繁缕核糖体失活蛋白基因克隆及序列分析

采用同源克隆结合RACE法,克隆了繁缕核糖体失活蛋白的全长cDNA,命名为q3(GenBank accession GQ870262)。序列分析结果表明,q3的开放阅读框(ORF)长780 bp,编码259个氨基酸。序列G+C含量为41.5%,与大部分Ⅰ型RIP基因相近。q3编码的蛋白质命名为Q3,理论分子量为28.16 kD,pI为9.44,均与Ⅰ型核糖体失活蛋白相近;包含由23个氨基酸组成的信号肽。功能结构域分析发现,该蛋白含有3个蛋白激酶磷酸化位点、4个络氨酸蛋白激酶磷酸化位点和7个N-肉豆蔻酰化位点。三级结构预测发现,有35.52%的氨基酸残基参与了α螺旋,24.32%的氨基酸残基组成延伸链,40.15%的氨基酸残基随机缠绕其中。基于繁缕及其近缘种核糖体失活蛋白的氨基酸序列构建的系统发育树显示,其结构与经典分类结果基本一致。

Cloning and Sequence Analysis of Ribosome Inactivating Protein Gene from Stellaria media

Combined the method of homologous cloning with rapid amplification of cDNA ends (RACE),the cDNA full length encoding ribosome-inactivating protein (RIP)which named q3 (GenBank accession No.GQ870262) from Stellaria media was obtained.The length of open reading fragment (ORF) was 780 bp,encoding 259 amino acids.The G+C content of q3 was 41.5%,which was close to many genes encoding RIP I.The protein encoded by q3 was named Q3.The putative molecular weight of Q3 was 28.16 kD and pI was 9.44,which also were near to type Ⅰ RIP.Furthermore,the protein contained signal peptide composed by 23 amino acids.Three protein kinase C phosphorylation sites,4 casein kinase II phosphorylation sites and 7 N-myristoylation sites were found in the amino acids sequence by prosite scanning.Tertiary structure predicted that 35.52% amino acids were α helix,24.32% were extending strand and 40.15% were random coil.Based on amino acids sequences in S.media and its related species,the phylogeny trees were constructed and the framework of the tree answered for morphologic taxonomy.