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Miao Z, Xiong C, Wang Y, Shan T, Jiang H. Identification of immunity-related genes distinctly regulated by Manduca sexta Spӓtzle-1/2 and Escherichia coli peptidoglycan. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2024; 168:104108. [PMID: 38552808 PMCID: PMC11443596 DOI: 10.1016/j.ibmb.2024.104108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 03/03/2024] [Accepted: 03/14/2024] [Indexed: 04/08/2024]
Abstract
The immune system of Manduca sexta has been well studied to understand molecular mechanisms of insect antimicrobial responses. While evidence supports the existence of major immune signaling pathways in this species, it is unclear how induced production of defense proteins is specifically regulated by the Toll and Imd pathways. Our previous studies suggested that diaminopimelic acid-type peptidoglycans (DAP-PG) from Gram-negative and some Gram-positive bacteria, more than Lys-type peptidoglycans (Lys-PG) from other Gram-positive bacteria, triggers both pathways through membrane-bound receptors orthologous to Drosophila Toll and PGRP-LC. In this study, we produced M. sexta proSpätzle-1 and proSpätzle-2 in Sf9 cells, identified their processing enzymes, and used prophenoloxidase activating protease-3 to activate the cytokine precursors. After Spätzle-1 and -2 were isolated from the reaction mixtures, we separately injected the purified cytokines into larval hemocoel to induce gene transcription in fat body through the Toll pathway solely. On the other hand, we treated a M. sexta cell line with E. coli DAP-PG to only induce the Imd pathway and target gene expression. RNA-Seq analysis of the fat body and cultured cells collected at 0, 6, and 24 h after treatment indicated that expression of diapausin-4, -10, -12, -13, cecropin-2, -4, -5, attacin-5, -11, and lebocin D is up-regulated predominantly via Toll signaling, whereas transcription of cecropin-6, gloverin, lysozyme-1, and gallerimycin-2 is mostly induced by DAP-PG via Imd signaling. Other antimicrobial peptides are expressed in response to both pathways. Transcripts of most Toll-specific genes (e.g., lebocin D) peaked at 6 h, contrasting the gradual increase and plateauing of drosomycin mRNA level at 24-48 h in Drosophila. We also used T (oll)-I (md) ratios to estimate relative contributions of the two pathways to transcriptional regulation of other components of the immune system. The differences in pathway specificity and time course of transcriptional regulation call for further investigations in M. sexta and other insects.
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Affiliation(s)
- Zelong Miao
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Chao Xiong
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Tisheng Shan
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA.
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Jin Q, Wang Y, Hu Y, He Y, Xiong C, Jiang H. Serine protease homolog pairs CLIPA4-A6, A4-A7Δ, and A4-A12 act as cofactors for proteolytic activation of prophenoloxidase-2 and -7 in Anopheles gambiae. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2024; 164:104048. [PMID: 38056530 PMCID: PMC10872527 DOI: 10.1016/j.ibmb.2023.104048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/20/2023] [Accepted: 11/29/2023] [Indexed: 12/08/2023]
Abstract
Phenoloxidase (PO) catalyzed melanization and other insect immune responses are mediated by serine proteases (SPs) and their noncatalytic homologs (SPHs). Many of these SP-like proteins have a regulatory clip domain and are called CLIPs. In most insects studied so far, PO precursors are activated by a PAP (i.e., PPO activating protease) and its cofactor of clip-domain SPHs. Although melanotic encapsulation is a well-known refractory mechanism of mosquitoes against malaria parasites, it is unclear if a cofactor is required for PPO activation. In Anopheles gambiae, CLIPA4 is 1:1 orthologous to Manduca sexta SPH2; CLIPs A5-7, A12-14, A26, A31, A32, E6, and E7 are 11:4 orthologous to M. sexta SPH1a, 1b, 4, and 101, SPH2 partners in the cofactors. Here we produced proCLIPs A4, A6, A7Δ, A12, and activated them with CLIPB9 or M. sexta PAP3. A. gambiae PPO2 and PPO7 were expressed in Escherichia coli for use as PAP substrates. CLIPB9 was mutated to CLIPB9Xa by including a Factor Xa cleavage site. CLIPA7Δ was a deletion mutant with a low complexity region removed. After PAP3 or CLIPB9Xa processing, CLIPA4 formed a high Mr complex with CLIPA6, A7Δ or A12, which assisted PPO2 and PPO7 activation. High levels of specific PO activity (55-85 U/μg for PO2 and 1131-1630 U/μg for PO7) were detected in vitro, indicating that cofactor-assisted PPO activation also occurs in this species. The cleavage sites and mechanisms for complex formation and cofactor function are like those reported in M. sexta and Drosophila melanogaster. In conclusion, these data suggest that the three (and perhaps more) SPHI-II pairs may form cofactors for CLIPB9-mediated activation of PPOs for melanotic encapsulation in A. gambiae.
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Affiliation(s)
- Qiao Jin
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Yingxia Hu
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Yan He
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Chao Xiong
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
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Jin Q, Wang Y, Yin H, Jiang H. Two clip-domain serine protease homologs, cSPH35 and cSPH242, act as a cofactor for prophenoloxidase-1 activation in Drosophila melanogaster. Front Immunol 2023; 14:1244792. [PMID: 37781370 PMCID: PMC10540698 DOI: 10.3389/fimmu.2023.1244792] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 08/16/2023] [Indexed: 10/03/2023] Open
Abstract
Insect phenoloxidases (POs) catalyze phenol oxygenation and o-diphenol oxidation to form reactive intermediates that kill invading pathogens and form melanin polymers. To reduce their toxicity to host cells, POs are produced as prophenoloxidases (PPOs) and activated by a serine protease cascade as required. In most insects studied so far, PPO activating proteases (PAPs) generate active POs in the presence of a high Mr cofactor, comprising two serine protease homologs (SPHs) each with a Gly residue replacing the catalytic Ser of an S1A serine protease (SP). These SPHs have a regulatory clip domain at the N-terminus, like most of the SP cascade members including PAPs. In Drosophila, PPO activation and PO-catalyzed melanization have been examined in genetic analyses but it is unclear if a cofactor is required for PPO activation. In this study, we produced the recombinant cSPH35 and cSPH242 precursors, activated them with Manduca sexta PAP3, and confirmed their predicted role as a cofactor for Drosophila PPO1 activation by MP2 (i.e., Sp7). The cleavage sites and mechanisms for complex formation and cofactor function are highly similar to those reported in M. sexta. In the presence of high Mr complexes of the cSPHs, PO at a high specific activity of 260 U/μg was generated in vitro. To complement the in vitro analysis, we measured hemolymph PO activity levels in wild-type flies, cSPH35, and cSPH242 RNAi lines. Compared with the wild-type flies, only 4.4% and 18% of the control PO level (26 U/μl) was detected in the cSPH35 and cSPH242 knockdowns, respectively. Consistently, percentages of adults with a melanin spot at the site of septic pricking were 82% in wild-type, 30% in cSPH35 RNAi, and 53% in cSPH242 RNAi lines; the survival rate of the control (45%) was significantly higher than those (30% and 15%) of the two RNAi lines. These data suggest that Drosophila cSPH35 and cSPH242 are components of a cofactor for MP2-mediated PPO1 activation, which are indispensable for early melanization in adults.
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Affiliation(s)
| | | | | | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, United States
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Shan T, Wang Y, Dittmer NT, Kanost MR, Jiang H. Serine Protease Networks Mediate Immune Responses in Extra-Embryonic Tissues of Eggs in the Tobacco Hornworm, Manduca sexta. J Innate Immun 2022; 15:365-379. [PMID: 36513034 PMCID: PMC10643904 DOI: 10.1159/000527974] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/01/2022] [Indexed: 12/15/2022] Open
Abstract
The melanization and Toll pathways, regulated by a network of serine proteases and noncatalytic serine protease homologs (SPHs), have been investigated mostly in adult and larval insects. However, how these innate immune reactions are regulated in insect eggs remains unclear. Here we present evidence from transcriptome and proteome analyses that extra-embryonic tissues (yolk and serosa) of early-stage Manduca sexta eggs are immune competent, with expression of immune effector genes including prophenoloxidase and antimicrobial peptides. We identified gene products of the melanization and Toll pathways in M. sexta eggs. Through in vitro reconstitution experiments, we demonstrated that constitutive and infection-induced serine protease cascade modules that stimulate immune responses exist in the extra-embryonic tissues of M. sexta eggs. The constitutive module (HP14b-SP144-GP6) may promote rapid early immune signaling by forming a cascade activating the cytokine Spätzle and regulating melanization by activating prophenoloxidase (proPO). The inducible module (HP14a-HP21-HP5) may trigger enhanced activation of Spätzle and proPO at a later phase of infection. Crosstalk between the two modules may occur in transition from the constitutive to the induced response in eggs inoculated with bacteria. Examination of data from two other well-studied insect species, Tribolium castaneum and Drosophila melanogaster, supports a role for a serosa-dependent constitutive protease cascade in protecting early embryos against invading pathogens.
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Affiliation(s)
- Tisheng Shan
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Neal T. Dittmer
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Michael R. Kanost
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, USA
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Zakhia R, Osta MA. CLIPA7 Exhibits Pleiotropic Roles in the Anopheles gambiae Immune Response. J Innate Immun 2022; 15:317-332. [PMID: 36423593 PMCID: PMC10643895 DOI: 10.1159/000526486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/09/2022] [Indexed: 10/30/2023] Open
Abstract
Clip domain serine proteases and clip domain serine protease homologs (cSPHs) are key components of serine protease cascades that drive the melanization response. Despite lacking catalytic activity, cSPHs play essential roles in regulating melanization, but the spectrum of functions they catalyze within and outside these cascades is not fully understood. Aside from their classical role as cofactors for PPO activation, we have previously revealed an unprecedented complexity in the function and molecular organization of these cSPHs in the immune response of the malaria vector Anopheles gambiae. Here, we add yet another dimension to the complex roles underpinning the contributions of cSPHs to mosquito immunity by showing that CLIPA7, a member of the expanded cSPH family, defines a novel branch within the cSPH network that is essential for the melanization of Escherichia coli but not Plasmodium ookinetes or Gram-positive bacteria. Despite its dispensability for the melanization of Gram-positive bacteria, we show that CLIPA7 is required for the clearance of systemic infections with Staphylococcus aureus. CLIPA7 is produced by hemocytes and associates with the surfaces of live E. coli and S. aureus cells in vivo as well as with those of melanized cells. Based on its RNAi phenotypes and its unique domain architecture among A. gambiae cSPHs including the presence of an RGD motif, we propose that CLIPA7 exhibits pleiotropic roles in mosquito immunity that extend beyond the regulation of melanization to microbial clearance.
