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Zhou L, Meng G, Zhu L, Ma L, Chen K. Insect Antimicrobial Peptides as Guardians of Immunity and Beyond: A Review. Int J Mol Sci 2024; 25:3835. [PMID: 38612644 PMCID: PMC11011964 DOI: 10.3390/ijms25073835] [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: 01/19/2024] [Revised: 02/29/2024] [Accepted: 03/26/2024] [Indexed: 04/14/2024] Open
Abstract
Antimicrobial peptides (AMPs), as immune effectors synthesized by a variety of organisms, not only constitute a robust defense mechanism against a broad spectrum of pathogens in the host but also show promising applications as effective antimicrobial agents. Notably, insects are significant reservoirs of natural AMPs. However, the complex array of variations in types, quantities, antimicrobial activities, and production pathways of AMPs, as well as evolution of AMPs across insect species, presents a significant challenge for immunity system understanding and AMP applications. This review covers insect AMP discoveries, classification, common properties, and mechanisms of action. Additionally, the types, quantities, and activities of immune-related AMPs in each model insect are also summarized. We conducted the first comprehensive investigation into the diversity, distribution, and evolution of 20 types of AMPs in model insects, employing phylogenetic analysis to describe their evolutionary relationships and shed light on conserved and distinctive AMP families. Furthermore, we summarize the regulatory pathways of AMP production through classical signaling pathways and additional pathways associated with Nitric Oxide, insulin-like signaling, and hormones. This review advances our understanding of AMPs as guardians in insect immunity systems and unlocks a gateway to insect AMP resources, facilitating the use of AMPs to address food safety concerns.
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Affiliation(s)
- Lizhen Zhou
- Department of Plant Protection, College of Plant Protection, Yangzhou University, Yangzhou 225009, China;
- Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling 712100, China
| | - Guanliang Meng
- Zoological Research Museum Alexander Koenig, Leibniz Institute for the Analysis of Biodiversity Change, 53113 Bonn, Germany;
| | - Ling Zhu
- School of Food Science and Technology, Jiangnan University, Wuxi 214122, China;
| | - Li Ma
- College of Plant Protection, Shanxi Agricultural University, Taigu 030810, China
| | - Kangkang Chen
- Department of Plant Protection, College of Plant Protection, Yangzhou University, Yangzhou 225009, China;
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2
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Fu Q, Cao D, Sun J, Liu X, Li H, Shu C, Liu R. Prediction and bioactivity of small-molecule antimicrobial peptides from Protaetia brevitarsis Lewis larvae. Front Microbiol 2023; 14:1124672. [PMID: 37007486 PMCID: PMC10060639 DOI: 10.3389/fmicb.2023.1124672] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/02/2023] [Indexed: 03/18/2023] Open
Abstract
Antimicrobial peptides (AMPs) are widely recognized as promising natural antimicrobial agents. Insects, as the group of animals with the largest population, have great potential as a source of AMPs. Thus, it is worthwhile to investigate potential novel AMPs from Protaetia brevitarsis Lewis larvae, which is a saprophagous pest prevalent in China. In this study, comparing the whole-genome sequence of Protaetia brevitarsis Lewis larvae with the Antimicrobial Peptide Database (APD3) led to the identification of nine peptide templates that were potentially AMPs. Next, based on the peptide templates, 16 truncated sequences were predicted to the AMPs by bioinformatics software and then underwent structural and physicochemical property analysis. Thereafter, candidate small-molecule AMPs were artificially synthesized and their minimal inhibitory concentration (MIC) values were assessed. A candidate peptide, designated FD10, exhibited strong antimicrobial activity against both bacteria and fungi comprising Escherichia coli (MIC: 8 μg/mL), Pseudomonas aeruginosa (MIC: 8 μg/mL), Bacillus thuringiensis (MIC: 8 μg/mL), Staphylococcus aureus (MIC: 16 μg/mL), and Candida albicans (MIC: 16 μg/mL). Additionally, two other candidate peptides, designated FD12 and FD15, exhibited antimicrobial activity against both E. coli (MIC: both 32 μg/mL) and S. aureus (MIC: both 16 μg/mL). Moreover, FD10, FD12, and FD15 killed almost all E. coli and S. aureus cells within 1 h, and the hemolytic effect of FD10 (0.31%) and FD12 (0.40%) was lower than that of ampicillin (0.52%). These findings indicate that FD12, FD15, and especially FD10 are promising AMPs for therapeutic application. This study promoted the development of antibacterial drugs and provided a theoretical basis for promoting the practical application of antimicrobial peptides in the Protaetia brevitarsis Lewis larvae.
