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苏云金芽胞杆菌Cry1Ac蛋白的定点突变及结构与功能研究
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摘要
苏云金芽胞杆菌(Bacillus thuringiensis,简称Bt)是世界上应用范围最广的杀虫微生物,其杀虫活性主要来源于芽胞形成过程中产生的杀虫晶体蛋白,研究杀虫晶体蛋白的结构与功能的关系成为当前的一个热点。Cry1Ac蛋白是目前所知的对鳞翅目昆虫毒性最高蛋白分子之一,在农作物和森林害虫防治、蚊虫控制及水生态系统中害虫防治都具有广泛的应用,但其结构与功能的关系尚未完全明确,需要运用定点突变技术进一步阐释。
     本论文运用分子生物学理论和生物信息学技术,发现了Cry1Ac5蛋白结构域Ⅲ中独特的β18-β19 loop,通过定点突变技术研究了Cry1Ac5蛋白结构与功能的关系,同时还获得了杀虫活性或稳定性提高的突变子。主要创新的研究内容如下:
     从高毒力的Bt4.0718菌株中分离克隆了cry1Ac5全长基因,利用穿梭载体pHT315构建了表达载体pHTAc35,电转入无晶体突变株cry~-B中,高效表达了130 kDa的Cry1Ac5蛋白,为研究Cry1Ac5蛋白结构与功能提供了前提条件。
     利用Swiss-Model服务器和Swiss-pdb Viewer软件建立了Cry1Ac5蛋白的三维结构模型,并利用Clustal W和DS ViewerPro软件对比分析了其与其它Cry蛋白之间的差异,发现Cry1Ac5的结构域Ⅲ与其它Cry1蛋白的亲缘关系较远,其结构域Ⅲ上的β18-β19 loop比Cry1Aa、Cry2Aa、Cry3Aa和Cry4Aa蛋白对应的loop长,其组成的残基中色氨酸(W544)、连续的丝氨酸(S547、S548)和loop顶点的天冬酰氨(N546)在Cry蛋白中都是独特的残基分子成分。
     对β18-β19 loop上的7个残基进行丙氨酸扫描突变,所有突变子(N543A、W544A、G545A、N546A、S547A、S548A、I549A)都能产生菱形晶体和表达130 kDa的蛋白。室内生测表明,突变子N546A对棉铃虫和甜菜夜蛾的致死率有明显提高,而W544A的致死率则显著下降;对Cry1Ac5蛋白分子的三维结构分析表明,N546、S548的侧链伸向蛋白分子表面,可能参与蛋白与其受体分子的相互作用,而W544、G545、S547和I549的侧链伸向蛋白分子内侧,可能与维持蛋白的稳定性有关。
     对N546进一步突变,获得了突变子N546G、N546D、N546K和删除突变N546Δ及3个双突变和1个三突变,利用等电点沉淀法和AKTApurifier 100系统纯化了毒素蛋白,生测发现N546A(LC_(50)为1.67μg/mL)对棉铃虫毒力比野生型Cry1Ac(LC_(50)为2.98μg/mL)提高了1.78倍,而N546D、N546K和N546Δ的毒力则降低了80~90%。对野生和突变蛋白进行寡聚体形成能力和胰蛋白酶敏感性分析,发现N546不参与寡聚体的形成和维持蛋白的稳定。利用生物素标记蛋白法进行毒素蛋白与昆虫中肠BBMV的竞争和非竞争结合分析,发现N546A的初始结合能力比野生型增强了2倍;N546D初始结合能力与野生型相当,很容易被野生型Cry1Ac竞争;其它N546突变子与BBMV的初始结合能力则明显下降。因此,N546A突变蛋白毒力的强弱与其同昆虫BBMV的结合力强弱一致。
     进一步对W544突变获得保守的W544F、W544Y和不保守W544C突变子,生测和稳定性分析发现544位残基分子结构有无芳香环不是蛋白功能必须的,但亲水的侧链不利于蛋白的稳定;SDS-PAGE分析发现突变子W544F的原毒素明显的增加了蛋白对紫外线、胰蛋白酶和存贮的稳定性;经原子力显微镜观察,W544F产生的晶体两个顶点间的垂直距离比野生型Cry1Ac长0.6μm;W544F与野生Cry1Ac的杀虫活性相似,但经过紫外照射9 h后,其保留的杀虫活性比野生型高4倍以上,这一结果对解决Cry1Ac毒素蛋白田间应用的问题,具有重要的应用价值。
     本论文首次发现了Cry1Ac5蛋白结构域Ⅲ上的β18-β19 loop结构的特殊性,并第一次报道了结构域Ⅲ中的loop结构在蛋白功能中发挥的作用,为Cry1Ac的结构域Ⅲ在受体分子的识别和结合、维持蛋白的结构稳定等方面的重要性提供了新的生物学证据。
Bacillus thuringiensis(Bt)is the most used insecticidal microorganism that produces one or more insecticidal crystal(Cry)proteins deposited in the form of an intracellular parasporal crystal during sporulation,and it is a current hotpot to study the structure-function relationship of the Cry proteins. Cry1Ac protein,which is one of the widely researched Cry proteins with the strongest insecticidal activities against lepidoptera insects,was extensively used in pest control of agriculture,forestry and water ecology.But the structure-function relationship of Cry1Ac protein has not been well understood and need further discussed and explained with site-directed mutagenesis.
     In this paper,a uniqueβ18-β19 loop in the domainⅢof Cry1Ac5 was reported,and the Structural Significance of this loop in insecticidal activity of Cry1Ac5 was studied by site-directed mutagenesis.The major contents and results are as follows:
     The full-length cry1Ac5 gene was isolated and cloned from Bt 4.0718 strain,and the expression plasmid pHTAc35 was generated by cloning cry1Ac5 gene to shuttle vector pHT315.Acrystalliferous Bacillus thuringiensis cry~-B was transformed with pHTAc35 and well expressed a 130-kDa Cry1Ac5 protoxin,which offered the precondition for our latter research.