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Affiliation(s)
| | - Mike A. Osta
- Department of Biology, American University of Beirut, Beirut, Lebanon
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Wang Y, Kanost MR, Jiang H. A mechanistic analysis of bacterial recognition and serine protease cascade initiation in larval hemolymph of Manduca sexta. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 148:103818. [PMID: 36007679 PMCID: PMC9890636 DOI: 10.1016/j.ibmb.2022.103818] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/20/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Serine protease cascades have evolved in vertebrates and invertebrates to mediate rapid defense responses. Previous biochemical studies showed that in hemolymph of a caterpillar, Manduca sexta, recognition of fungi by β-1,3-glucan recognition proteins (βGRP1 and βGRP2) or recognition of bacteria by peptidoglycan recognition protein-1 (PGRP1) and microbe binding protein (MBP) results in autoactivation of hemolymph protease-14 precursor (proHP14). HP14 then activates downstream members of a protease cascade leading to the melanization immune response. ProHP14 has a complex domain architecture, with five low-density lipoprotein receptor class A repeats at its amino terminus, followed by a Sushi domain, a Sushi domain variant called Wonton, and a carboxyl-terminal serine protease catalytic domain. Its zymogen form is activated by specific proteolytic cleavage at the amino-terminal end of the protease domain. While a molecular mechanism for recognition and triggering the response to β-1,3-glucan has been delineated, it is unclear how bacterial recognition stimulates proHP14 activation. To fill this knowledge gap, we expressed the two domains of M. sexta MBP and found that the amino-terminal domain binds to diaminopimelic acid-peptidoglycan (DAP-PG). ProHP14 bound to both the carboxyl-terminal domain (MBP-C) and amino-terminal domain (MBP-N) of MBP. In the mixture of DAP-PG, MBP, and larval plasma, inclusion of an HP14 fragment composed of LDLa repeats 2-5 (LDLa2-5) or MBP-C significantly reduced prophenoloxidase activation, likely by competing with the interactions of the full-length proteins, and suggesting that molecular interactions involving these regions of proHP14 and MBP take part in proHP14 activation in response to peptidoglycan. Using a series of N-terminally truncated versions of proHP14, we found that autoactivation required LDLa2-5. The optimal ratio of PGRP1, MBP, and proHP14 is close to 3:2:1. In summary, proHP14 autoactivation by DAP-type peptidoglycan requires binding of DAP-PG by PGRP1 and the MBP N-terminal domain and association of the LDLa2-5 region of proHP14 with the MBP C-terminal domain. These interactions may concentrate the proHP14 zymogen at the bacterial cell wall surface and promote autoactivation.
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Affiliation(s)
- Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, 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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Kariyawasam U, Gulati M, Wang Y, Bao H, Shan T, Li X, Cao X, Sumathipala N, Hu Y, Zhang X, Boons GJ, Jiang H. Preferential binding of DAP-PGs by major peptidoglycan recognition proteins found in cell-free hemolymph of Manduca sexta. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 148:103827. [PMID: 36007680 DOI: 10.1016/j.ibmb.2022.103827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 07/09/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
Peptidoglycan recognition proteins (PGRPs) detect invading bacteria to trigger or modulate immune responses in insects. While these roles are established in Drosophila, functional studies are not yet achieved at the PGRP family level in other insects. To attain this goal, we selected Manduca sexta PGRP12 and five of the nine secreted PGRPs for recombinant expression and biochemical characterization. We cloned PGRP2-5, 12 and 13 cDNAs, produced the proteins in full (PGRP2-5, 13) or in part (PGRP3s, 12e, 13N, 13C) in Sf9 cells, and tested their bindings of two muramyl pentapeptides by surface plasmon resonance, two soluble peptidoglycans by competitive ELISA, and four insoluble peptidoglycans and eight whole bacteria by a pull-down assay. Preferential binding of meso-diaminopimelic acid-peptidoglycans (DAP-PGs) was observed in all the proteins containing a peptidoglycan binding domain and, since PGRP6, 7 and 9 proteins were hardly detected in cell-free hemolymph, the reportoire of PGRPs (including PGRP1 published previously) in M. sexta hemolymph is likely adapted to mainly detect Gram-negative bacteria and certain Gram-positive bacteria with DAP-PGs located on their surface. After incubation with plasma from naïve larvae, PGRP2, 3f, 4, 5, 13f and 13N considerably stimulated prophenoloxidase activation in the absence of a bacterial elicitor. PGRP3s and 12e had much smaller effects. Inclusion of the full-length PGRPs and their regions in the plasma also led to proHP8 activation, supporting their connections to the Toll pathway, since HP8 is a Spӓtzle-1 processing enzyme in M. sexta. Together, these findings raised concerns on the common belief that the Toll-pathway is specific for Gram-positive bacteria in insects.
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Affiliation(s)
- Udeshika Kariyawasam
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA; Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Mansi Gulati
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Haibo Bao
- Institute of Plant Protection, Jiangshu Academy of Agricultural Sciences, Nanjing, 210014, PR China
| | - Tisheng Shan
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Xiuru Li
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, 30602, USA
| | - Xiaolong Cao
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA; Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Niranji Sumathipala
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Yingxia Hu
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA; Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Xiufeng Zhang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Geert-Jan Boons
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, 30602, USA
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA.
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Ji Y, Lu T, Zou Z, Wang Y. Aedes aegypti CLIPB9 activates prophenoloxidase-3 in the presence of CLIPA14 after fungal infection. Front Immunol 2022; 13:927322. [PMID: 35967454 PMCID: PMC9365933 DOI: 10.3389/fimmu.2022.927322] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 07/04/2022] [Indexed: 11/13/2022] Open
Abstract
Melanization is an integral part of the insect defense system and is often induced by pathogen invasion. Phenoloxidases (POs) are critical enzymes that catalyze melanin formation. PO3 is associated with the antifungal response of the mosquito, Aedes aegypti, but the molecular mechanism of the prophenoloxidase-3 (PPO3) activation is unclear. Here we report that PPO3 cleavage activation is mediated by a clip-domain serine protease, CLIPB9. We purified recombinant CLIPB9 and found that it cleaved PPO3 and increased PO activity in the hemolymph. We then identified CLIPA14 (a serine protease homolog) by co-immunoprecipitation using anti-CLIPB9 antibody. After being cleaved by CLIPB9, Ae. aegypti CLIPA14 acted as a cofactor for PPO3 activation. In addition, dsRNA co-silencing of CLIPB9 and CLIPA14 genes reduced melanization after infection with the entomopathogen, Beauveria bassiana, making the adult mosquitoes more sensitive to fungal infection. These results illustrate the roles of CLIPB9 and CLIPA14 in the PPO activation pathway and revealed the complexity of the upstream serine protease network controlling melanization.
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Affiliation(s)
- Yannan Ji
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Tengfei Lu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Zhen Zou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Yanhong Wang, ; Zhen Zou,
| | - Yanhong Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Yanhong Wang, ; Zhen Zou,
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Jin Q, Wang Y, Hartson SD, Jiang H. Cleavage activation and functional comparison of Manduca sexta serine protease homologs SPH1a, SPH1b, SPH4, and SPH101 in conjunction with SPH2. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 144:103762. [PMID: 35395380 PMCID: PMC9328667 DOI: 10.1016/j.ibmb.2022.103762] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/17/2022] [Accepted: 03/26/2022] [Indexed: 06/14/2023]
Abstract
Phenoloxidase (PO) is a crucial component of the insect immune response against microbial infection. In the tobacco hornworm Manduca sexta, PO is generated from its precursor proPO by prophenoloxidase activating proteases (PAPs) in the presence of two noncatalytic serine protease homologs (SPHs). cDNA cloning and genome analysis indicate that SPH1a (formerly known as SPH1), SPH1b, SPH4, SPH101, and SPH2 contain a clip domain, a linker, and a protease-like domain (PLD). The first 22 residues of the SPH1b, SPH4, and SPH101 PLDs are identical, and differ from SPH1a only at position 4, Thr154 substituted with Asn154 in SPH1a. While the sequence from Edman degradation was used to establish PAP cofactor as a high Mr complex of SPH1a and SPH2, this assignment needed further validation, especially because SPH1b mRNA levels are much higher than SPH1a's and better correlate with SPH2 transcription. Thus, here we determined expression profiles of these SPH genes in different tissues from various developmental stages using highly specific primers. High levels of SPH1b and SPH2 proteins, low SPH4, and no SPH1a or SPH101 were detected in hemolymph from larvae in the feeding, wandering and bar stages, pupae, and adults by targeted LC-MS/MS analysis, based on unique peptides from the trypsin-treated SPHs. We expressed the five proSPHs in baculovirus-infected Sf9 cells for use as standards to identify and quantify their counterparts in plasma samples. Moreover, we tested their cleavage by PAP3 and efficacy of the SPH1a, 1b, 4, and 101 as SPH2 partners in PAP3-mediated proPO activation. PAP3 processed proSPH1b and 101 more readily than proSPH1a and 4; PAP3 activated proPO more efficiently in the presence of SPH2 with SPH101 or SPH1b than with SPH1a or SPH4. These results generally agree with their order of appearance or sequence similarity: SPH101 > SPH1b (98%) > SPH1a (90%) > SPH4 (83%). In other words, likely due to positive selection, products of the newly duplicated genes (SPH1b and SPH101) are more favorable substrates of PAP3 and better SPH2 partners in forming a high Mr cofactor than SPH1a or SPH4 is. Electrophoresis on native gel and immunoblot analysis further indicated that SPH101 or 1b form high Mr complexes more readily than SPH1a or 4 does. In comparison, SPH2 showed a small mobility decrease and then increase on native gel after PAP3 cleavage at the first site. Since the natural cofactor in bar-stage hemolymph is complexes of SPH1 and 2 with an average Mr of 790 kDa, PAP3-activated SPH2 may associate with the higher Mr SPH1b scaffolds to form super-complexes. Their structures and formation in relation to cleavage of SPH1b at different sites await further exploration.
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Affiliation(s)
- Qiao Jin
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Steven D Hartson
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA.
