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Fortea E, Lemieux V, Potvin L, Chikwana V, Griffin S, Hey T, McCaskill D, Narva K, Tan SY, Xu X, Vachon V, Schwartz JL. Cry6Aa1, a Bacillus thuringiensis nematocidal and insecticidal toxin, forms pores in planar lipid bilayers at extremely low concentrations and without the need of proteolytic processing. J Biol Chem 2017. [PMID: 28623231 DOI: 10.1074/jbc.m116.765941] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cry6Aa1 is a Bacillus thuringiensis (Bt) toxin active against nematodes and corn rootworm insects. Its 3D molecular structure, which has been recently elucidated, is unique among those known for other Bt toxins. Typical three-domain Bt toxins permeabilize receptor-free planar lipid bilayers (PLBs) by forming pores at doses in the 1-50 μg/ml range. Solubilization and proteolytic activation are necessary steps for PLB permeabilization. In contrast to other Bt toxins, Cry6Aa1 formed pores in receptor-free bilayers at doses as low as 200 pg/ml in a wide range of pH (5.5-9.5) and without the need of protease treatment. When Cry6Aa1 was preincubated with Western corn rootworm (WCRW) midgut juice or trypsin, 100 fg/ml of the toxin was sufficient to form pores in PLBs. The overall biophysical properties of the pores were similar for all three forms of the toxin (native, midgut juice- and trypsin-treated), with conductances ranging from 28 to 689 pS, except for their ionic selectivity, which was slightly cationic for the native and midgut juice-treated Cry6Aa1, whereas dual selectivity (to cations or anions) was observed for the pores formed by the trypsin-treated toxin. Enrichment of PLBs with WCRW midgut brush-border membrane material resulted in a 2000-fold reduction of the amount of native Cry6Aa1 required to form pores and affected the biophysical properties of both the native and trypsin-treated forms of the toxin. These results indicate that, although Cry6Aa1 forms pores, the molecular determinants of its mode of action are significantly different from those reported for other Bt toxins.
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Affiliation(s)
- Eva Fortea
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Vincent Lemieux
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada.,the Département de biologie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Léna Potvin
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | | | | | - Timothy Hey
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | | | - Kenneth Narva
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Sek Yee Tan
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Xiaoping Xu
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Vincent Vachon
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Jean-Louis Schwartz
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada, .,the Centre SÈVE de recherche en sciences du végétal, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1 Canada
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Dojnov B, Pavlović R, Božić N, Margetić A, Nenadović V, Ivanović J, Vujčić Z. Expression and distribution of cellulase, amylase and peptidase isoforms along the midgut of Morimus funereus L. (Coleoptera: Cerambycidae) larvae is dependent on nutrient substrate composition. Comp Biochem Physiol B Biochem Mol Biol 2013; 164:259-67. [PMID: 23402787 DOI: 10.1016/j.cbpb.2013.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 02/01/2013] [Accepted: 02/04/2013] [Indexed: 11/18/2022]
Abstract
The influence of diet composition--two substrates, wheat bran and sawdust--on isoform expression of digestive enzymes (cellulase, amylase and peptidase) in the midgut of Morimus funereus larvae was examined. Their impact on larval development was demonstrated by measuring the increase of larval weight during development and by analysis of digestive enzymes zymographic profiles, where the expression of cellulase isoforms from M. funereus larvae midgut has been examined for the first time in this study. Larvae reared on wheat bran had higher body weight between day 60 and day 100 than larvae reared on sawdust; however, both groups achieved similar body weight after day 110. Wheat bran as substrate induced different cellulase and amylase isoforms. Oak sawdust in substrate acted as inducer of peptidases. The highest cellulase activity and the greatest isoform variability were detected in the midgut extracts of larvae reared on wheat bran. From our results it can be assumed that M. funereus endocellulase, amylase and peptidase are secreted in the anterior midgut, and their concentration gradually decreases towards the hindgut.
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Affiliation(s)
- Biljana Dojnov
- Department of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Studentski trg 12-16, Belgrade, Serbia.
| | - Ratko Pavlović
- Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade, Serbia
| | - Nataša Božić
- Department of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Studentski trg 12-16, Belgrade, Serbia
| | - Aleksandra Margetić
- Department of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Studentski trg 12-16, Belgrade, Serbia
| | - Vera Nenadović
- Department of Insect Physiology and Biochemistry, Institute for Biological Research Siniša Stanković, University of Belgrade, Despota Stefana 142, Belgrade, Serbia
| | - Jelisaveta Ivanović
- Department of Insect Physiology and Biochemistry, Institute for Biological Research Siniša Stanković, University of Belgrade, Despota Stefana 142, Belgrade, Serbia
| | - Zoran Vujčić
- Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade, Serbia
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Loncar N, Vujcić Z, Bozić N, Ivanović J, Nenadović V. Purification and properties of trypsin-like enzyme from the midgut of Morimus funereus (coleoptera, cerambycidae) Larvae. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2010; 74:232-246. [PMID: 20549815 DOI: 10.1002/arch.20371] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Trypsin-like enzyme (TLE) from the anterior midgut of Morimus funereus larvae was purified by anion exchange chromatography and gel filtration chromatography and characterized. Specific TLE activity was increased 322-fold by purification of the crude midgut extract. The purified enzyme had a pH optimum of 9.0 (optimum pH range 8.5-9.5) and temperature optimum of 45 degrees C with the K(M) ratio of 0.065 mM for benzoyl-arginine-p-nitroanilide (BApNA). Among a number of inhibitors tested, the most efficient was benzamidine (K(I) value of 0.012 mM, Ic(50) value of 0.204 mM) while inhibition of TLE activity by SBTI, TLCK, and PMSF was partial. Almost all divalent cations tested enhanced the enzyme activity, amongst them Co2+ and Mn2+ stimulated TLE activity for 2.5 times. The purified TLE (after gel-filtration on Superose 12 column) had a molecular mass of 37.5 kDa with an isoelectric point over 9.3. Sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed one band of 38 kDa, suggesting that the enzyme is a monomer.
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Affiliation(s)
- Nikola Loncar
- Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Belgrade, Serbia
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Comparison of α-amylase isoforms from the midgut of Cerambyx cerdo L. (Coleoptera: Cerambycidae) larvae developed in the wild and on an artificial diet. ARCH BIOL SCI 2010. [DOI: 10.2298/abs1003575d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
?-Amylase isoforms of Cerambyx cerdo larvae from the wild (ML and SL) and reared in the laboratory (ADL) were compared. Three amylase isoforms were presented in the SL and ML extracts while two isoforms were presented in the ADL according to zymogram after isoelectric focusing (IEF). All C. cerdo amylase isoforms were acidic proteins (pI < 3.5). Seven amylase isoforms (ACC 1-7) from the midgut of C. cerdo larvae were found in the ML midgut extract, six in the SL extract, and four in the ADL extract according to native PAGE zymogram. The ADL amylase had the highest activity. All crude midgut extracts of C. cerdo larvae were fractionated on a Superose 12 HR column. The molecular mass of the ACC was estimated to be 34 kDa. .
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