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Zhang Y, Zhang S, Xu L. The pivotal roles of gut microbiota in insect plant interactions for sustainable pest management. NPJ Biofilms Microbiomes 2023; 9:66. [PMID: 37735530 PMCID: PMC10514296 DOI: 10.1038/s41522-023-00435-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 09/11/2023] [Indexed: 09/23/2023] Open
Abstract
The gut microbiota serves as a critical "organ" in the life cycle of animals, particularly in the intricate interplay between herbivorous pests and plants. This review summarizes the pivotal functions of the gut microbiota in mediating the insect-plant interactions, encompassing their influence on host insects, modulation of plant physiology, and regulation of the third trophic level species within the ecological network. Given these significant functions, it is plausible to harness these interactions and their underlying mechanisms to develop novel eco-friendly pest control strategies. In this context, we also outline some emerging pest control methods based on the intestinal microbiota or bacteria-mediated interactions, such as symbiont-mediated RNAi and paratransgenesis, albeit these are still in their nascent stages and confront numerous challenges. Overall, both opportunities and challenges coexist in the exploration of the intestinal microbiota-mediated interactions between insect pests and plants, which will not only enrich the fundamental knowledge of plant-insect interactions but also facilitate the development of sustainable pest control strategies.
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Affiliation(s)
- Yuxin Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062, Wuhan, China
| | - Shouke Zhang
- State Key Laboratory of Subtropical Silviculture, Zhejiang A & F University, 311300, Hangzhou, China.
| | - Letian Xu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, 430062, Wuhan, China.
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2
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Identification and Functional Analysis of a Pseudo-Cysteine Protease from the Midgut Transcriptome of Sphenophorus levis. Int J Mol Sci 2021; 22:ijms222111476. [PMID: 34768909 PMCID: PMC8583781 DOI: 10.3390/ijms222111476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/08/2021] [Accepted: 10/19/2021] [Indexed: 11/16/2022] Open
Abstract
The Sphenophorus levis (Coleoptera, Curculionidae) is one of the main pests of sugarcane in Brazil. Although its major digestive proteases are known, its complex digestive process still needs to be further understood. We constructed a transcriptome from the midgut of 30-day-old larvae and identified sequences similar to its major digestive protease (cysteine cathepsin Sl-CathL), however, they presented a different amino acid than cysteine in the active cleft. We identified, recombinantly produced, and characterized Sl-CathL-CS, a pseudo cysteine protease, and verified that higher gene expression levels of Sl-CathL-CS occur in the midgut of 30-day old larvae. We reverted the serine residue to cysteine and compared the activity of the mutant (Sl-CathL-mutSC) with Sl-CathL-CS. Sl-CathL-CS presented no protease activity, but Sl-CathL-mutSC hydrolyzed Z-Phe-Arg-AMC (Vmax = 1017.60 ± 135.55, Km = 10.77 mM) and was inhibited by a cysteine protease inhibitor E-64 (Ki = 38.52 ± 1.20 μM), but not by the serine protease inhibitor PMSF. Additionally, Sl-CathL-CS interacted with a sugarcane cystatin, while Sl-CathL-mutSC presented weaker interaction. Finally, protein ligand docking reinforced the differences in the catalytic sites of native and mutant proteins. These results indicate that Sl-CathL-CS is a pseudo-cysteine protease that assists protein digestion possibly by interacting with canecystatins, allowing the true proteases to work.