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10
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Wang HC, Wang QH, Bhowmick B, Li YX, Han Q. Functional characterization of two clip domain serine proteases in innate immune responses of Aedes aegypti. Parasit Vectors 2021; 14:584. [PMID: 34819136 PMCID: PMC8611957 DOI: 10.1186/s13071-021-05091-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/08/2021] [Indexed: 11/12/2022] Open
Abstract
Background Clip domain serine proteases (CLIPs), a very diverse group of proteolytic enzymes, play a crucial role in the innate immunity of insects. Innate immune responses are the first line of defense in mosquitoes against the invasion of pathogenic microorganisms. The Toll pathway, immunodeficiency (IMD) pathway and melanization are the main processes of innate immunity in Aedes aegypti. CLIPS are classified into five subfamilies—CLIPA, CLIPB, CLIPC, CLIPD, and CLIPE—based on their sequence specificity and phylogenetic relationships. We report the functional characterization of the genes that code for two CLIPs in Ae. aegypti (Ae): Ae-CLIPB15 and Ae-CLIPB22. Methods Clustal Omega was used for multiple amino acid sequence alignment of Ae-CLIPB15 and Ae-CLIPB22 with different CLIP genes from other insect species. The spatiotemporal expression profiles of Ae-CLIPB15 and Ae-CLIPB22 were examined. We determined whether Ae-CLIPB15 and Ae-CLIPB22 respond to microbial challenge and tissue injury. RNA interference (RNAi) was used to explore the function of Ae-CLIPB15 and Ae-CLIPB22 in the defense of Ae. aegypti against bacterial and fungal infections. The expression levels of nuclear factor kappa B (NF-κB) transcription factors REL1 and REL2 in the Toll pathway and IMD pathway after bacterial infection were investigated. Finally, the change in phenoloxidase (PO) activity in Ae-CLIPB15 and Ae-CLIPB22 knockdown adults was investigated. Results We performed spatiotemporal gene expression profiling of Ae-CLIPB15 and Ae-CLIPB22 genes in Ae. aegypti using quantitative real-time polymerase chain reaction. These genes were expressed in different stages and tissues. The messenger RNA (mRNA) levels for both genes were also up-regulated by Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus aureus and fungal Beauveria bassiana infections, as well as in the tissue injury experiments. RNAi-mediated knockdown of Ae-CLIPB15 led to a significant decrease of PO activity in the hemolymph of Ae. aegypti, while other RNAi experiments revealed that both Ae-CLIPB15 and Ae-CLIPB22 were involved in immune defense against bacterial and fungal infections. The mRNA expression of NF-κB transcription factors REL1 and REL2 in the Toll pathway and IMD pathway differed between Ae-CLIPB15 and Ae-CLIPB22 knockdown mosquitoes infected with bacteria and wild type mosquitoes infected with bacteria. Conclusions Our findings suggest that Ae-CLIPB15 and Ae-CLIPB22 play a critical role in mosquito innate immunity, and that they are involved in immune responses to injury and infection. Their regulation of transcription factors and PO activity indicates that they also play a specific role in the regulation of innate immunity. Graphical Abstract ![]()
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Affiliation(s)
- Hao-Cheng Wang
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou, Hainan, 570228, People's Republic of China.,One Health Institute, Hainan University, Haikou, Hainan, 570228, People's Republic of China
| | - Qiu-Hui Wang
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou, Hainan, 570228, People's Republic of China.,One Health Institute, Hainan University, Haikou, Hainan, 570228, People's Republic of China
| | - Biswajit Bhowmick
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou, Hainan, 570228, People's Republic of China.,One Health Institute, Hainan University, Haikou, Hainan, 570228, People's Republic of China
| | - Yi-Xun Li
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou, Hainan, 570228, People's Republic of China.,One Health Institute, Hainan University, Haikou, Hainan, 570228, People's Republic of China
| | - Qian Han
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life Sciences, Hainan University, Haikou, Hainan, 570228, People's Republic of China. .,One Health Institute, Hainan University, Haikou, Hainan, 570228, People's Republic of China.
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11
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F. Q. Smith D, Casadevall A. Fungal immunity and pathogenesis in mammals versus the invertebrate model organism Galleria mellonella. Pathog Dis 2021; 79:ftab013. [PMID: 33544836 PMCID: PMC7981337 DOI: 10.1093/femspd/ftab013] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/03/2021] [Indexed: 02/07/2023] Open
Abstract
In recent decades, Galleria mellonella (Lepidoptera: Pyralidae) have emerged as a model system to explore experimental aspects of fungal pathogenesis. The benefits of the G. mellonella model include being faster, cheaper, higher throughput and easier compared with vertebrate models. Additionally, as invertebrates, their use is subject to fewer ethical and regulatory issues. However, for G. mellonella models to provide meaningful insight into fungal pathogenesis, the G. mellonella-fungal interactions must be comparable to mammalian-fungal interactions. Indeed, as discussed in the review, studies suggest that G. mellonella and mammalian immune systems share many similarities, and fungal virulence factors show conserved functions in both hosts. While the moth model has opened novel research areas, many comparisons are superficial and leave large gaps of knowledge that need to be addressed concerning specific mechanisms underlying G. mellonella-fungal interactions. Closing these gaps in understanding will strengthen G. mellonella as a model for fungal virulence in the upcoming years. In this review, we provide comprehensive comparisons between fungal pathogenesis in mammals and G. mellonella from immunological and virulence perspectives. When information on an antifungal immune component is unknown in G. mellonella, we include findings from other well-studied Lepidoptera. We hope that by outlining this information available in related species, we highlight areas of needed research and provide a framework for understanding G. mellonella immunity and fungal interactions.
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Affiliation(s)
- Daniel F. Q. Smith
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Arturo Casadevall
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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12
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Sousa GL, Bishnoi R, Baxter RHG, Povelones M. The CLIP-domain serine protease CLIPC9 regulates melanization downstream of SPCLIP1, CLIPA8, and CLIPA28 in the malaria vector Anopheles gambiae. PLoS Pathog 2020; 16:e1008985. [PMID: 33045027 PMCID: PMC7580898 DOI: 10.1371/journal.ppat.1008985] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 10/22/2020] [Accepted: 09/16/2020] [Indexed: 01/10/2023] Open
Abstract
The arthropod melanization immune response is activated by extracellular protease cascades predominantly comprised of CLIP-domain serine proteases (CLIP-SPs) and serine protease homologs (CLIP-SPHs). In the malaria vector, Anopheles gambiae, the CLIP-SPHs SPCLIP1, CLIPA8, and CLIPA28 form the core of a hierarchical cascade downstream of mosquito complement that is required for microbial melanization. However, our understanding of the regulatory relationship of the CLIP-SPH cascade with the catalytic CLIP-SPs driving melanization is incomplete. Here, we report on the development of a novel screen to identify melanization pathway components based on the quantitation of melanotic mosquito excreta, eliminating the need for microdissections or hemolymph enzymatic assays. Using this screen, we identified CLIPC9 and subsequent functional analyses established that this protease is essential for the melanization of both Escherichia coli and the rodent malaria parasite Plasmodium berghei. Mechanistically, septic infection with E. coli promotes CLIPC9 cleavage and both full-length and cleaved CLIPC9 localize to this bacterium in a CLIPA8-dependent manner. The steady state level of CLIPC9 in the hemolymph is regulated by thioester-containing protein 1 (TEP1), suggesting it functions downstream of mosquito complement. In support, CLIPC9 cleavage is inhibited following SPCLIP1, CLIPA8, and CLIPA28 knockdown positioning it downstream of the CLIP-SPH cascade. Moreover, like CLIPA8 and CLIPA28, CLIPC9 processing is negatively regulated by serine protease inhibitor 2 (SRPN2). This report demonstrates how our novel excretion-based approach can be utilized to dissect the complex protease networks regulating mosquito melanization. Collectively, our findings establish that CLIPC9 is required for microbial melanization in An. gambiae and shed light on how the CLIP-SPH cascade regulates this potent immune response.
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Affiliation(s)
- Gregory L. Sousa
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Ritika Bishnoi
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Richard H. G. Baxter
- Department of Medical Genetics and Molecular Biochemistry, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Michael Povelones
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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13
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Wang Y, Yang F, Cao X, Zou Z, Lu Z, Kanost MR, Jiang H. Hemolymph protease-5 links the melanization and Toll immune pathways in the tobacco hornworm, Manduca sexta. Proc Natl Acad Sci U S A 2020; 117:23581-23587. [PMID: 32900946 PMCID: PMC7519321 DOI: 10.1073/pnas.2004761117] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Proteolytic activation of phenoloxidase (PO) and the cytokine Spätzle during immune responses of insects is mediated by a network of hemolymph serine proteases (HPs) and noncatalytic serine protease homologs (SPHs) and inhibited by serpins. However, integration and conservation of the system and its control mechanisms are not fully understood. Here we present biochemical evidence that PO-catalyzed melanin formation, Spätzle-triggered Toll activation, and induced synthesis of antimicrobial peptides are stimulated via hemolymph (serine) protease 5 (HP5) in Manduca sexta Previous studies have demonstrated a protease cascade pathway in which HP14 activates proHP21; HP21 activates proPAP2 and proPAP3, which then activate proPO in the presence of a complex of SPH1 and SPH2. We found that both HP21 and PAP3 activate proHP5 by cleavage at ESDR176*IIGG. HP5 then cleaves proHP6 at a unique site of LDLH112*ILGG. HP6, an ortholog of Drosophila Persephone, activates both proHP8 and proPAP1. HP8 activates proSpätzle-1, whereas PAP1 cleaves and activates proPO. HP5 is inhibited by Manduca sexta serpin-4, serpin-1A, and serpin-1J to regulate its activity. In summary, we have elucidated the physiological roles of HP5, a CLIPB with unique cleavage specificity (cutting after His) that coordinates immune responses in the caterpillar.
