桃小食心虫CsasCSP14的基因克隆及分子对接

Cloning and molecular docking of the Carposina sasakii chemosensory protein gene,CsasCSP14

【目的】本研究旨在获得桃小食心虫Carposina sasakii Matsumura CsasCSP14基因序列,分析其在雌雄不同组织中的表达差异,并与寄主挥发物进行分子对接,为该基因的功能研究提供参考。【方法】以桃小食心虫全组织cDNA为模板,通过PCR技术扩增克隆获得CsasCSP14 cDNA序列全长;利用生信分析软件分析其编码蛋白的理化性质和结构特征;通过荧光定量PCR技术分析CsasCSP14在桃小食心虫雌雄成虫不同组织(触角、头、胸、腹、足和翅)中的表达情况;使用Modeller(version 9.19)构建CsasCSP14蛋白的三维结构模型;运用Autodock 4.2将CsasCSP14与32种苹果挥发物和2种性信息素分子进行分子对接。【结果】克隆获得了桃小食心虫化学感受蛋白基因CsasCSP14的cDNA序列,其开放阅读框(Open reading frame,ORF)长度为369 bp,编码122个氨基酸,预测其蛋白分子量为14.13 ku,理论等电点为5.20,有17个氨基酸残基组成的信号肽序列,且18-122位氨基酸之间存在昆虫化学感受蛋白家族保守结构域;含有4个保守的半胱氨酸位点。CsasCSP14具有6个α螺旋;氨基酸同源比对结果显示,CsasCSP14与玉米螟Pyrausta nubilalis OfurCSP5的氨基酸序列一致性最高,达到79.01%。荧光定量PCR结果显示,CsasCSP14在雌雄成虫的触角、头、胸、腹、足和翅中均有表达,但是其表达丰度有差异,在雌雄成虫触角中的表达量最高。通过Modeller软件搜索CsasCSP14三维结构的模板,得到与沙漠蝗Schistocerca gregaria CSPsg4序列相似性为65.7%。因此以CSPsg4为模板成功构建CsasCSP14三维结构。分子对接结果表明CsasCSP14与2-己烯醛、桃醛、醋酸丁酯、庚醛、异戊醛和法尼烯气味分子结合能比较低,并且Leu-22、Phe-29、Phe-42和Ile-464个疏水性氨基酸残基在结合过程中发挥了关键作用。【结论】本研究为进一步了解桃小食心虫CsasCSP14基因功能和利用化学生态的方法防控该虫提供了前期理论基础。

[Objectives]To clone the cDNA sequence of the Carposina sasakii CSP14 gene,CsasCSP14,determine its expression profiles in different tissues of both sexes,and its molecular docking with host volatiles,and thereby lay a foundation for the future study of the physiological function of this gene.[Methods]The full-length cDNA sequence of CsasCSP14 was cloned from body tissues of C.sasakii by PCR.The expression levels of CsasCSP14 mRNA in different tissues(antennae,head,thorax,abdomen,legs and wings)were detected by real-time PCR.Modeller software(version-9.19)was used to build a three-dimensional model of CsasCSP14 and Autodock 4.2 was then used to dock this model to 32 apple plant volatiles and 2 sex pheromones.[Results]The open reading frame(ORF)of the full-length cDNA sequence of CsasCSP14 obtained using real-time PCR was 369 bp long,encoding a protein of 122 aa with an estimated molecular weight 14.13 ku and a pI of 5.20.The encoded protein has a signal peptide,no transmembrane structure,a CSP superfamily domain between residues 18-122 and contains four conserved cysteins and 6α-helixes.The results of amino acid sequence alignment indicate that CsasCSP14 is homologous to OfurCSP13 with 86%amino acid sequence identify.Furthermore,the results of real-time PCR show that CsasCSP14 transcripts are differentially expressed in the antennae,head,thorax,abdomen,legs and wings of male and female adults.The highest expression of CsasCSP14 was in the antennae of adult males and females.Modeller was used to compare the sequence of CsasCSP14 with those of previously characterized proteins in the Protein Data Bank(PDB).CsasCSP14 shares 65.03%similarity with S.gregaria CSPsg4;the 3D structure of CSPsg4 was used as the template for the 3D structure of CsasCSP14.[Conclusion]The results of molecular docking simulation indicate that 2-Hexenal,Undecanolactone,Butyl-acetate,Heptanal,3-Methylbutanal and Farnesene have relatively low binding energies with CsasCSP14.However,the hydrophobic amino acid resides Leu-22,Phe-29,Phe-42 and Ile-46,interact with all CsasCSP14 ligands.These results provide a theoretical basis for further research on the binding of CsasCSP14 to host plant volatiles,and thereby facilitate the development of new methods of controlling C.sasakii.