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Gao P, Liu Z, Wen J. Expression Profiling of Plant Cell Wall-Degrading Enzyme Genes in Eucryptorrhynchus scrobiculatus Midgut. Front Physiol 2020; 11:1111. [PMID: 33013475 PMCID: PMC7500146 DOI: 10.3389/fphys.2020.01111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/11/2020] [Indexed: 11/17/2022] Open
Abstract
In China, the wood-boring weevil Eucryptorrhynchus scrobiculatus damages and eventually kills the tree of heaven Ailanthus altissima. To feed and digest the cell wall of A. altissima, E. scrobiculatus requires plant cell wall-degrading enzymes (PCWDEs). In the present study, we used next-generation sequencing to analyze the midgut transcriptome of E. scrobiculatus. Using three midgut transcriptomes, we assembled 21,491 unigenes from 167,714,100 clean reads. We identified 25 putative PCWDEs, including 11 cellulases and 14 pectinases. We constructed phylogenetic trees with a maximum likelihood algorithm to elucidate the relationships between sequences of the PCWDE protein families and speculate the functions of the PCWDE genes in E. scrobiculatus. The expression patterns of 17 enzymes in the midgut transcriptome were analyzed in various tissues by quantitative real-time PCR (RT-qPCR). The relative expression levels of 12 genes in the midgut and two genes in the proboscis were significantly higher than those in the other tissues. The proboscis and midgut are the digestive organs of insects, and the high expression level indirectly indicates that these genes are related to digestion. The present study has enabled us to understand the types and numbers of the PCWDEs of E. scrobiculatus and will be helpful for research regarding other weevils’ PCWDEs in the future.
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Affiliation(s)
- Peng Gao
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing, China
| | - Zhenkai Liu
- Research Institute of Forestry New Technology, Chinese Academy of Forestry, Beijing, China
| | - Junbao Wen
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing, China
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Biochemical characterization and low-resolution SAXS shape of a novel GH11 exo-1,4-β-xylanase identified in a microbial consortium. Appl Microbiol Biotechnol 2019; 103:8035-8049. [PMID: 31407040 DOI: 10.1007/s00253-019-10033-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 07/15/2019] [Accepted: 07/15/2019] [Indexed: 10/26/2022]
Abstract
Biotechnologies that aim to produce renewable fuels, chemicals, and bioproducts from residual ligno(hemi)cellulosic biomass mostly rely on enzymatic depolymerization of plant cell walls (PCW). This process requires an arsenal of diverse enzymes, including xylanases, which synergistically act on the hemicellulose, reducing the long and complex xylan chains to oligomers and simple sugars. Thus, xylanases play a crucial role in PCW depolymerization. Until recently, the largest xylanase family, glycoside hydrolase family 11 (GH11) has been exclusively represented by endo-catalytic β-1,4- and β-1,3-xylanases. Analysis of a metatranscriptome library from a microbial lignocellulose community resulted in the identification of an unusual exo-acting GH11 β-1,4-xylanase (MetXyn11). Detailed characterization has been performed on recombinant MetXyn11 including determination of its low-resolution small-angle X-ray scattering (SAXS) molecular envelope in solution. Our results reveal that MetXyn11 is a monomeric globular enzyme that liberates xylobiose from heteroxylans as the only product. MetXyn11 has an optimal activity in a pH range from 6 to 9 and an optimal temperature of 50 °C. The enzyme maintained above 65% of its original activity in the pH range 5 to 6 after being incubated for 72 h at 50 °C. Addition of the enzyme to a commercial enzymatic cocktail (CelicCtec3) promoted a significant increase of enzymatic hydrolysis yields of hydrothermally pretreated sugarcane bagasse (16% after 24 h of hydrolysis).
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Kirsch R, Kunert G, Vogel H, Pauchet Y. Pectin Digestion in Herbivorous Beetles: Impact of Pseudoenzymes Exceeds That of Their Active Counterparts. Front Physiol 2019; 10:685. [PMID: 31191365 PMCID: PMC6549527 DOI: 10.3389/fphys.2019.00685] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 05/16/2019] [Indexed: 12/11/2022] Open
Abstract
Many protein families harbor pseudoenzymes that have lost the catalytic function of their enzymatically active counterparts. Assigning alternative function and importance to these proteins is challenging. Because the evolution toward pseudoenzymes is driven by gene duplication, they often accumulate in multigene families. Plant cell wall-degrading enzymes (PCWDEs) are prominent examples of expanded gene families. The pectolytic glycoside hydrolase family 28 (GH28) allows herbivorous insects to break down the PCW polysaccharide pectin. GH28 in the Phytophaga clade of beetles contains many active enzymes but also many inactive counterparts. Using functional characterization, gene silencing, global transcriptome analyses, and recordings of life history traits, we found that not only catalytically active but also inactive GH28 proteins are part of the same pectin-digesting pathway. The robustness and plasticity of this pathway and thus its importance for the beetle is supported by extremely high steady-state expression levels and counter-regulatory mechanisms. Unexpectedly, the impact of pseudoenzymes on the pectin-digesting pathway in Phytophaga beetles exceeds even the influence of their active counterparts, such as a lowered efficiency of food-to-energy conversion and a prolongation of the developmental period.