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Affiliation(s)
- Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Fan Yang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Xiaolong Cao
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Zhen Zou
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Zhiqiang Lu
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078
| | - Michael R Kanost
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078;
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14
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Abstract
Insects possess powerful immune systems that have evolved to defend against wounding and environmental pathogens such as bacteria, fungi, protozoans, and parasitoids. This surprising sophistication is accomplished through the activation of multiple immune pathways comprised of a large array of components, many of which have been identified and studied in detail using both genetic manipulations and traditional biochemical techniques. Recent advances indicate that certain pathways activate arrays of proteins that interact to form large functional complexes. Here we discuss three examples from multiple insects that exemplify such processes, including pathogen recognition, melanization, and coagulation. The functionality of each depends on integrating recognition with the recruitment of immune effectors capable of healing wounds and destroying pathogens. In both melanization and coagulation, protein interactions also appear to be essential for enzymatic activities tied to the formation of melanin and for the recruitment of hemocytes. The importance of these immune complexes is highlighted by the evolution of mechanisms in pathogens to disrupt their formation, an example of which is provided. While technically difficult to study, and not always readily amenable to dissection through genetics, modern mass spectrometry has become an indispensable tool in the study of these higher-order protein interactions. The formation of immune complexes should be viewed as an essential and emerging frontier in the study of insect immunity.
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15
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El Moussawi L, Nakhleh J, Kamareddine L, Osta MA. The mosquito melanization response requires hierarchical activation of non-catalytic clip domain serine protease homologs. PLoS Pathog 2019; 15:e1008194. [PMID: 31765430 PMCID: PMC6901238 DOI: 10.1371/journal.ppat.1008194] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 12/09/2019] [Accepted: 11/05/2019] [Indexed: 12/20/2022] Open
Abstract
Serine protease cascades regulate important insect immune responses namely melanization and Toll pathway activation. An important component of these cascades are clip-domain serine protease homologs (cSPHs), which are non-catalytic, but essential for activating the enzyme prophenoloxidase (PPO) in the melanization response during septic infections. The activation of cSPHs requires their proteolytic cleavage, yet factors that control their activation and the complexity of their interactions within these cascades remain unclear. Here, we report the identification of CLIPA28 as a novel immune-related cSPH in the malaria vector Anopheles gambiae. Functional genetic analysis using RNA interference (RNAi) revealed that CLIPA28 is essential for the melanization of Plasmodium berghei parasites in refractory mosquitoes, and for mosquito resistance to fungal infections. We further show, using combined biochemical and genetic approaches, that CLIPA28 is member of a network of at least four cSPHs, whereby members are activated in a hierarchical manner following septic infections. Depletion of the complement-like protein TEP1 abolished the activation of this network after septic infections, whereas, depletion of the serine protease inhibitor 2 (SRPN2) triggered enhanced network activation, even in naïve mosquitoes, culminating in a dramatic reduction in cSPHs hemolymph levels, which paralleled that of PPO. Our data suggest that cSPHs are engaged in complex and multilayered interactions within serine protease cascades that regulate melanization, and identify TEP1 and SRPN2 as two master regulators of the cSPH network. Melanization is a spectacular immune response of insects that culminates in the deposition of melanin on microbial surfaces leading to their death. Despite more than half a century of investigation of this immune reaction in several insect models, important knowledge gaps, specifically concerning the regulation of this response, remain, especially that its output is tightly regulated by complex genetic and biochemical interactions between members of structurally diverse immune gene families. Here, we identify a new hemolymph protein that is involved in the melanization of malaria parasites and show that it forms, together with other proteins of the same gene family, a network, whereby members are activated in an orderly manner during mosquito septic infections. Furthemore, we show that this network is controlled by two structurally distinct immune proteins which act as master regulators of its activation. Dissecting the complexity of the regulatory mechanisms mediating insect melanization responses, may facilitate fine manipulation of mosquito immunity to reduce vectorial capacity.
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Affiliation(s)
- Layla El Moussawi
- Department of Biology, American University of Beirut, Beirut, Lebanon
| | - Johnny Nakhleh
- Department of Biology, American University of Beirut, Beirut, Lebanon
| | | | - Mike A. Osta
- Department of Biology, American University of Beirut, Beirut, Lebanon
- * E-mail:
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16
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Shakeel M, Xu X, De Mandal S, Jin F. Role of serine protease inhibitors in insect-host-pathogen interactions. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 102:e21556. [PMID: 31050038 DOI: 10.1002/arch.21556] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/03/2019] [Accepted: 04/15/2019] [Indexed: 06/09/2023]
Abstract
Serine protease inhibitors (serpins), evolutionary old, structurally conserved molecules, are a superfamily of proteins found in almost all living organisms. Serpins are relatively large, typically 350-500 amino acids in length, with three β-sheets and seven to nine α-helices folding into a conserved tertiary structure with a reactive center loop. Serpins perform various physiological functions in insects, including development, digestion, host-pathogen interactions, and innate immune response. In insects, the innate immune system is characterized as the first and major defense system against the invasion of microorganisms. Serine protease cascades play a critical role in the initiation of innate immune responses, such as melanization and the production of antimicrobial peptides, and are strictly and precisely regulated by serpins. Herein, we provide a microreview on the role of serpins in the insect-host-pathogen interactions, emphasizing their role in immune responses, particularly in diamondback moth (Plutella xylostella), highlighting the important discoveries and also the gaps that remain to be explored in future studies.
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Affiliation(s)
- Muhammad Shakeel
- Laboratory of Bio-Pesticide Creation and Application, Department of Entomology, College of Agriculture, South China Agricultural University, Guangzhou, China
| | - Xiaoxia Xu
- Laboratory of Bio-Pesticide Creation and Application, Department of Entomology, College of Agriculture, South China Agricultural University, Guangzhou, China
| | - Surajit De Mandal
- Laboratory of Bio-Pesticide Creation and Application, Department of Entomology, College of Agriculture, South China Agricultural University, Guangzhou, China
| | - Fengliang Jin
- Laboratory of Bio-Pesticide Creation and Application, Department of Entomology, College of Agriculture, South China Agricultural University, Guangzhou, China
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17
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Lin Z, Cheng Y, Wang RJ, Du J, Volovych O, Li JC, Hu Y, Lu ZY, Lu Z, Zou Z. A Metalloprotease Homolog Venom Protein From a Parasitoid Wasp Suppresses the Toll Pathway in Host Hemocytes. Front Immunol 2018; 9:2301. [PMID: 30405599 PMCID: PMC6206080 DOI: 10.3389/fimmu.2018.02301] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/17/2018] [Indexed: 12/18/2022] Open
Abstract
Parasitoid wasps depend on a variety of maternal virulence factors to ensure successful parasitism. Encapsulation response carried out by host hemocytes is one of the major host immune responses toward limiting endoparasitoid wasp offspring production. We found that VRF1, a metalloprotease homolog venom protein identified from the endoparasitoid wasp, Microplitis mediator, could modulate egg encapsulation in its host, the cotton bollworm, Helicoverpa armigera. Here, we show that the VRF1 proenzyme is cleaved after parasitism, and that the C-terminal fragment containing the catalytic domain enters host hemocytes 6 h post-parasitism. Furthermore, using yeast two-hybrid and pull-down assays, VRF1 is shown to interact with the H. armigera NF-κB factor, Dorsal. We also show that overexpressed of VRF1 in an H. armigera cell line cleaved Dorsal in vivo. Taken together, our results have revealed a novel mechanism by which a component of endoparasitoid wasp venom interferes with the Toll signaling pathway in the host hemocytes.
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Affiliation(s)
- Zhe Lin
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Yang Cheng
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Rui-Juan Wang
- Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Jie Du
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Olga Volovych
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Jian-Cheng Li
- Institute of Plant Protection of Hebei Academy of Agriculture and Forestry Sciences, Baoding, China
| | - Yang Hu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Zi-Yun Lu
- Institute of Plant Protection of Hebei Academy of Agriculture and Forestry Sciences, Baoding, China
| | - Zhiqiang Lu
- Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Zhen Zou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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18
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Lee KS, Kim BY, Choo YM, Jin BR. Dual role of the serine protease homolog BmSPH-1 in the development and immunity of the silkworm Bombyx mori. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 85:170-176. [PMID: 29684723 DOI: 10.1016/j.dci.2018.04.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 04/08/2018] [Accepted: 04/10/2018] [Indexed: 06/08/2023]
Abstract
Serine proteases and serine protease homologs are involved in the prophenoloxidase (proPO)-activating system leading to melanization. The Bombyx mori serine protease homolog BmSPH-1 regulates nodule melanization. Here, we show the dual role of BmSPH-1 in the development and immunity of B. mori. BmSPH-1 was expressed in hemocytes after molting and during the larval-pupal transformation in normal development. In contrast, following infection, BmSPH-1 was expressed in hemocytes and cleaved in the hemolymph, which resulted in the induction of PO activity. Moreover, BmSPH-1 was cleaved in the cuticle during the larval-pupal transformation and early pupal stages. In BmSPH-1 RNAi-treated silkworms, the reduced BmSPH-1 mRNA levels during the spinning stage or the prepupal stage resulted in the arrest of pupation or pupal cuticular melanization, respectively. The binding assays revealed that BmSPH-1 interacts with B. mori immulectin, proPO, and proPO-activating enzyme. Our findings demonstrate that BmSPH-1 paticipates larval-pupal transformation, pupal cuticular melanization and innate immunity of silkworms, illustrating the dual role of BmSPH-1 in development and immunity.
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Affiliation(s)
- Kwang Sik Lee
- Department of Applied Biology, College of Natural Resources and Life Science, Dong-A University, Busan, 604-714, Republic of Korea
| | - Bo Yeon Kim
- Department of Applied Biology, College of Natural Resources and Life Science, Dong-A University, Busan, 604-714, Republic of Korea
| | - Young Moo Choo
- Department of Applied Biology, College of Natural Resources and Life Science, Dong-A University, Busan, 604-714, Republic of Korea
| | - Byung Rae Jin
- Department of Applied Biology, College of Natural Resources and Life Science, Dong-A University, Busan, 604-714, Republic of Korea.