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Affiliation(s)
- Qian Fu
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Dengtian Cao
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Jing Sun
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Xinbo Liu
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Haitao Li
- College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Changlong Shu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- *Correspondence: Changlong Shu,
| | - Rongmei Liu
- College of Life Sciences, Northeast Agricultural University, Harbin, China
- Rongmei Liu,
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3
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Feng L, Wang Y, Yang J, Sun YF, Li YW, Ye ZH, Lin HB, Yang K. Overview of the preparation method, structure and function, and application of natural peptides and polypeptides. Biomed Pharmacother 2022; 153:113493. [DOI: 10.1016/j.biopha.2022.113493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/26/2022] [Accepted: 07/27/2022] [Indexed: 02/06/2023] Open
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Li J, Chen C, Zha X. Midgut and Head Transcriptomic Analysis of Silkworms Reveals the Physiological Effects of Artificial Diets. INSECTS 2022; 13:insects13030291. [PMID: 35323589 PMCID: PMC8948783 DOI: 10.3390/insects13030291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/06/2022] [Accepted: 03/11/2022] [Indexed: 02/04/2023]
Abstract
Silkworms, a model lepidopteran insect, have a very simple diet. Artificial diets as an alternative nutrient source for silkworms are gradually being developed. To understand the effects of various nutrients on the growth and development of silkworms, we studied the transcriptomic differences in the midgut and head tissues of male and female silkworms fed either fresh mulberry leaves or artificial diets. In the artificial diet group, compared with the control group (fed mulberry leaves), 923 and 619 differentially expressed genes (DEGs) were identified from the midgut, and 2969 and 3427 DEGs were identified from the head, in female and male silkworms. According to our analysis, the DEGs were mainly involved in the digestion and absorption of nutrients and silkworm innate immunity. These experimental results provide insights into the effects of different foods, such as artificial diets or fresh mulberry leaves, on silkworms.
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Affiliation(s)
- Juan Li
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (J.L.); (C.C.)
- School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Chunbing Chen
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (J.L.); (C.C.)
| | - Xingfu Zha
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China; (J.L.); (C.C.)
- Correspondence: ; Tel.: +86-023-68251573
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Liu FF, Ding C, Yang LL, Li H, Rao XJ. Identification and analysis of two lebocins in the oriental armyworm Mythimna separata. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 116:103962. [PMID: 33301794 DOI: 10.1016/j.dci.2020.103962] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/04/2020] [Accepted: 12/04/2020] [Indexed: 06/12/2023]
Abstract
The insect immune system can produce defensive molecules, such as antimicrobial peptides (AMPs), to eliminate invading pathogens. Here, we report the identification of two cDNAs (MseLeb1, MseLeb2) that encode lepidopteral lebocin preproproteins in the oriental armyworm, Mythimna separata. Their open reading frames are 483/492 bp that encode 161/164 aa peptides. MseLeb1 is mainly expressed in the fat body and epidermis, while MseLeb2 is mainly expressed in the fat body, Malpighian tube, and epidermis. They were significantly induced by Escherichia coli, Staphylococcus aureus, and Beauveria bassiana in hemocytes. The preproproteins can be processed after RXXR motifs into mature peptides. Multiple sequence alignment indicates that MseLeb1 (18-42, 121-161) are potentially active peptides. Five peptides were synthesized for analyses: 18-42, 121-161, 121-154, 121-151, 121-146. Synthetic peptides showed agglutinating activity, but no hemolytic activity. Bacterial growth assay, colony formation assay, and electron microscopy revealed that synthetic peptides can inhibit bacterial growth and disrupt bacterial cell wall. B. bassiana conidia and blastospores were lysed by synthetic peptides. These results indicate that MseLeb1 and MseLeb2 are immune responsive lebocins, and the mature peptides have antibacterial and antifungal activities.
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Affiliation(s)
- Fang-Fang Liu
- Anhui Province Key Laboratory of Integrated Pest Management on Crops, Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, School of Plant Protection, Anhui Agricultural University, Hefei, 230036, China
| | - Chen Ding
- Anhui Province Key Laboratory of Integrated Pest Management on Crops, Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, School of Plant Protection, Anhui Agricultural University, Hefei, 230036, China
| | - Li-Ling Yang
- Anhui Province Key Laboratory of Integrated Pest Management on Crops, Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, School of Plant Protection, Anhui Agricultural University, Hefei, 230036, China
| | - Hao Li
- Anhui Province Key Laboratory of Integrated Pest Management on Crops, Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, School of Plant Protection, Anhui Agricultural University, Hefei, 230036, China
| | - Xiang-Jun Rao
- Anhui Province Key Laboratory of Integrated Pest Management on Crops, Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, School of Plant Protection, Anhui Agricultural University, Hefei, 230036, China.
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Yang LL, Zhan MY, Zhuo YL, Dang XL, Li MY, Xu Y, Zhou XH, Yu XQ, Rao XJ. Characterization of the active fragments of Spodoptera litura Lebocin-1. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2020; 103:e21626. [PMID: 31562754 DOI: 10.1002/arch.21626] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/09/2019] [Accepted: 09/14/2019] [Indexed: 06/10/2023]
Abstract
Insects can produce various antimicrobial peptides (AMPs) upon immune stimulation. One class of AMPs are characterized by their high proline content in certain fragments. They are generally called proline-rich antimicrobial peptides (PrAMPs). We previously reported the characterization of Spodoptera litura lebocin-1 (SlLeb-1), a PrAMP proprotein. Preliminary studies with synthetic polypeptides showed that among the four deductive active fragments, the C-terminal fragment SlLeb-1 (124-158) showed strong antibacterial activities. Here, we further characterized the antibacterial and antifungal activities of 124-158 and its four subfragments: 124-155, 124-149, 127-158, and 135-158. Only 124-158 and 127-158 could agglutinate bacteria, while 124-158 and four subfragments all could agglutinate Beauveria bassiana spores. Confocal microscopy showed that fluorescent peptides were located on the microbial surface. Fragment 135-158 lost activity completely against Escherichia coli and Staphylococcus aureus, and partially against Bacillus subtilis. Only 124-149 showed low activity against Serratia marcescens. Negative staining, transmission, and scanning electron microscopy of 124-158 treated bacteria showed different morphologies. Flow cytometry analysis of S. aureus showed that 124-158 and four subfragments changed bacterial subpopulations and caused an increase of DNA content. These results indicate that active fragments of SlLeb-1 may have diverse antimicrobial effects against different microbes. This study may provide an insight into the development of novel antimicrobial agents.
