein complex purified from expression of </span><em>pir</em> operon with non-coding Enterobacterial Repetitive Intergenic Consensus (ERIC) sequences found toxic to <span><em>Galleria mellonella</em></span> larvae with LD₅₀ value of 1.62 μg/larva. This suggests that toxic conformation of PirA and PirB are achieved <em>in-vivo</em> with the help of ERIC sequences.</p></div>","PeriodicalId":330,"journal":{"name":"Insect Biochemistry and Molecular Biology","volume":"162 ","pages":"Article 104014"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41094442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}