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19
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Yang F, Wang Y, Sumathipala N, Cao X, Kanost MR, Jiang H. Manduca sexta serpin-12 controls the prophenoloxidase activation system in larval hemolymph. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 99:27-36. [PMID: 29800677 PMCID: PMC5997545 DOI: 10.1016/j.ibmb.2018.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 04/28/2018] [Accepted: 05/14/2018] [Indexed: 06/01/2023]
Abstract
Insect prophenoloxidase activation is coordinated by a serine protease network, which is regulated by serine protease inhibitors of the serpin superfamily. The enzyme system also leads to proteolytic processing of a Spätzle precursor. Binding of Spätzle to a Toll receptor turns on a signaling pathway to induce the synthesis of defense proteins. Previous studies of the tobacco hornworm Manduca sexta have revealed key members of the protease cascade, which generates phenoloxidase for melanogenesis and Spätzle to induce immunity-related genes. Here we provide evidence that M. sexta serpin-12 regulates hemolymph protease-14 (HP14), an initiating protease of the cascade. This inhibitor, unlike the other serpins characterized in M. sexta, has an amino-terminal extension rich in hydrophilic residues and an unusual P1 residue (Leu429) right before the scissile bond cleaved by a target protease. Serpins with similarities to serpin-12, including Drosophila Necrotic, were identified in a wide range of insects including flies, moths, wasps, beetles, and two hemimetabolous species. The serpin-12 mRNA is present at low, constitutive levels in larval fat body and hemocytes and becomes more abundant after an immune challenge. We produced the serpin-12 core domain (serpin-12ΔN) in insect cells and in Escherichia coli and demonstrated its inhibition of human cathepsin G, bovine α-chymotrypsin, and porcine pancreatic elastase. MALDI-TOF analysis of the reaction mixtures confirmed the predicted P1 residue of Leu429. Supplementation of larval plasma samples with the serpin-12ΔN decreased prophenoloxidase activation elicited by microbial cells and reduced the proteolytic activation of the protease precursors of HP6, HP8, PAPs, and other serine protease-related proteins. After incubation of plasma stimulated with peptidoglycan, a 72 kDa protein appeared, which was recognized by polyclonal antibodies against both serpin-12 and HP14, suggesting that a covalent serpin-protease complex formed when serpin-12 inhibited HP14. Together, these data suggest that M. sexta serpin-12 inhibits HP14 to regulate melanization and antimicrobial peptide induction.
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Affiliation(s)
- Fan Yang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Niranji Sumathipala
- 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
| | - 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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20
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Zhang H, Tang B, Lin Y, Chen Z, Zhang X, Ji T, Zhang X, Hou Y. Identification of three prophenoloxidase-activating factors (PPAFs) from an invasive beetle Octodonta nipae Maulik (Coleoptera: Chrysomelidae) and their roles in the prophenoloxidase activation. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2017; 96:e21425. [PMID: 28990217 DOI: 10.1002/arch.21425] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A typical characteristic of the insect innate immune system is the activation of the serine protease cascade in the hemolymph. As being the terminal component of the extracellular serine protease cascade in the prophenoloxidase (proPO) activating system, proPO-activating factors (PPAFs) activated by the upstream cascade may generate active phenoloxidase, which then induces downstream melanization. In the present study, we reported three PPAFs from the nipa palm hispid beetle Octodonta nipae (Maulik) (designated as OnPPAF1, OnPPAF2, OnPPAF3). All three OnPPAFs contained a single clip domain at the amino-terminus followed by a trypsin-like serine protease domain at the carboxyl-terminus, except the Ser in the active sites of OnPPAF2 and OnPPAF3 was substituted with Gly. Transcript expression analysis revealed that all OnPPAFs were highly expressed in hemolymph, whereas OnPPAF2 showed an extremely low mRNA abundance compared with that of OnPPAF1 and OnPPAF3, and that the abundance of all three OnPPAFs was dramatically increased upon bacterial challenge. Knockdown of OnPPAF1 or OnPPAF3 resulted in a reduction of hemolymph phenoloxidase activity and an inhibition of hemolymph melanization, whereas the knockdown of OnPPAF2 did not affect the proPO cascade. Our work thus implies that the three OnPPAFs may have different functions and regulation during immune responses in O. nipae.
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Affiliation(s)
- HuaJian Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Provincial Key Laboratory of Insect Ecology, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - BaoZhen Tang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Provincial Key Laboratory of Insect Ecology, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - YaPing Lin
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Provincial Key Laboratory of Insect Ecology, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - ZhiMing Chen
- Fuzhou Entry-Exit Inspection & Quarantine Bureau of P.R.C., Fuzhou, China
| | - XiaFang Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Provincial Key Laboratory of Insect Ecology, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - TianLiang Ji
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Provincial Key Laboratory of Insect Ecology, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - XiaoMei Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Provincial Key Laboratory of Insect Ecology, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - YouMing Hou
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Provincial Key Laboratory of Insect Ecology, Department of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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He Y, Wang Y, Yang F, Jiang H. Manduca sexta hemolymph protease-1, activated by an unconventional non-proteolytic mechanism, mediates immune responses. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 84:23-31. [PMID: 28366787 PMCID: PMC5461656 DOI: 10.1016/j.ibmb.2017.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 03/06/2017] [Accepted: 03/28/2017] [Indexed: 05/27/2023]
Abstract
Tissue damage or pathogen invasion triggers the auto-proteolysis of an initiating serine protease (SP), rapidly leading to sequential cleavage activation of other cascade members to set off innate immune responses in insects. Recently, we presented evidence that Manduca sexta hemolymph protease-1 zymogen (proHP1) is a member of the SP system in this species, and may activate proHP6. HP6 stimulates melanization and induces antimicrobial peptide synthesis. Here we report that proHP1 adopts an active conformation (*) to carry out its function, without a requirement for proteolytic activation. Affinity chromatography using HP1 antibodies isolated from induced hemolymph the 48 kDa proHP1 and also a 90 kDa band (detected by SDS-PAGE under reducing conditions) containing proHP1 and several serpins, as revealed by mass spectrometric analysis. Identification of tryptic peptides from these 90 kDa complexes included peptides from the amino-terminal regulatory part of proHP1, indicating that proHP1* was not cleaved, and that it had formed a complex with the serpins. As suicide inhibitors, serpins form SDS-stable, acyl-complexes when they are attacked by active proteases, indicating that proHP1* was catalytically active. Detection of M. sexta serpin-1, 4, 9, 13 and smaller amounts of serpin-3, 5, 6 in the complexes suggests that it is regulated by multiple serpins in hemolymph. We produced site-directed mutants of proHP1b for cleavage by bovine blood coagulation factor Xa at the designed proteolytic activation site, to generate a form of proHP1b that could be activated by Factor Xa. However, proHP1b cut by Factor Xa failed to activate proHP6 and, via HP6, proHP8 or proPAP1. This negative result is consistent with the suggestion that proHP1* is a physiological mediator of immune responses. Further research is needed to investigate the conformational change that results in conversion of proHP1 to active proHP1*.
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Affiliation(s)
- Yan He
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Fan Yang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
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Wang Y, Jiang H. Prophenoloxidase activation and antimicrobial peptide expression induced by the recombinant microbe binding protein of Manduca sexta. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 83:35-43. [PMID: 27989837 PMCID: PMC5461653 DOI: 10.1016/j.ibmb.2016.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/04/2016] [Accepted: 10/24/2016] [Indexed: 05/09/2023]
Abstract
Manduca sexta microbe binding protein (MBP) is a member of the β-1,3-glucanase-related protein superfamily that includes Gram-negative bacteria-binding proteins (GNBPs), β-1,3-glucan recognition proteins (βGRPs), and β-1,3-glucanases. Our previous and current studies showed that the purified MBP from baculovirus-infected insect cells had stimulated prophenoloxidase (proPO) activation in the hemolymph of naïve and immune challenged larvae and that supplementation of the exogenous MBP and peptidoglycans (PGs) had caused synergistic increases in PO activity. To explore the underlying mechanism, we separated by SDS-PAGE naïve and induced larval plasma treated with buffer or MBP and detected on immunoblots changes in intensity and/or mobility of hemolymph (serine) proteases [HP14, HP21, HP6, HP8, proPO-activating proteases (PAPs) 1-3] and their homologs (SPH1, SPH2). In a nickel pull-down assay, we observed association of MBP with proHP14 (slightly), βGRP2, PG recognition protein-1 (PGRP1, indirectly), SPH1, SPH2, and proPO2. Further experiments indicated that diaminopimelic acid (DAP) or Lys PG, MBP, PGRP1, and proHP14 together trigger the proPO activation system in a Ca2+-dependent manner. Injection of the recombinant MBP into the 5th instar naïve larvae significantly induced the expression of several antimicrobial peptide genes, revealing a possible link between HP14 and immune signal transduction. Together, these results suggest that the recognition of Gram-negative or -positive bacteria via their PGs induces the melanization and Toll pathways in M. sexta.
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Affiliation(s)
- Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, United States
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, United States.
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Yang F, Wang Y, He Y, Jiang H. In search of a function of Manduca sexta hemolymph protease-1 in the innate immune system. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 76:1-10. [PMID: 27343384 PMCID: PMC5011066 DOI: 10.1016/j.ibmb.2016.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 06/15/2016] [Accepted: 06/21/2016] [Indexed: 05/24/2023]
Abstract
Extracellular serine protease cascades mediate immune signaling and responses in insects. In the tobacco hornworm Manduca sexta, nearly 30 serine proteases (SPs) and their homologs (SPHs) are cloned from hemocytes and fat body. Some of them participate in prophenoloxidase (proPO) activation and proSpätzle processing. Here we report the cDNA cloning of hemolymph protease-1b (HP1b), which is 90% identical and 95% similar to HP1a (formerly HP1). The HP1a and HP1b mRNA levels in hemocytes was down- and up-regulated after an immune challenge, respectively. Quantitative real-time polymerase chain reactions revealed their tissue-specific and development-dependent expression, mostly in hemocytes of the feeding larvae. We isolated HP1 precursor (proHP1) from larval hemolymph and observed micro-heterogeneity caused by N-linked glycosylation. Supplementation of the purified proHP1 to plasma samples from naïve larvae or induced ones injected with bacteria caused a small PO activity increase, much lower than those elicited by recombinant proHP1a/b, but no proteolytic cleavage was detected in the zymogens. Incubation of proHP1a/b or their catalytic domains with a cationic detergent, cetylpyridinium chloride, induced an amidase activity that hydrolyzed LDLH-p-nitroanilide. Since LDLH corresponds to the P4-P1 region before the proteolytic activation site of proHP6, we propose that the active but uncleaved proHP1 may cut proHP6 to generate HP6 that in turn activates proPAP1 and proHP8. The catalytic domain of HP1a/b, which by itself does not activate purified proHP6 or hydrolyze LDLH-p-nitroanilide, somehow generated active HP6, HP8, PAP1 and PO in plasma. Together, these results indicate that proHP1 participates in the proPO activation system, although detailed mechanism needs further exploration.
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Affiliation(s)
- Fan Yang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, United States
| | - Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, United States
| | - Yan He
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, United States
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, United States.