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Affiliation(s)
- Li-Ling Yang
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, China
| | - Ming-Yue Zhan
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, China
| | - Yu-Li Zhuo
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, China
| | - Xiang-Li Dang
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, China
| | - Mao-Ye Li
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, China
| | - Yang Xu
- Biotechnology Center, Anhui Agricultural University, Hefei, Anhui, China
| | - Xiu-Hong Zhou
- Biotechnology Center, Anhui Agricultural University, Hefei, Anhui, China
| | - Xiao-Qiang Yu
- Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Xiang-Jun Rao
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, China
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7
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Zhang J, Li Q, Wei G, Wang L, Qian C, Sun Y, Tian J, Zhu B, Liu C. Identification and function of a lebocin-like gene from the Chinese oak silkworm, Antheraea pernyi. J Invertebr Pathol 2019; 166:107207. [DOI: 10.1016/j.jip.2019.107207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 05/27/2019] [Accepted: 05/28/2019] [Indexed: 11/26/2022]
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Díaz-Garrido P, Sepúlveda-Robles O, Martínez-Martínez I, Espinoza B. Variability of defensin genes from a Mexican endemic Triatominae: Triatoma (Meccus) pallidipennis (Hemiptera: Reduviidae). Biosci Rep 2018; 38:BSR20180988. [PMID: 30181380 PMCID: PMC6165835 DOI: 10.1042/bsr20180988] [Citation(s) in RCA: 9] [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: 06/23/2018] [Revised: 08/16/2018] [Accepted: 08/30/2018] [Indexed: 01/19/2023] Open
Abstract
Chagas disease remains a serious health problem for countries where the most common mode of transmission is infection contracted from the feces of a Triatominae insect vector. In México, 32 species of Triatoma have been identified; amongst them, Triatoma (Meccus) pallidipennis is an endemic species reported to have high percentages of infection with T. cruzi Defensins, cysteine-rich cationic peptides, are a family of antimicrobial peptides (AMPs); the synthesis of these molecules is crucial for insect's immune defense. In the present study, the genes encoding defensins in T. pallidipennis were sequenced with the purpose of identifying the variability of these genes in a Mexican vector of T. cruzi We found 12 different genes encoding three mature peptides, all of which had the typical folding of a functional insect defensin. In this work two Defensins type 1 and one type 4 were identified. The pro-peptide domain was highly variable and the mature peptide was not. This is the first report focus on variability of defensins from an epidemiologically important Triatoma in Mexico.
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Affiliation(s)
- Paulina Díaz-Garrido
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, UNAM 04510, Ciudad de México, México
| | - Omar Sepúlveda-Robles
- Catedrático CONACyT - Unidad de Investigación Médica en Epidemiología Clínica UMAE-Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México
| | - Ignacio Martínez-Martínez
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, UNAM 04510, Ciudad de México, México
| | - Bertha Espinoza
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, UNAM 04510, Ciudad de México, México
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Yang LL, Zhan MY, Zhuo YL, Pan YM, Xu Y, Zhou XH, Yang PJ, Liu HL, Liang ZH, Huang XD, Yu XQ, Rao XJ. Antimicrobial activities of a proline-rich proprotein from Spodoptera litura. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 87:137-146. [PMID: 29935286 DOI: 10.1016/j.dci.2018.06.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 06/19/2018] [Accepted: 06/20/2018] [Indexed: 06/08/2023]
Abstract
Antimicrobial peptides (AMPs) are produced by the stimulated humoral immune system. Most mature AMPs contain less than 50 amino acid residues. Some of them are generated from proproteins upon microbial challenges. Here, we report the antimicrobial activities of a proline-rich proprotein, named SlLebocin1 (SlLeb1), from the tobacco cutworm Spodoptera litura. SlLebocin1 cDNA contains a 477-bp open reading frame (ORF). It is mainly expressed in hemocytes and the midgut in naïve larvae. The transcript level was significantly induced in hemocytes but repressed in the midgut and fat body by bacterial challenges. The proprotein contains 158 amino acids with 3 RXXR motifs that are characteristic of some Lepidopteral lebocin proproteins. Four peptides corresponding to the predicted processed fragments were synthesized chemically, and their antimicrobial activities against two Gram-negative and two Gram-positive bacterial strains were analyzed. The peptides showed differential antimicrobial activities. For Escherichia coli and Bacillus subtilis, only the C-terminal fragment (124-158) showed strong inhibitory effects. For Staphylococcus aureus, all peptides showed partial inhibitions. None of them inhibited Serratia marcescens. Bacterial morphologies were examined by the scanning electron microscopy and confocal laser scanning microscopy. The antimicrobial peptides either disrupted cellular membrane or inhibited cell division and caused elongated/enlarged morphologies. The results may provide ideas for designing novel antibiotics.