     A homology-based Cry1Ac model of Cry1Ac5 was constructed using SWISS-MODEL and Swiss-Pdb Viewer program,and its differences from Cry1Aa,Cry2Aa,Cry3Aa and Cry4Aa structures were analyzed.The Cry1Ac5 domainⅢhas a distant relationship with other Cry1 proteins and its longβ18-β19 loop possesses a unique tryptophan(W)at residue 544 and a unique asparagine(N)at the loop apex(residue 546),as well as two consecutive serines(S)from residue 547 to 548.
     Alanine scanning mutations within the loop were initially generated and all mutants could produce bipyramidal crystals and express 130 kDa protoxins. When tested in toxicity,mutant N546A showed a slight enhanced mortality to Spodoptera exigua and Heliothis armigera,and mutant W544A exhibited a remarkable reduction in mortality to the two insects.After substantial analysis of Cry1Ac5 tertiary-structure,it can be found that both the residues N546 and S548,as well as the N543,are oriented towards the solvent,in the surface of the protein,probably indicating a putative role in interaction to other macromolecules.In contrast,side chain of residues W544,G545,S547 and I549 are in close contact to residues located in the large loop linkingβ21 andβ22,playing a conceivable structural role in local stability.
     Four further single mutants ofN546(N546G,N546D,N546K,N546Δ), three double mutants and a triple mutant were constructed,and toxins were purified by isoelectric precipitation and an AKTA purifier 100 system.When bioassayed against H.armigera using purified toxins,N546A(LC_(50)1.67μg/mL)showed 1.78 times increased toxicity than wide-type Cry1Ac(LC_(50) 2.98μg/mL),and mutant N546D,N546K and N546Δshowed a great loss in toxicity.Toxin oligomerisation and proteolytic susceptibility assays revealed that this residue might not involved in toxin oligomerisation and maintaining the stability of toxin.Brush border membrane vesicles(BBMV)binding assay using biotinylated toxin revealed that the enhanced toxicity of mutant N546A was because of increased binding to BBMV,and reduction in toxicity of other mutants were caused by reduction in initial or inreversible binding to BBMV.
     The W544 was further conservatively substituted with phenylalanine(F) and tyrosine(Y)and nonconservatively replaced by cysteine(C).Bioassay and protein stability analysis indicated that the aromatic ring at this position was not absolutely necessary but the hydrophilic nature of the position had unfavorable influence to protein stability.Comparative analysis by SDS-PAGE showed that the protoxin of W544F was much more stable than the wild-type Cry1Ac,when treated with ultraviolet irradiation,trypsin and preserved at room temperature.The distance between two vertexes of the crystal of W544F was 0.6μm longer than that of the wild-type Cry1Ac under an atomic force microscope.Besides,the mutation W544F had similar insecticidal activity to wild-type Cry1Ac,but when treated with ultraviolet irradiation for 9 hours,it still maintained more than 4 times higher toxicity than the wild-type Cry1Ac,which might contribute to solving the major problem of field applications of Cry1Ac toxin.
     In this paper,the uniqueβ18-β19 loop in domainⅢof Cry1Ac5 toxin and its structural significance in the toxin functions was reported for the first time,which provided new biological evidences for domainⅢof Cry1Ac playing important roles in maintaining the stability of protein structure,and recognizing and binding with specific receptors.
引文
[1]中国科学院微生物研究所.伯杰氏细菌鉴定手册.北京:科学出版社,1984.
    [2]喻子牛.苏云金杆菌.北京:科学出版社,1990.
    [3]Schnepf E,Crickmore N,Van Rie J,et al.Bacillus thuringiensis and its pesticidal crystal proteins.Microbiol Mol Biol Rev,1998,62(3):775-806.
    [4]Hofte H,Whiteley HR.Insecticidal crystal proteins of Bacillus thuringiensis.Microbiol Rev,1989,53(2):242-55.
    [5]Lecadet MM,Frachon E,Dumanoir VC,et al.Updating the H-antigen classification of Bacillus thuringiensis.J Appl Microbiol,1999,86(4):660-72.
    [6]Quesada-Moraga E,Garcia-Tovar E,Valverde-Garcia P,et al.Isolation,geographical diversity and insecticidal activity of Bacillus thuringiensis from soils in Spain.Microbiol Res,2004,159(1):59-71.
    [7]Seleena P,Lee HL,Lecadet MM.A novel insecticidal serotype of Clostridium bifermentans.JAm Mosq Control Assoc,1997,13(4):395-7.
    [8]Seleena P,Lee HL,Lecadet MM.A new serovar of Bacillus thuringiensis possessing 28a28c flagellar antigenic structure:Bacillus thuringiensis serovar jegathesan,selectively toxic against mosquito larvae.JAm Mosq Control Assoc,1995,11(4):471-3.
    [9]Ackermann HW,Azizbekyan RR,Bernier RL,et al.Phage typing of Bacillus subtilis and Bacillus thuringiensis.Res Microbiol,1995,146(8):643-57.
    [10]Murakami T,Hiraoka K,Mikami T,et al.Analysis of common antigen of flagella in Bacillus cereus and Bacillus thuringiensis.FEMS Microbiol Lett,1993,107(2-3):179-83.
    [11]Orduz S,Rojas W,Correa MM,et al.A new serotype of Bacillus thuringiensis from Colombia toxic to mosquito larvae.J Invertebr Pathol,1992,59(1):99-103.
    [12]Kati H,Sezen K,Nalcacioglu R,et al.A highly pathogenic strain of Bacillus thuringiensis serovar kurstaki in lepidopteran pests.J Microbiol,2007,45(6):553-7.
    [13]Sanchis V,Lereclus D.Bacillus thuringiensis:a biotechnology model.J SocBiol,1999,193(6):523-30.
    [14]Wei JZ,Hale K,Carta L,et al.Bacillus thuringiensis crystal proteins that target nematodes.Proc Natl Acad Sci U S A,2003,100(5):2760-5.
    [15]Roh JY,Choi JY,Li MS,et al.Bacillus thuringiensis as a specific,safe,and effective tool for insect pest control.J Microbiol Biotechnol,2007,17(4):547-59.
    [16]Prieto-Samsonov DL,Vazquez-Padron RI,Ayra-Pardo C,et al.Bacillus thuringiensis:from biodiversity to biotechnology.J Ind Microbiol Biotechnol,1997,19(3):202-19.
