少孢节丛孢菌XJ-A1几丁质酶基因的克隆及生物信息学分析

Cloning and Bioinformatics Analysis of the Chitinase Gene from Arthrobotrys oligospora XJ-A1

为研究捕食线虫性真菌几丁质酶的功能,在国内首次对少孢节丛孢菌XJ-A1几丁质酶AO-801和AO-483基因进行扩增、克隆及测序,并对其编码蛋白信号肽、疏水性与亲水性、高级结构、功能域进行预测和分析。结果显示,2个不同蛋白均具有典型的几丁质酶催化区保守序列SXGGW和DGXDXDWE,属于糖苷水解酶18家族几丁质酶,无信号肽序列,表明这2个蛋白为非分泌型蛋白,二级结构以无规则卷曲、α-螺旋和β-折叠为蛋白的主要结构元件,三级结构中有(α/β)8的圆桶形结构。系统发育分析表明,几丁质酶AO-801和AO-483与昆虫病原真菌几丁质酶的亲缘关系更为接近,说明它们所产生的几丁质酶在侵染宿主的过程中发挥着类似的功能,并且不同来源真菌几丁质酶根据分子质量的差异形成3个不同的进化分枝。

In order to study the function of chitinase of Nematode-trapping fungi,the chitinase gene AO-801 and AO-483 were amplified,cloned and sequenced from Arthrobotrys oligospora XJ-A1,and the signal peptide,hydrophobicity and hydrophilicity,secondary structure,tertiary structure and functional domains of the encoded proteins were predicted and analyzed.The results showed that two different proteins have two prevalent conserved catalytic domains with the sequence of SXGGW and DGXDXDWE,belonging to the family 18 glycoside hydrolase.They have no signal peptide sequence,which indicates that both proteins is not a secretory protein.Random coils,alpha-helix and beta-sheet are the major structural elements in secondary structure of chitinase gene AO-801 and AO-483,and（α/β）8rounded buckets in tertiary structure.Phylogenetic analysis showed that the phylogenetic relationship of chitinase AO-801 and AO-483 is more close to the insect pathogenic fungi,they produce chitinase which plays a similar function in the infected host.Different sources of fungal chitinase formed three different evolutionary branches according to molecular size.