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Affiliation(s)
- Li-Ling Yang
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Ming-Yue Zhan
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Yu-Li Zhuo
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Yue-Min Pan
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Yang Xu
- Biotechnology Center, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Xiu-Hong Zhou
- Biotechnology Center, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Pei-Jin Yang
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Hong-Li Liu
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Zi-Hao Liang
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Xiao-Dan Huang
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China
| | - Xiao-Qiang Yu
- School of Life Sciences, Central China Normal University, Wuhan, 430079, China
| | - Xiang-Jun Rao
- School of Plant Protection, Anhui Agricultural University, Hefei, Anhui, 230036, China.
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Kozic M, Fox SJ, Thomas JM, Verma CS, Rigden DJ. Large scale ab initio modeling of structurally uncharacterized antimicrobial peptides reveals known and novel folds. Proteins 2018; 86:548-565. [DOI: 10.1002/prot.25473] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/16/2018] [Accepted: 01/29/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Mara Kozic
- Institute of Integrative Biology, University of Liverpool; Liverpool L69 7ZB U.K
- Agency for Science, Technology and Research (A*STAR), Bioinformatics Institute; Singapore
| | - Stephen J. Fox
- Agency for Science, Technology and Research (A*STAR), Bioinformatics Institute; Singapore
| | - Jens M. Thomas
- Institute of Integrative Biology, University of Liverpool; Liverpool L69 7ZB U.K
| | - Chandra S. Verma
- Agency for Science, Technology and Research (A*STAR), Bioinformatics Institute; Singapore
- Department of Biological Sciences; National University of Singapore; Singapore
- School of Biological Sciences; Nanyang Technological University; Singapore
| | - Daniel J. Rigden
- Institute of Integrative Biology, University of Liverpool; Liverpool L69 7ZB U.K
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Molecular Cloning, Bioinformatic Analysis, and Expression of Bombyx mori Lebocin 5 Gene Related to Beauveria bassiana Infection. BIOMED RESEARCH INTERNATIONAL 2017; 2017:9390803. [PMID: 28194425 PMCID: PMC5282435 DOI: 10.1155/2017/9390803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 11/21/2016] [Accepted: 12/19/2016] [Indexed: 11/22/2022]
Abstract
A full-length cDNA of lebocin 5 (BmLeb5) was first cloned from silkworm, Bombyx mori, by rapid amplification of cDNA ends. The BmLeb5 gene is 808 bp in length and the open reading frame encodes a 179-amino acid hydroxyproline-rich peptide. Bioinformatic analysis results showed that BmLeb5 owns an O-glycosylation site and four RXXR motifs as other lebocins. Sequence similarity and phylogenic analysis results indicated that lebocins form a multiple gene family in silkworm as cecropins. Quantitative real-time PCR analysis revealed that BmLeb5 was highest expressed in the fat body. In the silkworm larvae infected by Beauveria bassiana, the expression level of BmLeb5 was upregulated in the fat body and hemolymph which are the most important immune tissues in silkworm. The recombinant protein of BmLeb5 was for the first time successfully expressed with prokaryotic expression system and purified. There are no reports so far that the expression of lebocins could be induced by entomopathogenic fungus. Our study suggested that BmLeb5 might play an important role in the immune response of silkworm to defend B. bassiana infection. The results also provided helpful information for further studying the lebocin family functioned in antifungal immune response in the silkworm.
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Al Souhail Q, Hiromasa Y, Rahnamaeian M, Giraldo MC, Takahashi D, Valent B, Vilcinskas A, Kanost MR. Characterization and regulation of expression of an antifungal peptide from hemolymph of an insect, Manduca sexta. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 61:258-68. [PMID: 26976231 PMCID: PMC4866881 DOI: 10.1016/j.dci.2016.03.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 03/08/2016] [Accepted: 03/08/2016] [Indexed: 05/07/2023]
Abstract
Insects secrete antimicrobial peptides as part of the innate immune response. Most antimicrobial peptides from insects have antibacterial but not antifungal activity. We have characterized an antifungal peptide, diapausin-1 from hemolymph of a lepidopteran insect, Manduca sexta (tobacco hornworm). Diapausin-1 was isolated by size exclusion chromatography from hemolymph plasma of larvae that were previously injected with a yeast, Saccharomyces cerevisiae. Fractions containing activity against S. cerevisiae were analyzed by SDS-PAGE and MALDI-TOF MS/MS and found to contain a 45-residue peptide that was encoded by sequences identified in M. sexta transcriptome and genome databases. A cDNA for diapausin-1 was cloned from cDNA prepared from fat body RNA. Diapausin-1 is a member of the diapausin family of peptides, which includes members known to have antifungal activity. The M. sexta genome contains 14 genes with high similarity to diapausin-1, each with 6 conserved Cys residues. Diapausin-1 was produced as a recombinant protein in Escherichia coli. Purified recombinant diapausin-1 was active against S. cerevisiae, with IC50 of 12 μM, but had no detectable activity against bacteria. Spores of some plant fungal pathogens treated with diapausin-1 had curled germination tubes or reduced and branched hyphal growth. Diapausin-1 mRNA level in fat body strongly increased after larvae were injected with yeast or with Micrococcus luteus. In addition, diapausin-1 mRNA levels increased in midgut and fat body at the wandering larval stage prior to pupation, suggesting developmental regulation of the gene. Our results indicate that synthesis of diapausin-1 is part of an antifungal innate immune response to infection in M. sexta.