    [17]Lecadet MM,Chaufaux J,Ribier J,et al.Construction of Novel Bacillus thuringiensis Strains with Different Insecticidal Activities by Transduction and Transformation.Appl Environ Microbiol,1992,58(3):840-849.
    [18]Schnepf HE,Tomczak K,Ortega JP,et al.Specificity-determining regions of a lepidopteran-specific insecticidal protein produced by Bacillus thuringiensis.J Biol Chem,1990,265(34):20923-30.
    [19]Hajaij-Ellouze M,Fedhila S,Lereclus D,et al.The enhancin-like metalloprotease from the Bacillus cereus group is regulated by the pleiotropic transcriptional activator PlcR but is not essential for larvicidal activity.FEMS Microbiol Lett,2006,260(1):9-16.
    [20]Chen YL,Lu W,Chen YH,et al.Cloning,expression and sequence analysis of chiA,chiB in Bacillus thuringiensis subsp.colmeri 15A3. Wei Sheng Wu Xue Bao,2007,47(5):843-8.
    [21]Yu CG,Mullins MA,Warren GW,et al.The Bacillus thuringiensis vegetative insecticidal protein Vip3A lyses midgut epithelium cells of susceptible insects.Appl Environ Microbiol,1997,63(2):532-6.
    [22]Zhu C,Ruan L,Peng D,et al.Vegetative insecticidal protein enhancing the toxicity of Bacillus thuringiensis subsp kurstaki against Spodoptera exigua.Lett Appl Microbiol,2006,42(2):109-14.
    [23]Kalman S,Kiehne KL,Cooper N,et al.Enhanced production of insecticidal proteins in Bacillus thuringiensis strains carrying an additional crystal protein gene in their chromosomes.Appl Environ Microbiol,1995,61(8):3063-8.
    [24]蒲蛰龙.昆虫病理学.广东:广东科学技术出版社,1992.
    [25]Carlton B Z,Gronalez J.Molecular Biology of Microbial Differentiation,American Society for Microbiology.Washington:Washington D.C,1985.
    [26]Kronstad JW,Schnepf HE,Whiteley HR.Diversity of locations for Bacillus thuringiensis crystal protein genes.J Bacteriol,1983,154(1):419-28.
    [27]Sanchis V,Lereclus D,Menou G,et al.Multiplicity of delta-endotoxin genes with different insecticidal specificities in Bacillus thuringiensis aizawai 7.29.Mol Microbiol,1988,2(3):393-404.
    [28]Carlson CR,Kolsto AB.A complete physical map of a Bacillus thuringiensis chromosome.J Bacteriol,1993,175(4):1053-60.
    [29]Daburov KN.Hygienic basis for regulating the use of bacterial insecticides in agriculture and the permissible residues of their producer,Bacillus thuringiensis,in plant products.Gig Sanit,1979(9):27-31.
    [30]Lereclus D,Delecluse,Lecadet M-M.Diversity of Bacillus thuringiensis toxin and genes.Bacillus thuringiensis,An Environmental Biopesticide:Theory and Practice.New York:John Wiley and Sons,1993.
    [31]Gruss A,Ehrlich SD.The family of highly interrelated single-stranded deoxyribonucleic acid plasmids.Microbiol Rev,1989,53(2):231-41.
    [32]Bourgouin C,Delecluse A,Ribier J,et al.A Bacillus thuringiensis subsp.israelensis gene encoding a 125-kilodalton larvicidal polypeptide is associated with inverted repeat sequences.J Bacteriol,1988,170(8):3575-83.
    [33]Kronstad JW,Whiteley HR.Inverted repeat sequences flank a Bacillus thuringiensis crystal protein gene.JBacteriol,1984,160(1):95-102.
    [34]Stately D P,Dingman D W,Bulla L A,et al.Possible origin and function of the parasporal crystals in Bacillus thuringiensis.Biochemical and Biophysical Research Communications,1978,84:581-588.
    [35]Schnepf HE,Wong HC,Whiteley HR.Expression of a cloned Bacillus thuringiensis crystal protein gene in Escherichia coli.J Bacteriol,1987,169(9):4110-8.
    [36]Barton KA,Whiteley HR,Yang NS.Bacillus thuringiensis section sign-Endotoxin Expressed in Transgenic Nicotiana tabacum Provides Resistance to Lepidopteran Insects.Plant Physiol,1987,85(4):1103-1109.
    [37]Crickmore N,Zeigler DR,Feitelson J,et al.Revision of the nomenclature for the Bacillus thuringiensis pesticidal crystal proteins.Microbiol Mol Biol Rev 1998,62(3):807-13.
    [38]王津红,吴卫辉,陈月华.中国苏云金杆菌的分布及 cry 基因多样性.中国病毒学,2000,15(s1):241.
    [39]侯丙凯,党本元,章银梅,等.苏云金芽孢杆菌 cry1Aa10 杀虫晶体蛋白基因的克隆序列分析以及在大肠杆菌中的表达.农业生物技术学报,2000,8(3):289-293.
    [40]Bravo A,Gill SS,Soberon M.Mode of action of Bacillus thuringiensis Cry and Cyt toxins and their potential for insect control.Toxicon,2007,49(4):423-35.
    [41]de Maagd RA,Bravo A,Crickmore N.How Bacillus thuringiensis has evolved specific toxins to colonize the insect world.Trends Genet,2001,17(4):193-9.
    [42]Li JD,Carroll J,Ellar DJ.Crystal structure of insecticidal delta-endotoxin from Bacillus thuringiensis at 2.5 A resolution.Nature,1991,353(6347):815-21.
    [43]Grochulski P,Masson L,Borisova S,et al.Bacillus thuringiensis CrylA(a)insecticidal toxin:crystal structure and channel formation.J MolBiol,1995,254(3):447-64.
    [44]Morse RJ,Yamamoto T,Stroud RM.Structure of Cry2Aa suggests an unexpected receptor binding epitope.Structure,2001,9(5):409-17.