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Affiliation(s)
- Roy Kirsch
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Grit Kunert
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Heiko Vogel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Yannick Pauchet
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
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Vicente CSL, Nemchinov LG, Mota M, Eisenback JD, Kamo K, Vieira P. Identification and characterization of the first pectin methylesterase gene discovered in the root lesion nematode Pratylenchus penetrans. PLoS One 2019; 14:e0212540. [PMID: 30794636 PMCID: PMC6386239 DOI: 10.1371/journal.pone.0212540] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 02/05/2019] [Indexed: 02/04/2023] Open
Abstract
Similar to other plant-parasitic nematodes, root lesion nematodes possess an array of enzymes that are involved in the degradation of the plant cell wall. Here we report the identification of a gene encoding a cell wall-degrading enzyme, pectin methylesterase PME (EC 3.1.1.11), in the root lesion nematode Pratylenchus penetrans. Both genomic and coding sequences of the gene were cloned for this species, that included the presence of four introns which eliminated a possible contamination from bacteria. Expression of the Pp-pme gene was localized in the esophageal glands of P. penetrans as determined by in situ hybridization. Temporal expression of Pp-pme in planta was validated at early time points of infection. The possible function and activity of the gene were assessed by transient expression of Pp-pme in plants of Nicotiana benthamiana plants via a Potato virus X-based vector. To our knowledge, this is the first report on identification and characterization of a PME gene within the phylum Nematoda.
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Affiliation(s)
- Cláudia S. L. Vicente
- ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Instituto de Investigação e Formação Avançada, Universidade de Évora, Pólo da Mitra, Évora, Portugal
| | - Lev G. Nemchinov
- Molecular Plant Pathology Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States of America
| | - Manuel Mota
- Departamento de Biologia & ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de Évora, Pólo da Mitra, Évora, Portugal
| | - Jonathan D. Eisenback
- School of Plant Environmental Science, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Kathryn Kamo
- Floral and Nursery Plants Research Unit, United States of National Arboretum, United States Department of Agriculture, Beltsville, Maryland, United States of America
| | - Paulo Vieira
- Molecular Plant Pathology Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland, United States of America
- School of Plant Environmental Science, Virginia Tech, Blacksburg, Virginia, United States of America
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The pectinases from Sphenophorus levis: Potential for biotechnological applications. Int J Biol Macromol 2018; 112:499-508. [DOI: 10.1016/j.ijbiomac.2018.01.172] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 12/16/2022]
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8
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Biochemical and biophysical characterization of novel GH10 xylanase prospected from a sugar cane bagasse compost-derived microbial consortia. Int J Biol Macromol 2018; 109:560-568. [DOI: 10.1016/j.ijbiomac.2017.12.099] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 12/17/2017] [Accepted: 12/19/2017] [Indexed: 11/17/2022]
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9
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Antony B, Johny J, Aldosari SA, Abdelazim MM. Identification and expression profiling of novel plant cell wall degrading enzymes from a destructive pest of palm trees, Rhynchophorus ferrugineus. INSECT MOLECULAR BIOLOGY 2017; 26:469-484. [PMID: 28556365 DOI: 10.1111/imb.12314] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Plant cell wall degrading enzymes (PCWDEs) from insects were recently identified as a multigene family of proteins that consist primarily of glycoside hydrolases (GHs) and carbohydrate esterases (CEs) and play essential roles in the degradation of the cellulose/hemicellulose/pectin network in the invaded host plant. Here we applied transcriptomic and degenerate PCR approaches to identify the PCWDEs from a destructive pest of palm trees, Rhynchophorus ferrugineus, followed by a gut-specific and stage-specific differential expression analysis. We identified a total of 27 transcripts encoding GH family members and three transcripts of the CE family with cellulase, hemicellulase and pectinase activities. We also identified two GH9 candidates, which have not previously been reported from Curculionidae. The gut-specific quantitative expression analysis identified key cellulases, hemicellulases and pectinases from R. ferrugineus. The expression analysis revealed a pectin methylesterase, RferCE8u02, and a cellulase, GH45c34485, which showed the highest gut enriched expression. Comparison of PCWDE expression patterns revealed that cellulases and pectinases are significantly upregulated in the adult stages, and we observed specific high expression of the hemicellulase RferGH16c4170. Overall, our study revealed the potential of PCWDEs from R. ferrugineus, which may be useful in biotechnological applications and may represent new tools in R. ferrugineus pest management strategies.
