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Giglio ML, Ituarte S, Milesi V, Dreon MS, Brola TR, Caramelo J, Ip JCH, Maté S, Qiu JW, Otero LH, Heras H. Exaptation of two ancient immune proteins into a new dimeric pore-forming toxin in snails. J Struct Biol 2020; 211:107531. [PMID: 32446810 DOI: 10.1016/j.jsb.2020.107531] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 05/01/2020] [Accepted: 05/14/2020] [Indexed: 11/24/2022]
Abstract
The Membrane Attack Complex-Perforin (MACPF) family is ubiquitously found in all kingdoms. They have diverse cellular roles, however MACPFs with pore-forming toxic function in venoms and poisons are very rare in animals. Here we present the structure of PmPV2, a MACPF toxin from the poisonous apple snail eggs, that can affect the digestive and nervous systems of potential predators. We report the three-dimensional structure of PmPV2, at 17.2 Å resolution determined by negative-stain electron microscopy and its solution structure by small angle X-ray scattering (SAXS). We found that PV2s differ from nearly all MACPFs in two respects: it is a dimer in solution and protomers combine two immune proteins into an AB toxin. The MACPF chain is linked by a single disulfide bond to a tachylectin chain, and two heterodimers are arranged head-to-tail by non-covalent forces in the native protein. MACPF domain is fused with a putative new Ct-accessory domain exclusive to invertebrates. The tachylectin is a six-bladed β-propeller, similar to animal tectonins. We experimentally validated the predicted functions of both subunits and demonstrated for the first time that PV2s are true pore-forming toxins. The tachylectin "B" delivery subunit would bind to target membranes, and then the MACPF "A" toxic subunit would disrupt lipid bilayers forming large pores altering the plasma membrane conductance. These results indicate that PV2s toxicity evolved by linking two immune proteins where their combined preexisting functions gave rise to a new toxic entity with a novel role in defense against predation. This structure is an unparalleled example of protein exaptation.
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Affiliation(s)
- M L Giglio
- Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner", INIBIOLP, CONICET CCT La Plata - Universidad Nacional de La Plata (UNLP), Facultad de Ciencias Médicas,1900 La Plata, Argentina
| | - S Ituarte
- Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner", INIBIOLP, CONICET CCT La Plata - Universidad Nacional de La Plata (UNLP), Facultad de Ciencias Médicas,1900 La Plata, Argentina
| | - V Milesi
- Instituto de Estudios Inmunológicos y Fisiopatológicos, IIFP CONICET CCT La Plata - UNLP, Facultad de Ciencias Exactas, 1900 La Plata, Argentina
| | - M S Dreon
- Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner", INIBIOLP, CONICET CCT La Plata - Universidad Nacional de La Plata (UNLP), Facultad de Ciencias Médicas,1900 La Plata, Argentina
| | - T R Brola
- Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner", INIBIOLP, CONICET CCT La Plata - Universidad Nacional de La Plata (UNLP), Facultad de Ciencias Médicas,1900 La Plata, Argentina
| | - J Caramelo
- Instituto de Investigaciones Bioquímicas de Buenos Aires, IIBBA, CONICET - Fundación Instituto Leloir, Av Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina
| | - J C H Ip
- Department of Biology, Hong Kong Baptist University, 224 Waterloo Road, Hong Kong, China
| | - S Maté
- Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner", INIBIOLP, CONICET CCT La Plata - Universidad Nacional de La Plata (UNLP), Facultad de Ciencias Médicas,1900 La Plata, Argentina
| | - J W Qiu
- Department of Biology, Hong Kong Baptist University, 224 Waterloo Road, Hong Kong, China
| | - L H Otero
- Instituto de Investigaciones Bioquímicas de Buenos Aires, IIBBA, CONICET - Fundación Instituto Leloir, Av Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina; Plataforma Argentina de Biología Estructural y Metabolómica PLABEM, Av. Patricias Argentinas 435, C1405BWE Buenos Aires, Argentina.
| | - H Heras
- Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner", INIBIOLP, CONICET CCT La Plata - Universidad Nacional de La Plata (UNLP), Facultad de Ciencias Médicas,1900 La Plata, Argentina; Cátedra de Química Biologica, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata (UNLP), 1900 La Plata, Argentina.