    [45]Galitsky N,Cody V,Wojtczak A,et al.Structure of the insecticidal bacterial delta-endotoxin Cry3Bbl of Bacillus thuringiensis.Acta Crystallogr D Biol Crystallogr,2001,57(Pt 8):1101-9.
    [46]Boonserm P,Davis P,Ellar DJ,et al.Crystal structure of the mosquito-larvicidal toxin Cry4Ba and its biological implications.J Mol Biol,2005,348(2):363-82.
    [47]Boonserm P,Mo M,Angsuthanasombat C,et al.Structure of the functional form of the mosquito larvicidal Cry4Aa toxin from Bacillus thuringiensis at a 2.8-angstrom resolution.J Bacteriol,2006,188(9):3391-401.
    [48]Li J,Derbyshire DJ,Promdonkoy B,et al.Structural implications for the transformation of the Bacillus thuringiensis delta-endotoxins from water-soluble to membrane-inserted forms.Biochem Soc Trans,2001,29(Pt4):571-7.
    [49]Gutierrez P,Alzate O,Orduz S.A theoretical model of the tridimensional structure of Bacillus thuringiensis subsp.medellin Cry 11Bb toxin deduced by homology modelling.Mem Inst Oswaldo Cruz,2001,96(3):357-64.
    [50]Xia LQ,Zhao XM,Ding XZ,et al.The theoretical 3D structure of Bacillus thuringiensis Cry5Ba.JMol Model,2008,14(9):843-8.
    [51]Walters FS,Slatin SL,Kulesza CA,et al.Ion channel activity of N-terminal fragments from CrylA(c)delta-endotoxin.Biochem Biophys Res Commun,1993,196(2):921-6.
    [52]Lee MK,Rajamohan F,Jenkins JL,et al.Role of two arginine residues in domain Ⅱ,loop 2 of CrylAb and Cry 1 Ac Bacillus thuringiensis delta-endotoxin in toxicity and binding to Manduca sexta and Lymantria dispar aminopeptidase N.Mol Microbiol,2000,38(2):289-98.
    [53]Nishimoto T,Yoshisue H,Ihara K,et al.Functional analysis of block 5,one of the highly conserved amino acid sequences in the 130-kDa CrylVA protein produced by Bacillus thuringiensis subsp.israelensis.FEBSLett,1994,348(3):249-54.
    [54]Chen XJ,Lee MK,Dean DH.Site-directed mutations in a highly conserved region of Bacillus thuringiensis delta-endotoxin affect inhibition of short circuit current across Bombyx mori midguts.Proc Natl Acad Sci USA,1993,90(19):9041-5.
    [55]Lee MK,You TH,Gould FL,et al.Identification of residues in domain Ⅲ of Bacillus thuringiensis Cry 1 Ac toxin that affect binding and toxicity.Appl Environ Microbiol,1999,65(10):4513-20.
    [56]Lee MK,Young BA,Dean DH.Domain Ⅲ exchanges of Bacillus thuringiensis CrylA toxins affect binding to different gypsy moth midgut receptors.Biochem Biophys Res Commun,1995,216(1):306-12.
    [57]Gill SS,Cowles EA,Pietrantonio PV.The mode of action of Bacillus thuringiensis endotoxins.Annu Rev Entomol,1992,37:615-36.
    [58]Dean DH,Rajamohan F,Lee MK,et al.Probing the mechanism of action of Bacillus thuringiensis insecticidal proteins by site-directed mutagenesis-a minireview.Gene,1996,179(1):111-7.
    [59]Liu Y,Tabashnik BE.Inheritance of Resistance to the Bacillus thuringiensis Toxin CrylC in the Diamondback Moth.Appl Environ Microbiol,1997,63(6):2218-2223.
    [60]Janmaat AF,Wang P,Kain W,et al.Inheritance of resistance to Bacillus thuringiensis subsp.kurstaki in Trichoplusia ni.Appl Environ Microbiol,2004,70(10):5859-67.
    [61]Kain WC,Zhao JZ,Janmaat AF,et al.Inheritance of resistance to Bacillus thuringiensis Cry 1 Ac toxin in a greenhouse-derived strain of cabbage looper(Lepidoptera:Noctuidae).J Econ Entomol,2004,97(6):2073-8.
    [62]Aronson AI,Han ES,McGaughey W,et al.The solubility of inclusion proteins from Bacillus thuringiensis is dependent upon protoxin composition and is a factor in toxicity to insects.Appl Environ Microbiol,1991,57(4):981-6.
    [63]Bradley D,Harkey MA,Kim MK,et al.The insecticidal CrylB crystal protein of Bacillus thuringiensis ssp.thuringiensis has dual specificity to coleopteran and lepidopteran larvae.J Invertebr Pathol,1995,65(2):162-73.
    [64]Carroll J,Li J,Ellar DJ.Proteolytic processing of a coleopteran-specific delta-endotoxin produced by Bacillus thuringiensis var.tenebrionis.BiochemJ,1989,261(1):99-105.
    [65]Reddy ST,Kumar NS,Venkateswerlu G.Identification and purification of the 69-kDa intracellular protease involved in the proteolytic processing of the crystal delta-endotoxin of Bacillus thuringiensis subsp.tenebrionis.FEMS Microbiol Lett,2000,183(1):63-6.
    [66]Haider MZ,Knowles BH,Ellar DJ.Specificity of Bacillus thuringiensis var.colmeri insecticidal delta-endotoxin is determined by differential proteolytic processing of the protoxin by larval gut proteases.Eur J Biochem,1986,156(3):531-40.
    [67]Haider MZ,Ellar DJ.Functional mapping of an entomocidal delta-endotoxin.Single amino acid changes produced by site-directed mutagenesis influence toxicity and specificity of the protein.J Mol Biol,1989,208(1):183-94.
    [68]Masson L,Mazza A,Brousseau R,et al.Kinetics of Bacillus thuringiensis toxin binding with brush border membrane vesicles from susceptible and resistant larvae of Plutella xylostella.J Biol Chem,1995,270(20):11887-96.