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Affiliation(s)
- Qasim Al Souhail
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Yasuaki Hiromasa
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Mohammad Rahnamaeian
- LOEWE Center for Insect Biotechnology and Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Giessen Winchesterstrasse 2, 35394 Giessen, Germany
| | - Martha C Giraldo
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA
| | - Daisuke Takahashi
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Barbara Valent
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA
| | - Andreas Vilcinskas
- LOEWE Center for Insect Biotechnology and Bioresources, Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Giessen Winchesterstrasse 2, 35394 Giessen, Germany; Institute for Insect Biotechnology, Justus-Liebig-University of Giessen, Heinrich-Buff-Ring 26-32, 39592 Giessen, Germany
| | - Michael R Kanost
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA.
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He Y, Cao X, Zhang S, Rogers J, Hartson S, Jiang H. Changes in the Plasma Proteome of Manduca sexta Larvae in Relation to the Transcriptome Variations after an Immune Challenge: Evidence for High Molecular Weight Immune Complex Formation. Mol Cell Proteomics 2016; 15:1176-87. [PMID: 26811355 DOI: 10.1074/mcp.m115.054296] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Indexed: 11/06/2022] Open
Abstract
Manduca sextais a lepidopteran model widely used to study insect physiological processes, including innate immunity. In this study, we explored the proteomes of cell-free hemolymph from larvae injected with a sterile buffer (C for control) or a mixture of bacteria (I for induced). Of the 654 proteins identified, 70 showed 1.67 to >200-fold abundance increases after the immune challenge; 51 decreased to 0-60% of the control levels. While there was no strong parallel between plasma protein levels and their transcript levels in hemocytes or fat body, the mRNA level changes (i.e.I/C ratios of normalized read numbers) in the tissues concurred with their protein level changes (i.e.I/C ratios of normalized spectral counts) with correlation coefficients of 0.44 and 0.57, respectively. Better correlations support that fat body contributes a more significant portion of the plasma proteins involved in various aspects of innate immunity. Consistently, ratios of mRNA and protein levels were better correlated for immunity-related proteins than unrelated ones. There is a set of proteins whose apparent molecular masses differ considerably from the calculatedMr's, suggestive of posttranslational modifications. In addition, some lowMrproteins were detected in the range of 80 to >300 kDa on a reducing SDS-polyacrylamide gel, indicating the existence of highMrcovalent complexes. We identified 30 serine proteases and their homologs, 11 of which are known members of an extracellular immune signaling network. Along with our quantitative transcriptome data, the protein identification, inducibility, and association provide leads toward a focused exploration of humoral immunity inM. sexta.
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Affiliation(s)
- Yan He
- From the ‡Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Xiaolong Cao
- From the ‡Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078; §Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078
| | - Shuguang Zhang
- From the ‡Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Janet Rogers
- §Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078
| | - Steve Hartson
- §Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078
| | - Haobo Jiang
- From the ‡Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078;
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14
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Gerdol M, Puillandre N, De Moro G, Guarnaccia C, Lucafò M, Benincasa M, Zlatev V, Manfrin C, Torboli V, Giulianini PG, Sava G, Venier P, Pallavicini A. Identification and Characterization of a Novel Family of Cysteine-Rich Peptides (MgCRP-I) from Mytilus galloprovincialis. Genome Biol Evol 2015. [PMID: 26201648 PMCID: PMC4558851 DOI: 10.1093/gbe/evv133] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We report the identification of a novel gene family (named MgCRP-I) encoding short secreted cysteine-rich peptides in the Mediterranean mussel Mytilus galloprovincialis. These peptides display a highly conserved pre-pro region and a hypervariable mature peptide comprising six invariant cysteine residues arranged in three intramolecular disulfide bridges. Although their cysteine pattern is similar to cysteines-rich neurotoxic peptides of distantly related protostomes such as cone snails and arachnids, the different organization of the disulfide bridges observed in synthetic peptides and phylogenetic analyses revealed MgCRP-I as a novel protein family. Genome- and transcriptome-wide searches for orthologous sequences in other bivalve species indicated the unique presence of this gene family in Mytilus spp. Like many antimicrobial peptides and neurotoxins, MgCRP-I peptides are produced as pre-propeptides, usually have a net positive charge and likely derive from similar evolutionary mechanisms, that is, gene duplication and positive selection within the mature peptide region; however, synthetic MgCRP-I peptides did not display significant toxicity in cultured mammalian cells, insecticidal, antimicrobial, or antifungal activities. The functional role of MgCRP-I peptides in mussel physiology still remains puzzling.
