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    DNA secondary structure formation by DNA shuffling of the conserved domains of the Cry protein of Bacillus thuringiensis.
    BMC Biophys 2017 22;10. Epub 2017 May 22.
    Laboratory of Biotechnology and Molecular Biology, MASIRA Institute, School of Health, University of Santander, UDES, Bucaramanga, Colombia.
    Background: The Cry toxins, or δ-endotoxins, are a diverse group of proteins produced by Bacillus thuringiensis. While DNA secondary structures are biologically relevant, it is unknown if such structures are formed in regions encoding conserved domains of Cry toxins under shuffling conditions. We analyzed 5 holotypes that encode Cry toxins and that grouped into 4 clusters according to their phylogenetic closeness. The mean number of DNA secondary structures that formed and the mean Gibbs free energy [Formula: see text] were determined by an in silico analysis using different experimental DNA shuffling scenarios. In terms of spontaneity, shuffling efficiency was directly proportional to the formation of secondary structures but inversely proportional to ∆G.

    Results: The results showed a shared thermodynamic pattern for each cluster and relationships among sequences that are phylogenetically close at the protein level. The regions of the cry11Aa, Ba and Bb genes that encode domain I showed more spontaneity and thus a greater tendency to form secondary structures (<∆G). In the region of domain III; this tendency was lower (>∆G) in the cry11Ba and Bb genes. Proteins that are phylogenetically closer to Cry11Ba and Cry11Bb, such as Cry2Aa and Cry18Aa, maintained the same thermodynamic pattern. More distant proteins, such as Cry1Aa, Cry1Ab, Cry30Aa and Cry30Ca, featured different thermodynamic patterns in their DNA.

    Conclusion: These results suggest the presence of thermodynamic variations associated to the formation of secondary structures and an evolutionary relationship with regions that encode highly conserved domains in Cry proteins. The findings of this study may have a role in the in silico design of cry gene assembly by DNA shuffling techniques.

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    PLoS One 2011 16;6(5):e19952. Epub 2011 May 16.
    Departmento de Microbiologia Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico.
    Background: Bacillus thuringiensis Cry toxins are used worldwide in the control of different insect pests important in agriculture or in human health. The Cry proteins are pore-forming toxins that affect the midgut cell of target insects. It was shown that non-toxic Cry1Ab helix α-4 mutants had a dominant negative (DN) phenotype inhibiting the toxicity of wildtype Cry1Ab when used in equimolar or sub-stoichiometric ratios (1∶1, 0. Read More
    A strategy for shuffling numerous Bacillus thuringiensis crystal protein domains.
    J Econ Entomol 2004 Dec;97(6):1805-13
    AgResearch Ltd., Wallaceville Animal Research Centre, Ward Street, Upper Hutt, New Zealand.
    Bacillus thuringiensis that produce Cry1Ba are toxic to Lucilia cuprina Wiedemann blow fly maggots in vivo, and when applied in quantity to sheep fleece, provide up to 6 wk protection against flystrike in the field. These strains also are toxic to Epiphyas postvittana (Walker) light brown apple moth caterpillars. B. Read More
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    Curr Microbiol 1999 Jul;39(1):14-20
    Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
    We investigated the binding proteins for three Cry toxins, Cry1Aa, Cry1Ac, and the phylogenetically distant Cry9Da, in the midgut cell membrane of the silkworm. In a ligand blot experiment, Cry1Ac and Cry9Da bound to the same 120-kDa aminopeptidase N (APN) as Cry1Aa. A competition experiment with the ligand blot indicated that the three toxins share the same binding site on several proteins. Read More
    [Localization and identification of crystal protein genes in Bacillus thuringiensis strain 4.0718].
    Wei Sheng Wu Xue Bao 2008 Sep;48(9):1250-5
    Key Laboratory of Molecular Microbiology of Hunan Province, College of Life Science, Hunan Normal University, Changsha 410081, China.
    Objective: To localize and identify the insecticidal crystal protein genes (cry genes) in high-toxic Bacillus thuringiensis strain 4.0718.

    Methods: The genomic DNA of B. Read More