    [69]Rajamohan F,Alzate O,Cotrill JA,et al.Protein engineering of Bacillus thuringiensis delta-endotoxin:mutations at domain Ⅱ of CrylAb enhance receptor affinity and toxicity toward gypsy moth larvae.Proc Natl Acad Sci USA,1996,93(25):14338-43.
    [70]Rajamohan F,Lee MK,Dean DH.Bacillus thuringiensis insecticidal proteins:molecular mode of action.Prog Nucleic Acid Res Mol Biol,1998,60:1-27.
    [71]Mohammed SI,Johnson DE,Aronson AI.Altered binding of the Cry 1 Ac toxin to larval membranes but not to the toxin-binding protein in Plodia interpunctella selected for resistance to different Bacillus thuringiensis isolates.Appl Environ Microbiol,1996,62(11):4168-73.
    [72]Liang Y,Patel SS,Dean DH.Irreversible binding kinetics of Bacillus thuringiensis CryIA delta-endotoxins to gypsy moth brush border membrane vesicles is directly correlated to toxicity.J Biol Chem,1995,270(42):24719-24.
    [73]Carroll J,Wolfersberger MG,Ellar DJ.The Bacillus thuringiensis Cry 1 Ac toxin-induced permeability change in Manduca sexta midgut brush border membrane vesicles proceeds by more than one mechanism.J Cell Sci,1997,110(Pt 24):3099-104.
    [74]Yamamoto T,Powell G K.Bacillus thuringiensis crystal proteins:recent advances in understanding its insecticidal activity.In L.Kim(ed.),Advanced engineered pesticides.New York:Marcel Dekker,Inc,1993.
    [75]Valaitis AP,Lee MK,Rajamohan F,et al.Brush border membrane aminopeptidase-N in the midgut of the gypsy moth serves as the receptor for the CryIA(c)delta-endotoxin of Bacillus thuringiensis.Insect Biochem Mol Biol,1995,25(10):1143-51.
    [76]Knight PJ,Crickmore N,Ellar DJ.The receptor for Bacillus thuringiensis Cry1A(c)delta-endotoxin in the brush border membrane of the lepidopteran Manduca sexta is aminopeptidase N.Mol Microbiol,1994,11(3):429-36.
    [77]Knight PJ,Knowles BH,EUar DJ.Molecular cloning of an insect aminopeptidase N that serves as a receptor for Bacillus thuringiensis CrylA(c)toxin.J Biol Chem,1995,270(30):17765-70.
    [78]Vadlamudi RK,Ji TH,Bulla LA Jr.A specific binding protein from Manduca sexta for the insecticidal toxin of Bacillus thuringiensis subsp.berliner.J Biol Chem,1993,268(17):12334-40.
    [79]Martinez-Ramirez AC,Gonzalez-Nebauer S,Escriche B,et al.Ligand blot identification of a Manduca sexta midgut binding protein specific to three Bacillus thuringiensis CryIA-type ICPs.Biochem Biophys Res Commun,1994,201(2):782-7.
    [80]Griffitts JS,Haslam SM,Yang T,et al.Glycolipids as receptors for Bacillus thuringiensis crystal toxin.Science,2005,307(57ll):922-5.
    [81]Knowles BH,Knight PJ,Ellar DJ.N-acetyl galactosamine is part of the receptor in insect gut epithelia that recognizes an insecticidal protein from Bacillus thuringiensis.Proc Biol Sci,1991,245(1312):31-5.
    [82]Cooper MA,Carroll J,Travis ER,et al.Bacillus thuringiensis Cry1Ac toxin interaction with Manduca sexta aminopeptidase N in a model membrane environment.Biochem J,1998,333(Pt 3):677-83.
    [83]Knowles B H,Ellar D J.Colloid-osmotic lysis is a general feature of the mechanism of action of Bacillus thuringiensis δ-endotoxins with different insect specificity.Biochimica et biophysica acta,1987,924:509-518.
    [84]Hodgman TC,Ellar DJ.Models for the structure and function of the Bacillus thuringiensis delta-endotoxins determined by compilational analysis.DNA Seq,1990,1(2):97-106.
    [85]Gazit E,La Rocca P,Sansom MS,et al.The structure and organization within the membrane of the helices composing the pore-forming domain of Bacillus thuringiensis delta-endotoxin are consistent with an“umbrella-like”structure of the pore.Proc Natl Acad Sci USA,1998,95(21):12289-94.
    [86]Masson L,Tabashnik BE,Liu YB,et al.Helix 4 of the Bacillus thuringiensis Cry1Aa toxin lines the lumen of the ion channel.J Biol Chem,1999,274(45):31996-2000.
    [87]Schwartz JL,Juteau M,Grochulski P,et al.Restriction of intramolecular movements within the CrylAa toxin molecule of Bacillus thuringiensis through disulfide bond engineering.FEBS Lett,1997,410(2-3):397-402.
    [88]Gazit E,Bach D,Kerr ID,et al.The alpha-5 segment of Bacillus thuringiensis delta-endotoxin:in vitro activity,ion channel formation and molecular modelling.Biochem J,1994,304(Pt 3):895-902.
    [89]Rajamohan F,Hussain SR,Cotrill JA,et al.Mutations at domain Ⅱ,loop 3,of Bacillus thuringiensis CrylAa and CryIAb delta-endotoxins suggest loop 3 is involved in initial binding to lepidopteran midguts.J Biol Chem,1996,271(41):25220-6.
    [90]Rajamohan F,Cotrill JA,Gould F,et al.Role of domain Ⅱ,loop 2 residues of Bacillus thuringiensis CrylAb delta-endotoxin in reversible and irreversible binding to Manduca sexta and Heliothis virescens.J Biol Chem,1996,271(5):2390-6.
    [91]de Maagd RA,Bakker PL,Masson L,et al.Domain Ⅲ of the Bacillus thuringiensis delta-endotoxin Cry1Ac is involved in binding to Manduca sexta brush border membranes and to its purified aminopeptidase N.Mol Microbiol,1999,31(2):463-71.
    [92]Masson L,Tabashnik BE,Mazza A,et al.Mutagenic analysis of a conserved region of domain Ⅲ in the Cry1Ac toxin of Bacillus thuringiensis.Appl Environ Microbiol,2002,68(1):194-200.