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Affiliation(s)
- Marco Gerdol
- Department of Life Sciences, University of Trieste, Italy
| | - Nicolas Puillandre
- Muséum National d'Histoire Naturelle, Département Systématique et Evolution, ISyEB Institut (UMR 7205 CNRS/UPMC/MNHN/EPHE), Paris, France
| | | | - Corrado Guarnaccia
- Protein Structure and Bioinformatics Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | | | | | - Ventislav Zlatev
- Protein Structure and Bioinformatics Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Chiara Manfrin
- Department of Life Sciences, University of Trieste, Italy
| | | | | | - Gianni Sava
- Department of Life Sciences, University of Trieste, Italy
| | - Paola Venier
- Department of Biology, University of Padova, Italy
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15
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Molecular cloning and characterization of gloverin from the diamondback moth, Plutella xylostella L. and its interaction with bacterial membrane. World J Microbiol Biotechnol 2015; 31:1529-41. [DOI: 10.1007/s11274-015-1901-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 07/09/2015] [Indexed: 10/23/2022]
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16
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He Y, Cao X, Li K, Hu Y, Chen YR, Blissard G, Kanost MR, Jiang H. A genome-wide analysis of antimicrobial effector genes and their transcription patterns in Manduca sexta. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 62:23-37. [PMID: 25662101 PMCID: PMC4476920 DOI: 10.1016/j.ibmb.2015.01.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 01/13/2015] [Accepted: 01/23/2015] [Indexed: 05/09/2023]
Abstract
Antimicrobial proteins/peptides (AMPs) are effectors of innate immune systems against pathogen infection in multicellular organisms. Over half of the AMPs reported so far come from insects, and these effectors act in concert to suppress or kill bacteria, fungi, viruses, and parasites. In this work, we have identified 86 AMP genes in the Manduca sexta genome, most of which seem likely to be functional. They encode 15 cecropins, 6 moricins, 6 defensins, 3 gallerimycins, 4 X-tox splicing variants, 14 diapausins, 15 whey acidic protein homologs, 11 attacins, 1 gloverin, 4 lebocins, 6 lysozyme-related proteins, and 4 transferrins. Some of these genes (e.g. attacins, cecropins) constitute large clusters, likely arising after rounds of gene duplication. We compared the amino acid sequences of M. sexta AMPs with their homologs in other insects to reveal conserved structural features and phylogenetic relationships. Expression data showed that many of them are synthesized in fat body and midgut during the larval-pupal molt. Certain genes contain one or more predicted κB binding sites and other regulatory elements in their promoter regions, which may account for the dramatic mRNA level increases in fat body and hemocytes after an immune challenge. Consistent with these strong mRNA increases, many AMPs become highly abundant in the larval plasma at 24 h after the challenge, as demonstrated in our previous peptidomic study. Taken together, these data suggest the existence of a large repertoire of AMPs in M. sexta, whose expression is up-regulated via immune signaling pathways to fight off invading pathogens in a coordinated manner.
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Affiliation(s)
- Yan He
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Xiaolong Cao
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Kai Li
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA; Institute of Biological Sciences, Donghua University, Songjiang, Shanghai 310029, China
| | - Yingxia Hu
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Yun-ru Chen
- Boyce Thompson Institute, Cornell University, Ithaca, NY 14853, USA
| | - Gary Blissard
- Boyce Thompson Institute, Cornell University, Ithaca, NY 14853, USA
| | - Michael R Kanost
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
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17
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Crava CM, Jakubowska AK, Escriche B, Herrero S, Bel Y. Dissimilar Regulation of Antimicrobial Proteins in the Midgut of Spodoptera exigua Larvae Challenged with Bacillus thuringiensis Toxins or Baculovirus. PLoS One 2015; 10:e0125991. [PMID: 25993013 PMCID: PMC4436361 DOI: 10.1371/journal.pone.0125991] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/27/2015] [Indexed: 01/24/2023] Open
Abstract
Antimicrobial peptides (AMPs) and lysozymes are the main effectors of the insect immune system, and they are involved in both local and systemic responses. Among local responses, midgut immune reaction plays an important role in fighting pathogens that reach the insect body through the oral route, as do many microorganisms used in pest control. Under this point of view, understanding how insects defend themselves locally during the first phases of infections caused by food-borne pathogens is important to further improve microbial control strategies. In the present study, we analyzed the transcriptional response of AMPs and lysozymes in the midgut of Spodoptera exigua (Lepidoptera: Noctuidae), a polyphagous pest that is commonly controlled by products based on Bacillus thuringiensis (Bt) or baculovirus. First, we comprehensively characterized the transcripts encoding AMPs and lysozymes expressed in S. exigua larval midgut, identifying 35 transcripts that represent the S. exigua arsenal against microbial infection. Secondly, we analyzed their expression in the midgut after ingestion of sub-lethal doses of two different pore-forming B. thuringiensis toxins, Cry1Ca and Vip3Aa, and the S. exigua nucleopolyhedrovirus (SeMNPV). We observed that both Bt toxins triggered a similar, wide and in some cases high transcriptional activation of genes encoding AMPs and lysozymes, which was not reflected in the activation of the classical systemic immune-marker phenoloxidase in hemolymph. Baculovirus ingestion resulted in the opposed reaction: Almost all transcripts coding for AMPs and lysozymes were down-regulated or not induced 96 hours post infection. Our results shed light on midgut response to different virulence factors or pathogens used nowadays as microbial control agents and point out the importance of the midgut immune response contribution to the larval immunity.