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Shu M, Mang D, Fu GS, Tanaka S, Endo H, Kikuta S, Sato R. Mechanisms of nodule-specific melanization in the hemocoel of the silkworm, Bombyx mori. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 70:10-23. [PMID: 26707571 DOI: 10.1016/j.ibmb.2015.12.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/26/2015] [Accepted: 12/15/2015] [Indexed: 06/05/2023]
Abstract
In the insect immune system, nodules are known to be a product of the cellular response against microorganisms and may be a preferential target for melanization. However, the mechanism of nodule-preferential melanization remains to be explored. In this study, we identified several mechanisms of nodule-preferential melanization by analyzing congregation and the activation of several factors involved in the prophenoloxidase (proPO)-activating system in the silkworm, Bombyx mori. Microorganism-binding assays revealed that B. mori larval plasma have an effective invading microorganism-surveillance network consisting of at least six pattern-recognition receptors (PRRs). We also found that a hemolymph serine proteinase, BmHP14, can bind to Saccharomyces cerevisiae. Pull-down assays showed that PRR C-type lectins form protein complexes with serine proteinase homologs, BmSPH1 and BmSPH2, which leads to the activated forms of BmSPH1 and BmSPH2 being gathered on microorganisms and trapped in nodules. Immunostaining analysis revealed that most factors in the proPO-activating system and some factors in the triggering system for antimicrobial peptide production exist in the granules of hemocytes which can gather in nodules. Western blot analysis showed that factors in the proPO-activating system are congregated in formed nodules by their concentration in plasma and aggregating hemocytes.
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Affiliation(s)
- Min Shu
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Dingze Mang
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Gege Sun Fu
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Shiho Tanaka
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Haruka Endo
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Shingo Kikuta
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Application and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan.
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Chu Y, Liu Y, Shen D, Hong F, Wang G, An C. Serine proteases SP1 and SP13 mediate the melanization response of Asian corn borer, Ostrinia furnacalis, against entomopathogenic fungus Beauveria bassiana. J Invertebr Pathol 2015; 128:64-72. [PMID: 25900291 DOI: 10.1016/j.jip.2015.02.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 02/12/2015] [Accepted: 02/26/2015] [Indexed: 01/01/2023]
Abstract
Exposure to entomopathogenic fungi is one approach for insect pest control. Little is known about the immune interactions between fungus and its insect host. Melanization is a prominent immune response in insects in defending against pathogens such as bacteria and fungi. Clip domain serine proteases in insect plasma have been implicated in the activation of prophenoloxidase, a key enzyme in the melanization. The relationship between host melanization and the infection by a fungus needs to be established. We report here that the injection of entomopathogenic fungus Beauveria bassiana induced both melanin synthesis and phenoloxidase activity in its host insect, the Asian corn borer, Ostrinia furnacalis (Guenée). qRT-PCR analysis showed several distinct patterns of expression of 13 clip-domain serine proteases in response to the challenge of fungi, with seven increased, two decreased, and four unchanged. Of special interest among these clip-domain serine protease genes are SP1 and SP13, the orthologs of Manduca sexta HP6 and PAP1 which are involved in the prophenoloxidase activation pathway. Recombinant O. furnacalis SP1 was found to activate proSP13 and induce the phenoloxidase activity in corn borer plasma. Additionally, SP13 was determined to directly cleave prophenoloxidase and therefore act as the prophenoloxidase activating protease. Our work thus reveals a biochemical mechanism in the melanization in corn borer associated with the challenge by B. bassiana injection. These insights could provide valuable information for better understanding the immune responses of Asian corn borer against B. bassiana.
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Affiliation(s)
- Yuan Chu
- Department of Entomology, College of Agriculture and Biotechnology, China Agricultural University, Beijing, China
| | - Yang Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Dongxu Shen
- Department of Entomology, College of Agriculture and Biotechnology, China Agricultural University, Beijing, China
| | - Fang Hong
- Department of Entomology, College of Agriculture and Biotechnology, China Agricultural University, Beijing, China
| | - Guirong Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Chunju An
- Department of Entomology, College of Agriculture and Biotechnology, China Agricultural University, Beijing, China.
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26
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Clark KD. Altered tyrosine metabolism and melanization complex formation underlie the developmental regulation of melanization in Manduca sexta. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 58:66-75. [PMID: 25596090 DOI: 10.1016/j.ibmb.2015.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 01/06/2015] [Accepted: 01/06/2015] [Indexed: 06/04/2023]
Abstract
The study of hemolymph melanization in Lepidoptera has contributed greatly to our understanding of its role in insect immunity. Manduca sexta in particular has been an excellent model for identifying the myriad components of the phenoloxidase (PO) cascade and their activation through exposure to pathogen-associated molecular patterns (PAMPs). However, in a process that is not well characterized or understood, some insect species rapidly melanize upon wounding in the absence of added PAMPs. We sought to better understand this process by measuring wound-induced melanization in four insect species. Of these, only plasma from late 5th instar M. sexta was unable to melanize, even though each contained millimolar levels of the putative melanization substrate tyrosine (Tyr). Analysis of Tyr metabolism using substrate-free plasmas (SFPs) from late 5th instar larvae of each species showed that only M. sexta SFP failed to melanize with added Tyr. In contrast, early instar M. sexta larvae exhibited wound-induced melanization and Tyr metabolism, and SFPs prepared from these larvae melanized in the presence of Tyr. Early instar melanization in M. sexta was associated with the formation of a high mass protein complex that could be observed enzymatically in native gels or by PO-specific immunoblotting. Topical treatment of M. sexta larvae with the juvenile hormone (JH) analog methoprene delayed pupation and increased melanizing ability late in the instar, thus linking development with immunity. Our results demonstrate that melanization rates are highly variable in Lepidoptera, and that developmental stage can be an important factor for melanization within a species. More specifically, we show that the physiological substrate for melanization in M. sexta is Tyr, and that melanization is associated with the formation of a PO-containing protein complex.
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Affiliation(s)
- Kevin D Clark
- Department of Entomology, University of Georgia, Athens, GA 30602, USA.
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27
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Wang Y, Lu Z, Jiang H. Manduca sexta proprophenoloxidase activating proteinase-3 (PAP3) stimulates melanization by activating proPAP3, proSPHs, and proPOs. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2014; 50:82-91. [PMID: 24768974 PMCID: PMC4064829 DOI: 10.1016/j.ibmb.2014.04.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 04/09/2014] [Accepted: 04/10/2014] [Indexed: 05/22/2023]
Abstract
Melanization participates in various insect physiological processes including antimicrobial immune responses. Phenoloxidase (PO), a critical component of the enzyme system catalyzing melanin formation, is produced as an inactive precursor prophenoloxidase (proPO) and becomes active via specific proteolytic cleavage by proPO activating proteinase (PAP). In Manduca sexta, three PAPs can activate proPOs in the presence of two serine proteinase homologs (SPH1 and SPH2). While the hemolymph proteinases (HPs) that generate the active PAPs are known, it is unclear how the proSPHs (especially proSPH1) are activated. In this study, we isolated from plasma of bar-stage M. sexta larvae an Ile-Glu-Ala-Arg-p-nitroanilide hydrolyzing enzyme that cleaved the proSPHs. This proteinase, PAP3, generated active SPH1 and SPH2, which function as cofactors for PAP3 in proPO activation. Cleavage of the purified recombinant proSPHs by PAP3 yielded 38 kDa bands similar in mobility to the SPHs formed in vivo. Surprisingly, PAP3 also can activate proPAP3 to stimulate melanization in a direct positive feedback loop. The enhanced proPO activation concurred with the cleavage activation of proHP6, proHP8, proPAP1, proPAP3, proSPH1, proSPH2, proPOs, but not proHP14 or proHP21. These results indicate that PAP3, like PAP1, is a key factor of the self-reinforcing mechanism in the proPO activation system, which is linked to other immune responses in M. sexta.
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Affiliation(s)
- Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Zhiqiang Lu
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
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28
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Tokura A, Fu GS, Sakamoto M, Endo H, Tanaka S, Kikuta S, Tabunoki H, Sato R. Factors functioning in nodule melanization of insects and their mechanisms of accumulation in nodules. JOURNAL OF INSECT PHYSIOLOGY 2014; 60:40-49. [PMID: 24262307 DOI: 10.1016/j.jinsphys.2013.11.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 10/16/2013] [Accepted: 11/07/2013] [Indexed: 06/02/2023]
Abstract
Nodules consisting of hemocytes and trapped microorganisms are important targets for melanization, which is best known in the insect immune system. We investigated factors functioning in nodule melanization and the mechanism by which these factors congregate in the nodule. BmHP21, BmSPH1 and BmSPH2, Bombyx mori orthologs of Manduca sexta serine protease HP21, serine protease homologs (SPH1 and SPH2), and a prophenoloxidase, BmPO1 were observed as inactive forms in the plasma, but as putatively active forms in the nodule. Production of prophenoloxidase-activating proteinases, BmPAP1 and BmPAP3/PPAE and BmPO1 were confirmed in hemocytes. BmSPH1 and BmSPH2 were observed on trapped bacterial cells in the nodule and were isolated from the surface of bacterial cells incubated with plasma. BmSPH1 and BmSPH2 were found in plasma in complex with a pattern recognition receptor, BmLBP. These data suggest that melanization-regulating factors congregate in nodules through a combination of microorganism-dependent and hemocyte-dependent routes.
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Affiliation(s)
- Ai Tokura
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Gege Sun Fu
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Maki Sakamoto
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Haruka Endo
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Shiho Tanaka
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Shingo Kikuta
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Hiroko Tabunoki
- Department of Biological Production, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwai-cho 3-5-8, Fuchu, Tokyo 183-8509, Japan
| | - Ryoichi Sato
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan.