    [93]Allured VS,Collier R J,Carroll SF,et al.Structure of exotoxin A of Pseudomonas aeruginosa at 3.0-Angstrom resolution.Proc Natl Acad Sci USA,1986,83(5):1320-4.
    [94]Choe S,Bennett MJ,Fujii G,et al.The crystal structure of diphtheria toxin.Nature,1992,357(6375):216-22.
    [95]Ojcius DM,Young JD.Cytolytic pore-forming proteins and peptides:is there a common structural motif.Trends Biochem Sci,1991,16(6):225-9.
    [96]Yool AJ.Block of the inactivating potassium channel by clofilium and hydroxylamine depends on the sequence of the pore region.Mol Pharmacol,1994,46(5):970-6.
    [97]MacKinnon R,Yellen G.Mutations affecting TEA blockade and ion permeation in voltage-activated K+ channels.Science,1990,250(4978):276-9.
    [98]MacKinnon R,Miller C.Mutant potassium channels with altered binding of charybdotoxin,a pore-blocking peptide inhibitor.Science,1989,245(4924):1382-5.
    [99]吴乃虎.基因工程原理(第二版).北京:科学出版,2006.
    [100]Sambrook,Joseph/Russell,David W.Molecular Cloning(the third edition).New York:Cold Spring Harbor Laboratory Press,2001.
    [101]李立家 肖庚富.基因工程.北京版.科学出版社,2005.
    [102]张浩,毛秉智.定点突变技术研究进展.免疫学杂志,2000,16(4):108-110.
    [103]Vallone B,Vecchini P,Cavalli V,et al.Site-directed mutagenesis in hemoglobin.Effect of some mutations at protein interfaces.FEBS Lett,1993,324(2):117-22.
    [104]Kono M,Miyazaki G,Nakamura H,et al.Site-directed mutagenesis in hemoglobin:attempts to control the oxygen affinity with cooperativity preserved.Protein Eng,1998,11(3):199-204.
    [105]Nachimuthu S.Protein engineering of 5-endotoxins of Bacillus thuringiensis.Electronic Journal of Biotechnology,2004,7(5):178-188.
    [106]Vachon V,Prefontaine G,Rang C,et al.Helix 4 mutants of the Bacillus thuringiensis insecticidal toxin Cry1Aa display altered pore-formingabilities.Appl Environ Microbiol,2004,70(10):6123-30.
    [107]Wu D,Aronson Al.Localized mutagenesis defines regions of the Bacillus thuringiensis delta-endotoxin involved in toxicity and specificity.J Biol Chem,1992,267(4):2311-7.
    [108]Nunez V.M,Sanchez J,Lina L,et al.Structural and functional studies of K-helix 5 region from Bacillus thuringiensis CrylAb δ-endotoxin.Biochimica et Biophysica Acta,2001,1546:122-131.
    [109]Chandra A,Ghosh P,Mandaokar AD,et al.Amino acid substitution in alpha-helix 7 of Cry1Ac delta-endotoxin of Bacillus thuringiensis leads to enhanced toxicity to Helicoverpa armigera Hubner.FEBS Lett,1999,458(2):175-9.
    [110]Alcantara EP,Alzate O,Lee MK,et al.Role of alpha-helix seven of Bacillus thuringiensis CrylAb delta-endotoxin in membrane insertion,structural stability,and ion channel activity.Biochemistry,2001,40(8):2540-7.
    [111]Wu SJ,Dean DH.Functional significance of loops in the receptor binding domain of Bacillus thuringiensis CryIIIA delta-endotoxin.J Mol Biol,1996,255(4):628-40.
    [112]Lee MK,Jenkins JL,You TH,et al.Mutations at the arginine residues in alpha8 loop of Bacillus thuringiensis delta-endotoxin Cry1Ac affect toxicity and binding to Manduca sexta and Lymantria dispar aminopeptidase N.FEBS Lett,2001,497(2-3):108-12.
    [113]Coux F,Vachon V,Rang C,et al.Role of interdomain salt bridges in the pore-forming ability of the Bacillus thuringiensis toxins Cry1Aa and Cry1Ac.J Biol Chem,2001,276(38):35546-51.
    [114]Rajamohan F,Alcantara E,Lee MK,et al.Single amino acid changes in domain Ⅱ of Bacillus thuringiensis CrylAb delta-endotoxin affect irreversible binding to Manduca sexta midgut membrane vesicles.J Bacteriol,1995,177(9):2276-82.
    [115]Padilla C,Pardo-Lopez L,de la Riva G,et al.Role of tryptophan residues in toxicity of Cry1Ab toxin from Bacillus thuringiensis.Appl Environ Microbiol,2006,72(1):901-7.
    [116]Abdul-Rauf M,Ellar DJ.Mutations of loop 2 and loop 3 residues in domain Ⅱ of Bacillus thuringiensis Cry1C delta-endotoxin affect insecticidal specificity and initial binding to Spodoptera littoralis and Aedes aegypti midgut membranes.Curr Microbiol,1999,39(2):94-8.
    [117]Ayra-Pardo C,Davis P,Ellar DJ.The mutation R(423)S in the Bacillus thuringiensis hybrid toxin CryAAC slightly increases toxicity for Mamestra brassicae L.J Invertebr Pathol,2007,95(1):41-7.
    [118]de Maagd RA,Kwa MS,van der Klei H,et al.Domain Ⅲ substitution in Bacillus thuringiensis delta-endotoxin CryIA(b)results in superior toxicity for Spodoptera exigua and altered membrane protein recognition.Appl Environ Microbiol,1996,62(5):1537-43.
    [119]Wolfersberger MG,Chen XJ,Dean DH.Site-directed mutations in the third domain of Bacillus thuringiensis delta-endotoxin CryIAa affect its ability to increase the permeability of Bombyx mori midgut brush border membrane vesicles.Appl Environ Microbiol,1996,62(1):279-82.
    [120]Bah A,van Frankenhuyzen K,Brousseau R,et al.The Bacillus thuringiensis Cry1Aa toxin:effects of trypsin and chymotrypsin site mutations on toxicity and stability.J Invertebr Pathol,2004,85(2):120-7.