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Affiliation(s)
- Cristina M. Crava
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), University of Valencia, Burjassot, Valencia, Spain
| | - Agata K. Jakubowska
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), University of Valencia, Burjassot, Valencia, Spain
| | - Baltasar Escriche
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), University of Valencia, Burjassot, Valencia, Spain
| | - Salvador Herrero
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), University of Valencia, Burjassot, Valencia, Spain
| | - Yolanda Bel
- Department of Genetics, University of Valencia, Burjassot, Valencia, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), University of Valencia, Burjassot, Valencia, Spain
- * E-mail:
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18
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Yi HY, Chowdhury M, Huang YD, Yu XQ. Insect antimicrobial peptides and their applications. Appl Microbiol Biotechnol 2014; 98:5807-22. [PMID: 24811407 DOI: 10.1007/s00253-014-5792-6] [Citation(s) in RCA: 346] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/21/2014] [Accepted: 04/23/2014] [Indexed: 10/25/2022]
Abstract
Insects are one of the major sources of antimicrobial peptides/proteins (AMPs). Since observation of antimicrobial activity in the hemolymph of pupae from the giant silk moths Samia Cynthia and Hyalophora cecropia in 1974 and purification of first insect AMP (cecropin) from H. cecropia pupae in 1980, over 150 insect AMPs have been purified or identified. Most insect AMPs are small and cationic, and they show activities against bacteria and/or fungi, as well as some parasites and viruses. Insect AMPs can be classified into four families based on their structures or unique sequences: the α-helical peptides (cecropin and moricin), cysteine-rich peptides (insect defensin and drosomycin), proline-rich peptides (apidaecin, drosocin, and lebocin), and glycine-rich peptides/proteins (attacin and gloverin). Among insect AMPs, defensins, cecropins, proline-rich peptides, and attacins are common, while gloverins and moricins have been identified only in Lepidoptera. Most active AMPs are small peptides of 20-50 residues, which are generated from larger inactive precursor proteins or pro-proteins, but gloverins (~14 kDa) and attacins (~20 kDa) are large antimicrobial proteins. In this mini-review, we will discuss current knowledge and recent progress in several classes of insect AMPs, including insect defensins, cecropins, attacins, lebocins and other proline-rich peptides, gloverins, and moricins, with a focus on structural-functional relationships and their potential applications.
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Affiliation(s)
- Hui-Yu Yi
- College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
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19
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Jin F, Sun Q, Xu X, Li L, Gao G, Xu Y, Yu X, Ren S. cDNA cloning and characterization of the antibacterial peptide cecropin 1 from the diamondback moth, Plutella xylostella L. Protein Expr Purif 2012; 85:230-8. [PMID: 22921836 DOI: 10.1016/j.pep.2012.08.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 08/01/2012] [Accepted: 08/08/2012] [Indexed: 10/28/2022]
Abstract
Cecropins are linear cationic antibacterial peptides that have potent activities against microorganisms. In the present study, a 480bp full-length cDNA encoding diamondback moth (Plutella xylostella) cecropin 1 (designated as Px-cec1) was obtained using RT-PCR. A Northern blot analysis showed that the Px-cec1 transcript was predominantly expressed in fat bodies, hemocytes, midgut and epidermis with the highest expression level in fat bodies. The expression of Px-cec1 mRNA in fat bodies was significantly increased 24h after microbial challenge, with the highest induced expression by Staphylococcus aureus. A circular dichroism (CD) analysis revealed that the recombinant Px-cec1 mainly contained α-helixes. Antimicrobial assays demonstrated that recombinant Px-cec1 exhibited a broad spectrum of anti-microbial properties against fungi, Gram-positive and Gram-negative bacteria, but it did not exhibit hemolytic activity against human erythrocytes. Furthermore, Px-cec1 caused significant morphological alterations of S. aureus, as shown by scanning electron microscopy and transmission electron microscopy. These results demonstrated that Px-cec1 exerts its antibacterial activity by acting on the cell membrane to disrupt bacterial cell structures.
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Affiliation(s)
- Fengliang Jin
- College of Natural Resources and Environments, South China Agricultural University, Engineering Research Center of Biological Control, Ministry of Education, Guangzhou, China.