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Ituarte S, Brola TR, Dreon MS, Sun J, Qiu JW, Heras H. Non-digestible proteins and protease inhibitors: implications for defense of the colored eggs of the freshwater apple snailPomacea canaliculata. CAN J ZOOL 2019. [DOI: 10.1139/cjz-2018-0210] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Apple snails (Pomacea Perry, 1810) are successful invaders that cause ecological perturbations, economic losses, and medical issues. A peculiar trait of this snail is a high biological potential, related to the absence of predators of their eggs. Eggs show protease inhibitor (PI) activity, originally ascribed to PcOvo perivitellin in the apple snail Pomacea canaliculata (Lamarck, 1822) but absent in PmPV1, the orthologoue of PcOvo, in eggs of the apple snail Pomacea maculata Perry, 1810. As egg fluid diminishes rat growth rate, an antidigestive effect, similar to plant defenses against herbivory, was hypothesized. However, PI activity has not been characterized in apple snail eggs. Here we identify and partially characterize P. canaliculata egg PI and improve our knowledge of the quaternary structure and evolution of PcOvo. Through N-terminal, transcriptomic or proteomic sequencing, and biochemical validation, we identified a Kunitz-type and a Kazal-type inhibitor that, though at low concentration in the egg, exhibit strong PI activity against trypsin, chymotrypsin, elastase, and subtilisin. Additionally, we report three new subunits for the non-digestible storage protein PcOvo. They are likely products of ancient gene duplication, as their sequences exhibit moderate similarity (30%). To our knowledge, this is the first report of Kazal-type inhibition among invertebrate eggs. Inhibiting varied proteases, PI seems an efficient adaptive trait that limits predator’s capacity to digest egg nutrients.
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Affiliation(s)
- Santiago Ituarte
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata – CONICET, La Plata, Argentina
| | - Tabata Romina Brola
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata – CONICET, La Plata, Argentina
| | - Marcos Sebastián Dreon
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata – CONICET, La Plata, Argentina
- Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina
| | - Jin Sun
- Division of life science, Hong Kong University of Science and Technology, Hong Kong, People’s Republic of China
| | - Jian-Wen Qiu
- Department of Biology, Hong Kong Baptist University, Hong Kong, People’s Republic of China
| | - Horacio Heras
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata – CONICET, La Plata, Argentina
- Department of Biology, Hong Kong Baptist University, Hong Kong, People’s Republic of China
- Facultad de Ciencias Naturales y Museo, UNLP, La Plata, Argentina
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Ituarte S, Brola TR, Fernández PE, Mu H, Qiu JW, Heras H, Dreon MS. A lectin of a non-invasive apple snail as an egg defense against predation alters the rat gut morphophysiology. PLoS One 2018; 13:e0198361. [PMID: 29856808 PMCID: PMC5983499 DOI: 10.1371/journal.pone.0198361] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 05/17/2018] [Indexed: 01/07/2023] Open
Abstract
The eggs of the freshwater Pomacea apple snails develop above the water level, exposed to varied physical and biological stressors. Their high hatching success seems to be linked to their proteins or perivitellins, which surround the developing embryo providing nutrients, sunscreens and varied defenses. The defensive mechanism has been unveiled in P. canaliculata and P. maculata eggs, where their major perivitellins are pigmented, non-digestible and provide a warning coloration while another perivitellin acts as a toxin. In P. scalaris, a species sympatric to the former, the defense strategy seems different, since no toxin was found and the major perivitellin, PsSC, while also colored and non-digestible, is a carbohydrate-binding protein. In this study we examine the structure and function of PsSC by sequencing its subunits, characterizing its carbohydrate binding profile and evaluating its effect on gut cells. Whereas cDNA sequencing and database search showed no lectin domain, glycan array carbohydrate binding profile revealed a strong specificity for glycosphingolipids and ABO group antigens. Moreover, PsSC agglutinated bacteria in a dose-dependent manner. Inspired on the defensive properties of seed lectins we evaluated the effects of PsSC on intestinal cells both in vitro (Caco-2 and IEC-6 cells) and in the gastrointestinal tract of rats. PsSC binds to Caco-2 cell membranes without reducing its viability, while a PsSC-containing diet temporarily induces large epithelium alterations and an increased absorptive surface. Based on these results, we propose that PsSC is involved in embryo defenses by altering the gut morphophysiology of potential predators, a convergent role to plant defensive lectins.
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Affiliation(s)
- Santiago Ituarte
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata (UNLP)–CONICET, La Plata, Argentina
| | - Tabata Romina Brola
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata (UNLP)–CONICET, La Plata, Argentina
| | - Patricia Elena Fernández
- Instituto de Patología B. Epstein, Cátedra de Patología General Veterinaria, Facultad Ciencias Veterinarias, UNLP, La Plata, Argentina
| | - Huawei Mu
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Jian-Wen Qiu
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Horacio Heras
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata (UNLP)–CONICET, La Plata, Argentina
- Cátedra de Química Biológica, Facultad de Ciencias Naturales y Museo, UNLP, La Plata, Argentina
| | - Marcos Sebastián Dreon
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata (UNLP)–CONICET, La Plata, Argentina
- Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, UNLP, La Plata, Argentina
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