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Affiliation(s)
- B Antony
- Department of Plant Protection, Chair of Date Palm Research, College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia
| | - J Johny
- Department of Plant Protection, Chair of Date Palm Research, College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia
| | - S A Aldosari
- Department of Plant Protection, Chair of Date Palm Research, College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia
| | - M M Abdelazim
- Department of Plant Protection, Chair of Date Palm Research, College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia
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10
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Schneider VK, Soares-Costa A, Chakravarthi M, Ribeiro C, Chabregas SM, Falco MC, Henrique-Silva F. Transgenic sugarcane overexpressing CaneCPI-1 negatively affects the growth and development of the sugarcane weevil Sphenophorus levis. PLANT CELL REPORTS 2017; 36:193-201. [PMID: 27837261 DOI: 10.1007/s00299-016-2071-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/03/2016] [Indexed: 05/26/2023]
Abstract
Transgenic sugarcane expressing CaneCPI-1 exhibits resistance to Sphenophorus levis larvae. Transgenic plants have widely been used to improve resistance against insect attack. Sugarcane is an economically important crop; however, great losses are caused by insect attack. Sphenophorus levis is a sugarcane weevil that digs tunnels in the stem base, leading to the destruction of the crop. This insect is controlled inefficiently by chemical insecticides. Transgenic plants expressing peptidase inhibitors represent an important strategy for impairing insect growth and development. Knowledge of the major peptidase group present in the insect gut is critical when choosing the most effective inhibitor. S. levis larvae use cysteine peptidases as their major digestive enzymes, primarily cathepsin L-like activity. In this study, we developed transgenic sugarcane plants that overexpress sugarcane cysteine peptidase inhibitor 1 (CaneCPI-1) and assessed their potential through feeding bioassays with S. levis larvae. Cystatin overexpression in the transgenic plants was evaluated using semi-quantitative RT-PCR, RT-qPCR, and immunoblot assays. A 50% reduction of the average weight was observed in larvae that fed on transgenic plants in comparison to larvae that fed on non-transgenic plants. In addition, transgenic sugarcane exhibited less damage caused by larval attack than the controls. Our results suggest that the overexpression of CaneCPI-1 in sugarcane is a promising strategy for improving resistance against this insect.
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Affiliation(s)
- Vanessa Karine Schneider
- Laboratory of Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washigton Luis, Km 235, São Carlos, SP, 13565-905, Brazil
| | - Andrea Soares-Costa
- Laboratory of Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washigton Luis, Km 235, São Carlos, SP, 13565-905, Brazil
| | - Mohan Chakravarthi
- Laboratory of Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washigton Luis, Km 235, São Carlos, SP, 13565-905, Brazil
| | - Carolina Ribeiro
- Laboratory of Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washigton Luis, Km 235, São Carlos, SP, 13565-905, Brazil
| | - Sabrina Moutinho Chabregas
- Centro de Tecnologia Canavieira, Fazenda Santo Antônio, s/n, cp. 162, Piracicaba, SP, CEP 13400-970, Brazil
| | - Maria Cristina Falco
- Centro de Tecnologia Canavieira, Fazenda Santo Antônio, s/n, cp. 162, Piracicaba, SP, CEP 13400-970, Brazil
| | - Flavio Henrique-Silva
- Laboratory of Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washigton Luis, Km 235, São Carlos, SP, 13565-905, Brazil.