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20
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Rao XJ, Xu XX, Yu XQ. Functional analysis of two lebocin-related proteins from Manduca sexta. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2012; 42:231-9. [PMID: 22198332 PMCID: PMC3288250 DOI: 10.1016/j.ibmb.2011.12.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 05/03/2023]
Abstract
Insects produce a group of antimicrobial peptides (AMPs) in response to microbial infections. Most AMPs are synthesized as inactive precursors/pro-proteins and require proteolytic processing to generate small active peptides. Here we report identification and functional analysis of two lebocin-related proteins (Leb-B and Leb-C) from the tobacco hornworm, Manduca sexta. The mRNA levels of Leb-B and Leb-C increased significantly in larval fat body and hemocytes after injection of Escherichia coli, Micrococcus luteus and Saccharomyces cerevisiae. Western blotting using rabbit polyclonal antibody to Leb-B showed accumulation of large protein(s) and small peptide(s) in larval hemolymph after microbial injection. This result and the presence of RXXR motifs in the deduced amino acid sequences led to our postulation that Leb-B/C may be inactive precursors that are processed in larval hemolymph to generate short active peptides. To test this hypothesis, we expressed and purified full-length and various fragments of Leb-B and Leb-C as thioredoxin (TRX) fusion proteins. We found that fusion proteins could be cleaved by induced larval plasma, and the cleavage sites were determined by protein sequencing. Antibacterial activity of peptide fragments was also verified using synthetic peptides, and active M. sexta lebocin peptides were located at the N-termini of Leb-B/C, which are different from Bombyx mori lebocins 1-4 that are located close to the C-termini. In addition, we found that synthetic Leb-B(22-48) peptide not only had higher antibacterial activity but also caused agglutination of E. coli cells. Our results provide valuable information for studying processing of lebocin precursors in lepidopteran insects.
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Affiliation(s)
| | | | - Xiao-Qiang Yu
- Send correspondence to: Xiao-Qiang Yu, PhD, Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, 5007 Rockhill Road, Kansas City, MO 64110, Telephone: (816)-235-6379, Fax: (816)-235-1503,
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21
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Zhang S, Gunaratna RT, Zhang X, Najar F, Wang Y, Roe B, Jiang H. Pyrosequencing-based expression profiling and identification of differentially regulated genes from Manduca sexta, a lepidopteran model insect. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 41:733-46. [PMID: 21641996 PMCID: PMC3142711 DOI: 10.1016/j.ibmb.2011.05.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/16/2011] [Accepted: 05/19/2011] [Indexed: 05/13/2023]
Abstract
Although Manduca sexta has significantly contributed to our knowledge on a variety of insect physiological processes, the lack of its genome sequence hampers the large-scale gene discovery, transcript profiling, and proteomic analysis in this biochemical model species. Here we report our implementation of the RNA-Seq cDNA sequencing approach based on massively parallel pyrosequencing, which allows us to categorize transcripts based on their relative abundances and to discover process- or tissue-specifically regulated genes simultaneously. We obtained 1,821,652 reads with an average length of 289 bp per read from fat body and hemocytes of naïve and microbe-injected M. sexta larvae. After almost all (92.1%) of these reads were assembled into 19,020 contigs, we identified 528 contigs whose relative abundances increased at least 5- and 8-fold in fat body and hemocytes, respectively, after the microbial challenge. Polypeptides encoded by these contigs include pathogen recognition receptors, extracellular and intracellular signal mediators and regulators, antimicrobial peptides, and proteins with no known sequence but likely participating in defense in novel ways. We also found 250 and 161 contigs that were preferentially expressed in fat body and hemocytes, respectively. Furthermore, we integrated data from our previous study and generated a sequence database to support future gene annotation and proteomic analysis in M. sexta. In summary, we have successfully established a combined approach for gene discovery and expression profiling in organisms lacking known genome sequences.
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Affiliation(s)
- Shuguang Zhang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Ramesh T. Gunaratna
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Xiufeng Zhang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Fares Najar
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Bruce Roe
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
- Send correspondence to: Haobo Jiang, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, Telephone: (405)-744-9400,
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22
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Abstract
Lepidopteran insects provide important model systems for innate immunity of insects, particularly for cell biology of hemocytes and biochemical analyses of plasma proteins. Caterpillars are also among the most serious agricultural pests, and understanding of their immune systems has potential practical significance. An early response to infection in lepidopteran larvae is the activation of hemocyte adhesion, leading to phagocytosis, nodule formation, or encapsulation. Plasmatocytes and granular cells are the hemocyte types involved in these responses. Infectious microorganisms are recognized by binding of hemolymph plasma proteins to microbial surface components. This "pattern recognition" triggers phagocytosis and nodule formation, activation of prophenoloxidase and melanization and the synthesis of antimicrobial proteins that are secreted into the hemolymph. Many hemolymph proteins that function in such innate immune responses of insects were first discovered in lepidopterans. Microbial proteinases and nucleic acids released from lysed host cells may also activate lepidopteran immune responses. Hemolymph antimicrobial peptides and proteins can reach high concentrations and may have activity against a broad spectrum of microorganisms, contributing significantly to clearing of infections. Serine proteinase cascade pathways triggered by microbial components interacting with pattern recognition proteins stimulate activation of the cytokine Spätzle, which initiates the Toll pathway for expression of antimicrobial peptides. A proteinase cascade also results inproteolytic activation of phenoloxidase and production of melanin coatings that trap and kill parasites and pathogens. The proteinases in hemolymph are regulated by specific inhibitors, including members of the serpin superfamily. New developments in lepidopteran functional genomics should lead to much more complete understanding of the immune systems of this insect group.
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