    [121]Schwartz JL,Potvin L,Chen XJ,et al.Single-site mutations in the conserved alternating-arginine region affect ionic channels formed by CrylAa,a Bacillus thuringiensis toxin.Appl Environ Microbiol,1997,63(10):3978-84.
    [122]Angsuthanasombat C,Crickmore N,Ellar DJ.Effects on toxicity of eliminating a cleavage site in a predicted interhelical loop in Bacillus thuringiensis CryIVB delta-endotoxin.FEMS Microbiol Lett,1993,111(2-3):255-61.
    [123]Lee MK,You TH,Curtiss A,et al.Involvement of two amino acid residues in the loop region of Bacillus thuringiensis Cry1Ab toxin in toxicity and binding to Lymantria dispar.Biochem Biophys Res Commun,1996,229(1):139-46.
    [124]Wu SJ,Koller CN,Miller DL,et al.Enhanced toxicity of Bacillus thuringiensis Cry3A delta-endotoxin in coleopterans by mutagenesis in a receptor binding loop.FEBS Lett,2000,473(2):227-32.
    [125]Smedley DP,Ellar DJ.Mutagenesis of three surface-exposed loops of a Bacillus thuringiensis insecticidal toxin reveals residues important for toxicity,receptor recognition and possibly membrane insertion.Microbiology,1996,142(Pt 7):1617-24.
    [126]Abdullah MA,Alzate O,Mohammad M,et al.Introduction of Culex toxicity into Bacillus thuringiensis Cry4Ba by protein engineering.Appl Environ Microbiol,2003,69(9):5343-53.
    [127]Kumar AS,Aronson AI.Analysis of mutations in the pore-forming region essential for insecticidal activity of a Bacillus thuringiensis delta-endotoxin.JBacteriol,1999,181(19):6103-7.
    [128]Karlova R,Weemen-Hendriks M,Naimov S,et al.Bacillus thuringiensis delta-endotoxin CrylAc domain Ⅲ enhances activity against Heliothis virescens in some,but not all Cry1-Cry1Ac hybrids.J Invertebr Pathol,2005,88(2):169-72.
    [129]Sarvjeet K.Molecular approaches towards development of novel Bacillus thuringiensis biopesticides.World Journal of Microbiology &Biotechnology,2000,16:781-793.
    [130]丁学知,夏立秋.苏云金杆菌高毒力菌株4.0718的快速选育.中国国生物防治,2001(04):163-166.
    [131]Arantes O,Lereclus D.Construction of cloning vectors for Bacillus thuringiensis.Gene,1991,108(1):115-9.
    [132]Arvidson H,Dunn PE,Stmad S,et al.Specificity of Bacillus thuringiensis for lepidopteran larvae:factors involved in vivo and in the structure of a purified protoxin.Mol Microb iol,1989,3(11):1533-43.
    [133]Song F,Zhang J,Gu A,et al.Identification of crylI-type genes from Bacillus thuringiensis strains and characterization of a novel cry1I-type gene.Appl Environ Microbiol,2003,69(9):5207-11.
    [134]Xia L,Sun Y,Ding X,et al.Identification of cry-type genes on 20-kb DNA associated with Cry1 crystal proteins from Bacillus thuringiensis.Curr Microbiol,2005,51(1):53-8.
    [135]Crickmore N,Zeigler DR,Schnepf E,et al.“Bacillus thuringiensis toxin nomenclature”.http://www.lifesci.sussex.ac.uk/Home/Neil_Crickmore/Bt/,2007:Cited 1 Sep 2008.
    [136]Guex N,Peitsch MC.SWISS-MODEL and the Swiss-PdbViewer:an environment for comparative protein modeling.Electrophoresis,1997,18(15):2714-23.
    [137]Schwede T,Kopp J,Guex N,et al.SWISS-MODEL:An automated protein homology-modeling server.Nucleic Acids Res, 2003,31(13):3381-5.
    [138]Arnold K,Bordoli L,Kopp J,et al.The SWISS-MODEL workspace:a web-based environment for protein structure homology modelling.Bioinformaties,2006,22(2):195-201.
    [139]Combet C,Blanchet C,Geourjon C,et al.NPS@:network protein sequence analysis.Trends Biochem Sci,2000,25(3):147-50.
    [140]Liu XS,Dean DH.Redesigning Bacillus thuringiensis Cry1Aa toxin into a mosquito toxin.Protein Eng Des Sel,2006,19(3):107-11.
    [141]Burton SL,Ellar D J,Li J,et al.N-acetylgalactosamine on the putative insect receptor aminopeptidase N is recognised by a site on the domain Ⅲ lectin-like fold of a Bacillus thuringiensis insecticidal toxin.J Mol Biol,1999,287(5):1011-22.
    [142]Jenkins JL,Lee MK,Valaitis AP,et al.Bivalent sequential binding model of a Bacillus thuringiensis toxin to gypsy moth aminopeptidase N receptor.JBiol Chem,2000,275(19):14423-31.
    [143]屈伸,刘志国.分子生物学实验技术.北京:化学工业出版社,2008.
    [144]曾晓慧,张宏宇,喻子牛,等.苏云金芽孢杆菌对甜菜夜蛾幼虫毒力的生物测定方法.中国生物防治,1998,14(4):172-5.
    [145]Sun Y,Wei W,Ding X,et al.Detection of chromosomally located and plasmid-borne genes on 20 kb DNA fragments in parasporal crystals from Bacillus thuringiensis.Arch Microbiol,2007,188(4):327-32.
    [146]Hemsley A,Arnheim N,Toney MD,et al.A simple method for site-directed mutagenesis using the polymerase chain reaction.Nucleic Acids Res,1989,17(16):6545-51.
    [147]Nelson M,McClelland M.Use of DNA methyltransferase/endonuclease enzyme combinations for megabase mapping of chromosomes.Methods Enzymol,1992,216:279-303.
    [148]Nelson M,McClelland M.Purification and assay of type Ⅱ DNA methylases.Methods Enzymol,1987,155:32-41.
