绿盲蝽多聚半乳糖醛酸酶基因的克隆及生物信息学分析

Cloning and Bioinformatics Analysis of Polygalacturonase Gene of Apolygus lucorum(Meyre-Dür)

从绿盲蝽(Apolygus lucorum)成虫中克隆得到1个多聚半乳糖醛酸酶(Polygalacturonase,PG)基因ALPG(GenBank登录号JQ288100.1),其碱基序列为1 050 bp,编码350个氨基酸。获得的该碱基序列与美国豆荚草盲蝽(Lygus hesperus)PG具有很高的同源性,碱基序列一致性为93%。该基因编码蛋白AL-PG有氨基端疏水信号肽序列(MKFTIYALGLLVAVASA)。预测的成熟肽相对分子质量为35.9 kD,等电点为8.89。AL-PG二级结构由大量的β-折叠、β-转角和无规则卷曲组成,而α-螺旋的数量非常少。AL-PG三级结构是右手平行的β螺旋结构,包含4组β折叠,PB1,PB2a,PB2b和PB3。催化氨基酸残基Asp153,Asp173和Asp174在底物结合裂缝的底部,底物结合裂缝入口的最小距离为8.4。

A polygalacturonase gene AL-PG was cloned from the adults of the Apolygus lucorum （GenBank accession number： JQ288100. 1） ,which contained a 1 050 bp nucleotide sequence encoding 350 amino acids. The obtained sequence had relatively high homology with the sequence of Lygus hesperus PG by sharing 93% sequence identity. AL-PG protein encoded by this gene had a hydrophobic N-terminal signal sequence（MKFTIYALGLLVAVASA） .The calculated molecular mass of the mature protein was 35.9 kD with an estimated pI of 8.89. The secondary structure of AL-PG consisted of many β-sheets, β-turns and random coils, however, there was a small amount of α-helices. The tertiary structure of AL-PG had a right-handed parallel β-helical structure, consisting of four β-sheets, PB1, PB2a, PB2b and PB3. The catalytic amino acid residues, Asp153, Asp173 and Asp174, were at the bottom of substrate binding cleft. The smallest distance at the entry of the substrate binding cleft was 8.4A