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Wybouw N, Pauchet Y, Heckel DG, Van Leeuwen T. Horizontal Gene Transfer Contributes to the Evolution of Arthropod Herbivory. Genome Biol Evol 2016; 8:1785-801. [PMID: 27307274 PMCID: PMC4943190 DOI: 10.1093/gbe/evw119] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2016] [Indexed: 01/07/2023] Open
Abstract
Within animals, evolutionary transition toward herbivory is severely limited by the hostile characteristics of plants. Arthropods have nonetheless counteracted many nutritional and defensive barriers imposed by plants and are currently considered as the most successful animal herbivores in terrestrial ecosystems. We gather a body of evidence showing that genomes of various plant feeding insects and mites possess genes whose presence can only be explained by horizontal gene transfer (HGT). HGT is the asexual transmission of genetic information between reproductively isolated species. Although HGT is known to have great adaptive significance in prokaryotes, its impact on eukaryotic evolution remains obscure. Here, we show that laterally transferred genes into arthropods underpin many adaptations to phytophagy, including efficient assimilation and detoxification of plant produced metabolites. Horizontally acquired genes and the traits they encode often functionally diversify within arthropod recipients, enabling the colonization of more host plant species and organs. We demonstrate that HGT can drive metazoan evolution by uncovering its prominent role in the adaptations of arthropods to exploit plants.
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Affiliation(s)
- Nicky Wybouw
- Department of Evolutionary Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, the Netherlands
| | - Yannick Pauchet
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - David G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Thomas Van Leeuwen
- Department of Evolutionary Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, the Netherlands Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
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12
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Horizontal Gene Transfer of Pectinases from Bacteria Preceded the Diversification of Stick and Leaf Insects. Sci Rep 2016; 6:26388. [PMID: 27210832 PMCID: PMC4876471 DOI: 10.1038/srep26388] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 04/29/2016] [Indexed: 11/24/2022] Open
Abstract
Genes acquired by horizontal transfer are increasingly being found in animal genomes. Understanding their origin and evolution requires knowledge about the phylogenetic relationships from both source and recipient organisms. We used RNASeq data and respective assembled transcript libraries to trace the evolutionary history of polygalacturonase (pectinase) genes in stick insects (Phasmatodea). By mapping the distribution of pectinase genes on a Polyneoptera phylogeny, we identified the transfer of pectinase genes from known phasmatodean gut microbes into the genome of an early euphasmatodean ancestor that took place between 60 and 100 million years ago. This transfer preceded the rapid diversification of the suborder, enabling symbiont-free pectinase production that would increase the insects’ digestive efficiency and reduce dependence on microbes. Bacteria-to-insect gene transfer was thought to be uncommon, however the increasing availability of large-scale genomic data may change this prevailing notion.
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Kirsch R, Heckel DG, Pauchet Y. How the rice weevil breaks down the pectin network: Enzymatic synergism and sub-functionalization. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 71:72-82. [PMID: 26899322 DOI: 10.1016/j.ibmb.2016.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 02/12/2016] [Accepted: 02/14/2016] [Indexed: 05/19/2023]
Abstract
Pectin is the most complex polysaccharide in nature and highly abundant in plant cell walls and middle lamellae, where it functions in plant growth and development. Phytopathogens utilize plant pectin as an energy source through enzyme-mediated degradation. These pectolytic enzymes include polygalacturonases (PGs) of the GH28 family and pectin methylesterases (PMEs) of the CE8 family. Recently, PGs were also identified in herbivorous insects of the distantly related plant bug, stick insect and Phytophaga beetle lineages. Unlike all other insects, weevils possess PMEs in addition to PGs. To investigate pectin digestion in insects and the role of PMEs in weevils, all PME and PG family members of the rice weevil Sitophilus oryzae were heterologously expressed and functionally characterized. Enzymatically active and inactive PG and PME family members were identified. The loss of activity can be explained by a lack of substrate binding correlating with substitutions of functionally important amino acid residues. We found subfunctionalization in both enzyme families, supported by expression pattern and substrate specificities as well as evidence for synergistic pectin breakdown. Our data suggest that the rice weevil might be able to use pectin as an energy source, and illustrates the potential of both PG and PME enzyme families to functionally diversify after horizontal gene transfer.
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Affiliation(s)
- Roy Kirsch
- Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, Jena, 07745, Germany.
| | - David G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, Jena, 07745, Germany
| | - Yannick Pauchet
- Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, Jena, 07745, Germany.
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