    [149]Boonserm P,Angsuthanasombat C,Lescar J.Crystallization and preliminary crystallographic study of the functional form of the Bacillus thuringiensis mosquito-larvicidal Cry4Aa mutant toxin.Acta Crystallogr D Biol Crystallogr,2004,60(Pt 7):1315-8.
    [150]Tapaneeyakorn S,Pornwiroon W,Katzenmeier G,et al.Structural requirements of the unique disulphide bond and the proline-rich motif within the alpha4-alpha5 loop for larvicidal activity of the Bacillus thuringiensis Cry4Aa delta-endotoxin.Biochem Biophys Res Commun,2005,330(2):519-25.
    [151]Almond BD,Dean DH.Structural stability of Bacillus thuringiensis delta-endotoxin homolog-scanning mutants determined by susceptibility to proteases.Appl Environ Microbiol,1993,59(8):2442-8.
    [152]Aronson AI.Flexibility in the protoxin composition of Bacillus thuringiensis.FEMS Microbiol Lett,1994,117(1):21-7.
    [153]Ralet MC,Crepeau MJ,Lefebvre J,et al.Reduced Number of Homogalacturonan Domains in Pectins of an Arabidopsis Mutant Enhances the Flexibility of the Polymer.Biomacromolecules,2008.
    [154]Likitvivatanavong S,Katzenmeier G,Angsuthanasombat C.Asn in alpha5 is essential for oligomerisation and toxicity of the Bacillus thuringiensis Cry4Ba toxin.Arch Biochem Biophys,2006,445(1):46-55.
    [155]Zhou FX,Merianos HJ,Brunger AT,et al.Polar residues drive association of polyleucine transmembrane helices.Proc Natl Acad Sci USA,2001,98(5):2250-5.
    [156]Bradford MM.A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.Anal Biochem,1976,72:248-54.
    [157]Seale JW.The role of a conserved histidine-tyrosine interhelical interaction in the ion channel domain of delta-endotoxins from Bacillus thuringiensis.Proteins,2006,63(2):385-90.
    [158]Wolfersberger MG.Preparation and partial characterization of amino acid transporting brush border membrane vesicles from the larval midgut of the gypsy moth(Lymantria dispar).Arch Insect Biochem Physiol,1993,24(3):139-47.
    [159]Wolfersberger MG,Luethy P,Maurer A,et al.Preparation and partial characterization of amino acid transporting brush border membrane vesicles from the larval midgut of the cabbage butterfly(Pieris brussicae).Comp Biochem Physiol 86A,1987,301(2):301-8.
    [160]Biber J,Stieger B,Haase W,et al.A high yield preparation for rat kidney brush border membranes.Different behaviour of lysosomal markers.Biochim Biophys Acta,1981,647(2):169-76.
    [161]Guereca L,Bravo A.The oligomeric state of Bacillus thuringiensis Cry toxins in solution.Biochim Biophys Acta,1999,1429(2):342-50.
    [162]Pardo-Lopez L,Gomez I,Rausell C,et al Structural changes of the Cry1Ac oligomeric pre-pore from Bacillus thuringiensis induced by N-acetylgalactosamine facilitates toxin membrane insertion.Biochemistry,2006,45(34):10329-36.
    [163]Roh JY,Lee IH,Li MS,et al.Expression of a recombinant Cry1Ac crystal protein fused with a green fluorescent protein in Bacillus thuringiensis subsp.kurstaki Cry-B.J Microbiol,2004,42(4):340-5.
    [164]Xu X,Wu Y.Disruption of HaBtR alters binding of Bacillus thuringiensis delta-endotoxin Cry1Ac to midgut BBMVs of Helicoverpa armigera.J Invertebr Pathol,2008,97(1):27-32.
    [165]Banks DJ,Jurat-Fuentes JL,Dean DH,et al.Bacillus thuringiensis Cry1Ac and Cry1Fa delta-endotoxin binding to a novel 110 kDa aminopeptidase in Heliothis virescens is not N-acetylgalactosamine mediated.Insect Biochem MolBiol,2001,31(9):909-18.
    [166]Avilla C,Vargas-Osuna E,Gonzalez-Cabrera J,et al.Toxicity of several delta-endotoxins of Bacillus thuringiensis against Helicoverpa armigera(Lepidoptera:Noctuidae)from Spain.J Invertebr Pathol,2005,90(1):51-4.
    [167]Liao C,Heckel DG,Akhwst R.Toxicity of Bacillus thuringiensis insecticidal proteins for Helicoverpa armigera and Helicoverpa punctigera(Lepidoptera:Noctuidae),major pests of cotton.J Invertebr Pathol,2002,80(1):55-63.
    [168]Jimenez-Juarez N,Munoz-Garay C,Gomez I,et al.Bacillus thuringiensis Cry1Ab mutants affecting oligomer formation are non-toxic to Manduca sexta larvae.J Biol Chem,2007,282(29):21222-9.
    [169]Gomez I,Sanchez J,Miranda R,et al.Cadherin-like receptor binding facilitates proteolytic cleavage of helix alpha-1 in domain I and oligomer pre-pore formation of Bacillus thuringiensis Cry1Ab toxin.FEBS Lett,2002,513(2-3):242-6.
    [170]Rausell C,Munoz-Garay C,Miranda-CassoLuengo R,et al.Tryptophan spectroscopy studies and black lipid bilayer analysis indicate that the oligomeric structure of Cry1Ab toxin from Bacillus thuringiensis is the membrane-insertion intermediate.Biochemistry,2004,43(1):166-74.
    [171]Obeta JA.Effect of inactivation by sunlight on the larvicidal activities of mosquitocidal Bacillus thuringiensis H-14 isolates from Nigerian soils.JCommun Dis,1996,28(2):94-100.
    [172]Pusztai M,Fast P,Gringorten L,et al.The mechanism of sunlight-mediated inactivation of Bacillus thuringiensis crystals.Biochem J,1991,273(Pt 1):43-7.
    [173]Pozsgay,M,P.Fast,H.Kaplan,et al.The effect of sunlight on the protein crystals from Bacillus thuringiensis var.kurstaki HD1 and NRD12:a Raman spectroscopic study.J.Invertebr.Pathol,2001,50:246-253.

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