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29
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Toubarro D, Avila MM, Montiel R, Simões N. A pathogenic nematode targets recognition proteins to avoid insect defenses. PLoS One 2013; 8:e75691. [PMID: 24098715 PMCID: PMC3787073 DOI: 10.1371/journal.pone.0075691] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 08/20/2013] [Indexed: 01/18/2023] Open
Abstract
Steinernemacarpocapsae is a nematode pathogenic in a wide variety of insect species. The great pathogenicity of this nematode has been ascribed to its ability to overcome the host immune response; however, little is known about the mechanisms involved in this process. The analysis of an expressed sequence tags (EST) library in the nematode during the infective phase was performed and a highly abundant contig homologous to serine protease inhibitors was identified. In this work, we show that this contig is part of a 641-bp cDNA that encodes a BPTI-Kunitz family inhibitor (Sc-KU-4), which is up-regulated in the parasite during invasion and installation. Recombinant Sc-KU-4 protein was produced in Escherichia coli and shown to inhibit chymotrypsin and elastase activities in a dose-dependent manner by a competitive mechanism with Ki values of 1.8 nM and 2.6 nM, respectively. Sc-KU-4 also inhibited trypsin and thrombin activities to a lesser extent. Studies of the mode of action of Sc-KU-4 and its effects on insect defenses suggest that although Sc-KU-4 did not inhibit the activation of hemocytes or the formation of clotting fibers, it did inhibit hemocyte aggregation and the entrapment of foreign particles by fibers. Moreover, Sc-KU-4 avoided encapsulation and the deposition of clotting materials, which usually occurs in response to foreign particles. We show by protein-protein interaction that Sc-KU-4 targets recognition proteins of insect immune system such as masquerade-like and serine protease-like homologs. The interaction of Sc-KU-4 with these proteins explains the ability of the nematode to overcome host reactions and its large pathogenic spectrum, once these immune proteins are well conserved in insects. The discovery of this inhibitor targeting insect recognition proteins opens new avenues for the development of S. carpocapsae as a biological control agent and provides a new tool to study host-pathogen interactions.
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Affiliation(s)
- Duarte Toubarro
- IBB/CBA and CIRN/Departamento de Biologia, Universidade dos Açores, Ponta Delgada, Portugal
| | - Mónica Martinez Avila
- IBB/CBA and CIRN/Departamento de Biologia, Universidade dos Açores, Ponta Delgada, Portugal
| | - Rafael Montiel
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Irapuato, Guanajuato, Mexico
| | - Nelson Simões
- IBB/CBA and CIRN/Departamento de Biologia, Universidade dos Açores, Ponta Delgada, Portugal
- * E-mail:
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Zhao P, Wang Y, Jiang H. Biochemical properties, expression profiles, and tissue localization of orthologous acetylcholinesterase-2 in the mosquito, Anopheles gambiae. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:260-271. [PMID: 23267863 PMCID: PMC3578101 DOI: 10.1016/j.ibmb.2012.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 12/06/2012] [Accepted: 12/14/2012] [Indexed: 06/01/2023]
Abstract
Acetylcholinesterases (AChEs) catalyze the hydrolysis of acetylcholine, a neurotransmitter for cholinergic neurotransmission in animals. Most insects studied so far possess two AChE genes: ace-1 paralogous and ace-2 orthologous to Drosophila melanogaster ace. We characterized the catalytic domain of Anopheles gambiae AChE1 in a previous study (Jiang et al., 2009) and report here biochemical properties of A. gambiae AChE2 expressed in Sf9 cells. An unknown protease in the expression system cleaved the recombinant AChE2 next to Arg(110), yielding two non-covalently associated polypeptides. A mixture of the intact and cleaved AChE2 had a specific activity of 72.3 U/mg, much lower than that of A. gambiae AChE1 (523 U/mg). The order of V(max)/K(M) values for the model substrates was acetylthiocholine > propionylthiocholine ≈ acetyl-(β-methyl)thiocholine > butyrylthiocholine. The IC(50)'s for eserine, carbaryl, BW284C51, paraoxon and malaoxon were 1.32, 13.6, 26.8, 192 and 294 nM, respectively. A. gambiae AChE2 bound eserine and carbaryl stronger than paraoxon and malaoxon, whereas eserine and malaoxon modified the active site Ser(232) faster than carbaryl or paraoxon did. Consequently, the k(i)'s were 1.173, 0.245, 0.029 and 0.018 μM(-1)min(-1) for eserine, carbaryl, paraoxon and malaoxon, respectively. Quantitative polymerase chain reactions showed a similar pattern of ace-1 and ace-2 expression. Their mRNAs were abundant in early embryos, greatly decreased in late embryos, larvae, pupae, and pharate adult, and became abundant again in adults. Both transcripts were higher in head and abdomen than thorax of adults and higher in male than female mosquitoes. Transcript levels of ace-1 were 1.9- to 361.8-fold higher than those of ace-2, depending on developmental stages and body parts. Cross-reacting polyclonal antibodies detected AChEs in adult brains, thoracic ganglia, and genital/rectal area. Activity assays, immunoblotting, and tandem mass spectrometric analysis indicated that A. gambiae AChE1 is responsible for most of acetylthiocholine hydrolysis in the head extracts. Taken together, these data indicate that A. gambiae AChE2 may play a less significant role than AChE1 does in the mosquito nervous system.
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Affiliation(s)
- Picheng Zhao
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Wang Y, Sumathipala N, Rayaprolu S, Jiang H. Recognition of microbial molecular patterns and stimulation of prophenoloxidase activation by a β-1,3-glucanase-related protein in Manduca sexta larval plasma. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 41:322-31. [PMID: 21296155 PMCID: PMC3066292 DOI: 10.1016/j.ibmb.2011.01.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 01/03/2011] [Accepted: 01/27/2011] [Indexed: 05/03/2023]
Abstract
Detection of pathogenic invaders is the essential first step of a successful defense response in multicellular organisms. In this study, we have identified a new member of the β-1,3-glucanase-related protein superfamily from the tobacco hornworm Manduca sexta. This protein, designated microbe binding protein (MBP), is 61% identical in sequence to Bombyx mori Gram-negative bacteria binding protein, but only 34-36% identical to M. sexta β-1,3-glucan recognition protein-1 and 2. Its mRNA levels were strongly up-regulated in hemocytes and fat body of immune challenged larvae, along with an increase in concentration of the plasma protein. We expressed M. sexta MBP in a baculovirus-insect cell system. The purified protein associated with intact bacteria and fungi. It specifically bound to lipoteichoic acid, lipopolysaccharide, diaminopimelic acid-type peptidoglycans (DAP-PGs) from Escherichia coli and Bacillus subtilis, but less so to laminarin or Lys-type PG from Staphylococcus aureus. The complex binding pattern was influenced by other plasma factors and additional microbial surface molecules. After different amounts of MBP had been incubated with larval plasma on ice, a concentration-dependent increase in phenoloxidase (PO) activity occurred in the absence of any microbial elicitor. The activity increase was also observed in the mixture of plasma and a bacterial or fungal cell wall component. The prophenoloxidase (proPO) activation became more prominent when DAP-PGs, Micrococcus luteus Lys-PG, or lipoteichoic acid was included in the mixture of MBP and plasma. Statistic analysis suggested that a synergistic enhancement of proPO activation was caused by an interaction between MBP and these elicitors, but not S. aureus Lys-PG, lipopolysaccharide, curdlan, or laminarin. These data indicate that M. sexta MBP is a component of the surveillance mechanism and, by working together with other pattern recognition molecules and serine proteinases, triggers the proPO activation system.
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Affiliation(s)
- Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Sakamoto M, Ohta M, Suzuki A, Takase H, Yoshizawa Y, Kitami M, Sato R. Localization of the serine protease homolog BmSPH-1 in nodules of E. coli-injected Bombyx mori larvae and functional analysis of its role in nodule melanization. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2011; 35:611-619. [PMID: 21237196 DOI: 10.1016/j.dci.2011.01.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 01/09/2011] [Accepted: 01/09/2011] [Indexed: 05/30/2023]
Abstract
The molecular mechanisms underlying nodule formation and melanization, an important pathogen defense mechanism in insects, are poorly understood. In this study, we investigated the role of BmSPH-1, a catalytically inactive Bombyx mori serine protease homolog, in nodule melanization induced by injection of Escherichia coli cells into the B. mori larval hemocoel. Addition of the melanization substrate L-3,4-dihydroxyphenylalanine (DOPA) to newly formed nodules prompted nodule melanization, confirming that nodules contain activated prophenoloxidase needed for melanization. Immunoprecipitation and immunoblot studies demonstrated that BmSPH-1 interacts with BmLBP, a C-type lectin that binds Gram-negative bacteria, and that BmSPH-1 is present in a truncated, putatively activated form at the E. coli cell surface in nodules. Pretreatment of larvae with anti-BmSPH-1 serum inhibited nodule melanization in E. coli-injected larvae. These results suggest that BmSPH-1 regulates nodule melanization and is recruited into nodules from the hemolymph by BmLBP.
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Affiliation(s)
- Maki Sakamoto
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei 2-24-16, Tokyo 184-8588, Japan
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Liu HP, Chen RY, Zhang M, Wang KJ. Isolation, gene cloning and expression profile of a pathogen recognition protein: a serine proteinase homolog (Sp-SPH) involved in the antibacterial response in the crab Scylla paramamosain. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2010; 34:741-748. [PMID: 20153768 DOI: 10.1016/j.dci.2010.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2010] [Revised: 02/05/2010] [Accepted: 02/06/2010] [Indexed: 05/28/2023]
Abstract
To identify the frontline defense molecules against microbial infection in the crab Scylla paramamosain, a live crab pathogenic microbe, Vibrio parahaemolyticus, was recruited as an affinity matrix to isolate innate immune factors from crab hemocytes lysate. Interestingly, a serine proteinase homolog (Sp-SPH) was obtained together with an antimicrobial peptide-antilipopolysaccharide factor (Sp-ALF). We then determined the full-length cDNA sequence of Sp-SPH, which contained 1298bp with an open reading frame of 1107bp encoding 369 amino acid residues. Multiple alignment analysis showed that the deduced amino acid sequences of Sp-SPH shared overall identity (83.8%) with those of SPH-containing proteins from other crab species. Tissue distribution analysis indicated that the Sp-SPH transcripts were present in various tissues including eye stalk, subcuticular epidermis, gill, hemocyte, stomach, thorax ganglion, brain and muscle of S. paramamosain. The Sp-SPH was highly expressed in selected different development stages including embryo (I, II, III and V), zoea (I), megalopa, and juvenile. Importantly, the prophenoloxidase was also present in the embryos, zoea, juvenile and adult crabs, but relatively lower in megalopa compared to those of other stages. Furthermore, the Sp-SPH mRNA expression showed a statistically significant increase (P<0.05) in both hemocyte and subcuticular epidermis at 24h, and in gill at 96h after challenge of V. parahaemolyticus determined by quantitative real-time PCR. Taken together, the live-bacterial-binding activity and the acute-phase response against bacterial infection of Sp-SPH suggested that it might function as an innate immune recognition molecule and play a key role in host defense against microbe invasion in the crab S. paramamosain.
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Affiliation(s)
- Hai-peng Liu
- State Key Laboratory of Marine Environmental Science, College of Oceanography and Environmental Science, Xiamen University, Siming Nanlu No. 422, Xiamen, Fujian, PR China.
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Sumathipala N, Jiang H. Involvement of Manduca sexta peptidoglycan recognition protein-1 in the recognition of bacteria and activation of prophenoloxidase system. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2010; 40:487-95. [PMID: 20416376 PMCID: PMC2931796 DOI: 10.1016/j.ibmb.2010.04.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 04/02/2010] [Accepted: 04/02/2010] [Indexed: 05/20/2023]
Abstract
Although the importance of peptidoglycan recognition proteins (PGRPs) in detecting bacteria and promoting immunity is well recognized in Drosophila melanogaster and other insect species, such a role has not yet been experimentally established for PGRPs in the tobacco hornworm, Manduca sexta. In this study, we purified M. sexta PGRP1 from the baculovirus-insect cell expression system, tested its association with peptidoglycans and intact bacteria, and explored its possible link with the prophenoloxidase activation system in larval hemolymph. Sequence comparison suggested that PGRP1 is not an amidase and lacks residues for interacting with the carboxyl group of meso-diaminopimelic acid-peptidoglycans (DAP-PGs). M. sexta PGRP1 gene was constitutively expressed at a low level in fat body, and the mRNA concentration became much higher after an injection of Escherichia coli. Consistently, the protein concentration in larval plasma increased in a time-dependent manner after the immune challenge. Purified recombinant PGRP1 specifically bound to soluble DAP-PG of E. coli but not to soluble Lys-type PG of Staphylococcus aureus. In addition, this recognition protein completely bound to insoluble PGs from Micrococcus luteus, Bacillus megaterium and Bacillus subtilis, whereas its association with the bacterial cells was low even though their peptidoglycans are exposed on the cell surface. After PGRP1 had been added to plasma of naïve larvae in the absence of microbial elicitor, there was a concentration-dependent increase in prophenoloxidase activation. Phenoloxidase activity, as usual, increased after the plasma was incubated with peptidoglycans or bacterial cells. These increases became more prominent when insoluble M. luteus or B. megaterium PG or soluble E. coli PG and PGRP1 were both present. Statistic analysis suggested a synergistic effect caused by interaction between PGRP1 and these PGs. Taken together, these results indicated that PGRP1 is a member of the M. sexta prophenoloxidase activation system, which recognizes peptidoglycans from certain bacteria and initiates the host defense response. The unexplained difference between the purified PGs and intact bacteria clearly reflects our general lack of understanding of PGRP1-mediated recognition and how it leads to proPO activation.
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Affiliation(s)
- Niranji Sumathipala
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Wang Y, Jiang H. Binding properties of the regulatory domains in Manduca sexta hemolymph proteinase-14, an initiation enzyme of the prophenoloxidase activation system. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2010; 34:316-22. [PMID: 19900472 PMCID: PMC2813979 DOI: 10.1016/j.dci.2009.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 10/06/2009] [Accepted: 11/02/2009] [Indexed: 05/09/2023]
Abstract
Pathogen recognition and rapid initiation of defense responses are essential for the survival of host insects. In Manduca sexta, hemolymph proteinase-14 precursor (proHP14) senses non-self presence and triggers a branched serine proteinase pathway which leads to prophenoloxidase activation and melanin formation around the invading organisms. To understand functions of individual domains in HP14, we have produced a series of HP14 domains and truncation mutants and studied their interactions with microbial polysaccharides and beta-1,3-glucan recognition protein-1 (betaGRP1)-a biosensor for fungal and bacterial infection. These include: the low-density lipoprotein receptor class A repeats 1-5 (LDL(1-5)), Sushi domain, Wonton domain, and proteinase catalytic domain of HP14, as well as proHP14 missing 1-4 LDL repeats (DeltaLDL(1), DeltaLDL(12), DeltaLDL(1-3) and DeltaLDL(1-4)). LDL(1-5), Sushi, and Wonton domains specifically recognized Lys-type PG, whereas the latter two also bound betaGRP1. Wonton in addition bound to lipopolysaccharide (LPS), lipoteichoic acid (LTA), and meso-diaminopimelic acid (DAP)-type peptidoglycan (PG). The four N-terminally truncated proHP14 (DeltaL(x)) further confirmed specific interactions with LPS, LTA, DAP-PG, Lys-PG, laminarin, and betaGRP1. These binding data suggest a broad specificity of proHP14 in pattern recognition. Its role in mediating immune responses is anticipated to be influenced by other plasma factors and surface structures of invading pathogens.
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Affiliation(s)
- Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Zhao P, Zhu KY, Jiang H. Heterologous expression, purification, and biochemical characterization of a greenbug (Schizaphis graminum) acetylcholinesterase encoded by a paralogous gene (ace-1). J Biochem Mol Toxicol 2010; 24:51-9. [DOI: 10.1002/jbt.20311] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Jiang H, Liu S, Zhao P, Pope C. Recombinant expression and biochemical characterization of the catalytic domain of acetylcholinesterase-1 from the African malaria mosquito, Anopheles gambiae. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2009; 39:646-53. [PMID: 19607916 PMCID: PMC2772825 DOI: 10.1016/j.ibmb.2009.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 06/08/2009] [Accepted: 07/07/2009] [Indexed: 05/28/2023]
Abstract
Acetylcholinesterases (AChEs) and their genes from susceptible and resistant insects have been extensively studied to understand the molecular basis of target site insensitivity. Due to the existence of other resistance mechanisms, however, it can be problematic to correlate directly a mutation with the resistant phenotype. An alternative approach involves recombinant expression and characterization of highly purified wild-type and mutant AChEs, which serves as a reliable platform for studying structure-function relationships. We expressed the catalytic domain of Anopheles gambiae AChE1 (r-AgAChE1) using the baculovirus system and purified it 2,500-fold from the conditioned medium to near homogeneity. While K(M)'s of r-AgAChE1 were comparable for ATC, AbetaMTC, PTC, and BTC, V(max)'s were substantially different. The IC(50)'s for eserine, carbaryl, paraoxon, BW284C51, malaoxon, and ethopropazine were 8.3, 72.5, 83.6, 199, 328, and 6.59 x 10(4) nM, respectively. We determined kinetic constants for inhibition of r-AgAChE1 by four of these compounds. The enzyme bound eserine or paraoxon stronger than carbaryl or malaoxon. Because the covalent modification of r-AgAChE1 by eserine occurred faster than that by the other compounds, eserine is more potent than paraoxon, carbaryl, and malaoxon. Furthermore, we found that choline inhibited r-AgAChE1, a phenomenon related to the enzyme activity decrease at high concentrations of acetylcholine.
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Affiliation(s)
- Haobo Jiang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
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Jitvaropas R, Amparyup P, Gross PS, Tassanakajon A. Functional characterization of a masquerade-like serine proteinase homologue from the black tiger shrimp Penaeus monodon. Comp Biochem Physiol B Biochem Mol Biol 2009; 153:236-43. [DOI: 10.1016/j.cbpb.2009.03.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 03/07/2009] [Accepted: 03/08/2009] [Indexed: 01/02/2023]
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Wang Y, Jiang H. A positive feedback mechanism in the Manduca sexta prophenoloxidase activation system. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2008; 38:763-9. [PMID: 18625399 PMCID: PMC3304462 DOI: 10.1016/j.ibmb.2008.04.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 03/29/2008] [Accepted: 04/02/2008] [Indexed: 05/24/2023]
Abstract
In Manduca sexta, pathogen recognition triggers a branched serine proteinase cascade which generates active phenoloxidase (PO) in the presence of a proPO-activating proteinase (PAP) and two noncatalytic serine proteinase homologs (SPHs). PO then catalyzes the production of reactive compounds for microbe killing, wound healing, and melanin formation. In this study, we discovered that a minute amount of PAP1 (a final component of the proteinase pathway) caused a remarkable increase in PO activity in plasma from naïve larvae, which was significantly higher than that from the same amounts of PAP1, proPO and SPHs incubated in vitro. The enhanced proPO activation concurred with the proteolytic activation of HP6, HP8, PAP1, SPH1, SPH2 and PO precursors. PAP1 cleaved proSPH2 to yield bands with mobility identical to SPH2 generated in vivo. PAP1 partially hydrolyzed proHP6 and proHP8 at a bond amino-terminal to the one cut in the PAP1-added plasma. PAP1 did not directly activate proPAP1. These results suggest that a self-reinforcing mechanism is built into the proPO activation system and other plasma proteins are required for cleaving proHP6 and proHP8 at the correct site to strengthen the defense response, perhaps in the early stage of the pathway activation.
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Affiliation(s)
- Yang Wang
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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Lu Z, Beck MH, Wang Y, Jiang H, Strand MR. The viral protein Egf1.0 is a dual activity inhibitor of prophenoloxidase-activating proteinases 1 and 3 from Manduca sexta. J Biol Chem 2008; 283:21325-33. [PMID: 18519564 DOI: 10.1074/jbc.m801593200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Some pathogens are capable of suppressing the melanization response of host insects, but the virulence factors responsible are largely unknown. The insect pathogen Microplitis demolitor bracovirus encodes the Egf family of small serine proteinase inhibitors. One family member, Egf1.0, was recently shown to suppress melanization of hemolymph in Manduca sexta in part by inhibiting the enzymatic activity of prophenoloxidase activating proteinase 3 (PAP3). However, other experiments suggested this viral protein suppresses melanization by more than one mechanism. Here we report that Egf1.0 inhibited the amidolytic activity of PAP1 and dose-dependently blocked processing of pro-PAP1 and pro-PAP3. Consistent with its PAP inhibitory activity, Egf1.0 also prevented processing of pro-phenoloxidase, serine proteinase homolog (SPH) 1, and SPH2. Isolation of Egf1.0-protein complexes from plasma indicated that Egf1.0 binds PAPs through its C-terminal repeat domain. Egf1.0 also potentially interacts with SPH2 and two other proteins, ferritin and gloverin, not previously associated with the phenoloxidase cascade. Overall, our results indicate that Egf1.0 is a dual activity PAP inhibitor that strongly suppresses the insect melanization response.
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Affiliation(s)
- Zhiqiang Lu
- Department of Entomology, University of Georgia, Athens, GA 30602, USA
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